Category: Load Balancing NetScaler 12

VMware Horizon Load Balancing – NetScaler / Citrix ADC

Last Modified: Jul 25, 2024 @ 12:06 pm

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Use this procedure to load balance VMware Unified Access Gateway.

Change Log

Overview

To simplify this post, this post is focused on Unified Access Gateway, which is the replacement for Horizon Security Servers.

For load balancing of other Horizon components:

  • Internal Horizon Connection Servers – This is standard load balancing on SSL_BRIDGE protocol, port 443, and Source IP persistence. See the CLI commands for a sample configuration.
    • If you enabled the Secure Gateways (PCoIP, Blast) on the Connection Servers, then load balance the Connection Servers using the same procedure as load balancing UAGs.

UAG appliances vs Horizon Security Servers

There are two VMware-provided remote access solutions for Horizon View:

Unified Access Gateway appliances are preferred over Horizon Security Servers for the following reasons:

  • No need to pair with internal Connection Servers, which simplifies the configuration.
  • Linux appliance instead of Windows server.
  • Authentication can be offloaded to the Unified Access Gateway. This includes: Smart Cards, RSA, and RADIUS.
  • Blast Extreme Adaptive Transport (BEAT) in Horizon 7.1 and newer only works with Unified Access Gateway 2.9 and newer. Security Server and older Access Points don’t work.
    • VMware Blog Post Deep Dive into VMware Horizon Blast Extreme Adaptive Transport – Blast Extreme Adaptive Transport is enabled by default in VMware Horizon View 7.1 and Horizon Client 4.4. If the clients are connecting from outside the demilitarized zone (DMZ), you would also need to have VMware Unified Access Gateway (not Security Server) to take full advantage of the new transport. The adaptive transport will automatically sense the network for UDP availability and will fallback to legacy Blast TCP if UDP is not available.

Here is a typical Unified Access Gateway architecture:

  • Two Internal Connection Servers – these need to be load balanced on an internal VIP on TCP 443. Internal users connect to the internal VIP.
    • Instructions for load balancing the internal Connection Servers are not detailed in this post. Instead, see the CLI Commands.
  • Two DMZ Unified Access Gateway (Access Point) appliances – these need to be load balanced on a DMZ VIP on several ports. External users connect to the DMZ VIP.
    • Unified Access Gateway appliances connect to the internal Load Balancing VIP for the internal Connection Servers using HTTPS protocol
    • Unified Access Gateway appliances connect directly to Horizon Agents using Blast or PCoIP protocol.

During UAG configuration, you specify the address of the internal Connection Servers. The address you enter should be a DNS name that resolves to an internal load balancing VIP for the Connection Servers.

If you have split DNS, you can use the same DNS name for both external UAG access, and for internal Connection Server load balancing. Externally, configure the DNS name to resolve to the UAG Load Balancing VIP. Internally, configure the DNS name to resolve to the internal VIP that load balances the Connection Servers.

For Cloud Pod Architecture, configure separate VIPs in each datacenter. Then configure NetScaler Citrix ADC GSLB to resolve a single DNS name to multiple VIPs.

Protocols/Ports

To support Blast Extreme, PCoIP, and HTML Blast connectivity, the following ports must be load balanced to the UAGs:

  • TCP 443
  • UDP 443
  • TCP 4172
  • UDP 4172
  • TCP 8443
  • UDP 8443

The initial connection to UAG is always TCP 443 (HTTPS). If a user is load balanced on port 443 to a particular UAG, then the connection on UDP 4172 must go the same UAG. Normally load balancing persistence only applies to a single port number, so whatever UAG was selected for port 443, won’t be considered for the 4172 connection. But in NetScaler Citrix ADC, you can configure a Persistency Group to use a single persistency across multiple load balancing Virtual Servers with different port numbers. In F5, you configure Match Across Services, as detailed by Aresh Sarkari at Persistence Profile – F5 LTM Load Balancing for VMware Unified Access Gateway Appliance.

This topic primarily focuses on NetScaler Citrix ADC GUI configuration. Alternatively, you can skip directly to the CLI commands.

Load Balancing Monitors

Users connect to Unified Access Gateway appliances on multiple ports: TCP 443, UDP 443, TCP 8443, UDP 8443, TCP 4172, and UDP 4172. Create Load Balancing Monitors for each port number. Since UDP can’t be easily monitored, use TCP monitors as substitutes for UDP. That means you only need four monitors:

  • TCP 443 – HTTPS
    • HEAD /favicon.ico or GET /favicon.ico. This string can detect if UAG is in Quiesce mode, or if Connection Server is disabled in Horizon Console. See VMware 56636 for supported monitoring strings.
  • TCP 4172
  • TCP 8443

The procedure for configuring monitors changed in NetScaler 12.0 build 56 and newer.

SSL (443) Monitor for Connection Server Health

  1. On the left, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name it Horizon-SSL or similar.
  4. In the Type field, click where it says Click to select.
  5. In the Monitor Types list, click the circle next to HTTP.
  6. Scroll up and click the blue Select button.
  7. To reduce UAG CPU, VMware recommends setting the Interval to 30 seconds.
  8. In the HTTP Request field, enter GET /favicon.ico. See VMware 56636 for supported health monitoring requests.
  9. Check the box next to Secure.
  10. Scroll down and click Advanced Parameters to expand it.
  11. In the Advanced Parameters section, in the Destination Port field, enter 443.
  12. Scroll down to the TROFS Code field and enter 503. When UAG is in Quiesce mode, TROFS will cause the service to transition to out of service allowing existing connections instead of directly going down and killing existing sessions. (h/t Henry Heres)
  13. Scroll down, and click Create.

PCoIP (4172) Monitor

  1. On the left, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name it Horizon-PCoIP or similar.
  4. For the Type field, click where it says Click to select and select TCP from the Monitor Types list.
  5. Scroll down to Advanced Parameters, click Advanced Parameters to expand it, and then enter 4172 in the Destination Port field. This forces the monitor to connect to port 4172 even if the monitor is bound to a service group that is configured for a different port number.
  6. Scroll down, and click Create.

Blast (8443) Monitor

  1. On the left, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name it Horizon-Blast or similar.
  4. For the Type field, click where it says Click to select and select TCP from the Monitor Types list.
  5. Scroll down to Advanced Parameters, click Advanced Parameters to expand it, and then enter 8443 in the Destination Port field. This forces the monitor to connect to port 8443 even if the monitor is bound to a service group that is configured for a different port number.
  6. Scroll down, and click Create.

UAG DDoS

NetScaler Citrix ADC Monitors might trigger UAG’s DDoS protection. To stop this: (source = UAG breaks after a few days. They break 100% of the time. at VMware Discussions)

  1. Point your browser to the UAG appliance’s admin interface using https, port 9443 and path /admin.
  2. Login to the admin interface.
  3. On the right, under Configure Manually, click Select.
  4. In the Advanced Settings section, click the gear icon for System Configuration.
  5. Scroll down.
  6. Change Request Timeout to 0.
  7. Change Body Receive Timeout to 0.
  8. Click Save.

Load Balancing Servers

Create Load Balancing Server Objects for the DMZ Unified Access Gateway appliances.

  1. On the left, expand Traffic Management, expand Load Balancing, and click Servers.
  2. On the right, click Add.
  3. Enter a descriptive server name, usually it matches the actual appliance name.
  4. Enter the IP address of a Unified Access Gateway appliance.
  5. Enter comments to describe the server. Click Create.
  6. Continue adding Unified Access Gateway appliances.

Load Balancing Service Groups

Overview

Since there are six protocol/ports to UAG, there will be six service groups – one for each protocol/port:

  • TCP 443 – SSL_BRIDGE
  • UDP 443
  • UDP 4172
  • TCP 4172
  • TCP 8443 – SSL_BRIDGE
  • UDP 8443

Users will initially connect to TCP port 443, and then must be redirected to one of the other ports on the same UAG appliance that was initially used for the TCP 443 connection. If TCP 443 is up, but UDP 4172 is down on the same appliance, then you probably TCP 443 to go down too. To facilitate this, bind all three port number monitors to the TCP 443 service. If any of the bound monitors goes down, then TCP 443 is also taken down.

  • Only the TCP 443 service group needs to monitor all port numbers.
  • Other port number service groups only need to monitor that specific port number. For example, the TCP 8443 Service Group should monitor port TCP 8443.
  • Since UDP is difficult to monitor, the UDP Service Groups will monitor the equivalent TCP port. For example, the UDP 4172 Service Group will monitor TCP 4172. This isn’t the best option, but it’s better than ping.

TCP 443 Load Balancing Service Group

  1. On the left, expand Traffic Management, expand Load Balancing, and click Service Groups.
  2. On the right, click Add.
  3. Give the Service Group a descriptive name (e.g. svcgrp-Horizon-SSL).
  4. Change the Protocol to SSL_BRIDGE.
  5. Click OK to close the Basic Settings section.
  6. On the left, in the Service Group Members section, click where it says No Service Group Member.

    1. Change the selection to Server Based.
    2. In the Select Server field, click where it says Click to select.
    3. Select the Unified Access Gateway appliances you created earlier, and then at the top of the page click the blue Select button.
    4. In the Port field, enter 443, and click Create.
  7. Click OK to close the Service Group Members section.
  8. On the right, in the Advanced Settings column, click Monitors to move it to the left.
  9. On the left, at the bottom of the page, in the Monitors section, click where it says No Service Group to Monitor Binding.

    1. In the Select Monitor field, click where it says Click to select.
    2. Click the circle next to the Horizon-SSL monitor, and then at the top of the page click the blue Select button.
    3. Click Bind.
  10. For load balancing UAGs, this Service Group should monitor all port numbers so that if any of the port numbers are down then the entire server should no longer receive connections. If load balancing internal Connection Servers, then you don’t need to bind any more monitors since the PCoIP Gateway and Blast Gateway are usually disabled. To bind more monitors, on the left, click where it says 1 Service Group to Monitor Binding.

    1. Click Add Binding.
    2. In the Select Monitor field, click where it says Click to select.
    3. Click the circle next to the Horizon-PCoIP monitor, and then at the top of the page click the blue Select button.
    4. Then click Bind.
    5. Repeat these steps to bind the Horizon-Blast monitor. Unfortunately you can only bind one monitor at a time.
      • If any of these monitors goes down, then the UAG is taken offline.
    6. Click Close.
  11. To verify the monitors, on the left, higher up the page in the Service Group Members section, click the line that says # Service Group Members.

    1. Right-click one of the members, and click Monitor Details.
    2. The Last Response should indicate Success. If you bound multiple monitors to the Service, then the member will only be UP if all monitors succeed.

      • UAG has a Quiesce mode, which tells the load balancer to stop sending it connections. You can enable Quiesce mode in the UAG’s System Configuration menu.
      • Connection Servers can be disabled.
      • If Quiesce mode is enabled on the UAG, or if the Connection Server is disabled, then the member of the service group will show Going Out of Service. You can see this by right-clicking on the Server Group and clicking Manage Members.

    3. Click Close when done.
  12. Then click Done to finish creating the Service Group.

Other Ports Load Balancing Service Groups

Here are general instructions for the other Horizon UAG load balancing service groups.

  1. On the left, go to Traffic Management > Load Balancing > Service Groups.
  2. On the right, click Add.
  3. Name it svcgrp-Horizon-UDP443 or similar.
  4. Change the Protocol to UDP. Click OK to close the Basic Settings section.
  5. On the left, click where it says No Service Group Member.

    1. Change the selection to Server Based, and then click Click to select.
    2. Select your multiple Unified Access Gateway appliances, and then at the top of the page click the blue Select button.
    3. Enter 443 as the Port. Click Create.
  6. Click OK to close the Service Group Members section.
  7. On the right, in the Advanced Settings column, click Monitors to move it to the left.

    1. On the left, in the Monitors section, click where it says No Service Group to Monitor Binding.
    2. For the Select Monitor field, click where it says Click to select.
    3. Select the Horizon-SSL monitor, click Select, and then click Bind. Since we don’t have a UDP monitor, we’re binding the TCP monitor instead.
  8. Click Done to finish creating the Service Group for UDP 443.
  9. Add another Service Group for PCoIP on TCP 4172.
    1. Name = svcgrp-Horizon-PCoIPTCP or similar.
    2. Protocol = TCP
    3. Members = multiple Unified Access Gateway appliances.
    4. Port = 4172.
    5. Monitors = Horizon-PCoIP. You can add the other monitors if desired.
  10. Add another Service Group for PCoIP on UDP 4172.
    1. Name = svcgrp-Horizon-PCoIPUDP or similar.
    2. Protocol = UDP
    3. Members = multiple Unified Access Gateway appliances
    4. Port = 4172.
    5. Monitors = Horizon-PCoIP. You can add the other monitors if desired.
  11. Add another Service Group for SSL_BRIDGE 8443.
    1. Name = svcgrp-Horizon-TCP8443 or similar.
    2. Protocol = SSL_BRIDGE
    3. Members = multiple Unified Access Gateway appliances
    4. Port = 8443.
    5. Monitors = Horizon-Blast. You can add the other monitors if desired.
  12. Add another Service Group for UDP 8443 (Blast Extreme in Horizon 7).
    1. Name = svcgrp-Horizon-UDP8443 or similar.
    2. Protocol = UDP
    3. Members = multiple Unified Access Gateway appliances
    4. Port = 8443.
    5. Monitors = Horizon-Blast. You can add the other monitors if desired.
  13. The six service groups should look something like this:

Load Balancing Virtual Servers

Unified Access Gateway appliances listen on multiple ports so you will need separate load balancers for each port number. Here is a summary of their Virtual Servers, all listening on the same Virtual IP address:

  • Virtual Server on SSL_BRIDGE 443 – bind the SSL_BRIDGE 443 service group.
  • Virtual Server on UDP 443 (Horizon 7) – bind the UDP 443 service group.
  • Virtual Server on UDP 4172 – bind the PCoIP UDP service group.
  • Virtual Server on TCP 4172 – bind the PCoIP TCP service group.
  • Virtual Server on SSL_BRIDGE 8443 – bind the SSL_BRIDGE 8443 service group.
  • Virtual Server on UDP 8443 (Horizon 7) – bind the UDP 8443 service group.

Do the following to create the Virtual Servers:

  1. On the left, under Traffic Management > Load Balancing, click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section:
    1. Name it lbvip-Horizon-SSL or similar.
    2. Change the Protocol to SSL_BRIDGE.
    3. Specify a new VIP. This one VIP will be used for all of the Virtual Servers.
    4. Enter 443 as the Port.
  4. Click OK to close the Basic Settings section.
  5. On the left, in the Services and Service Groups section, click where it says No Load Balancing Virtual Server ServiceGroup Binding.

    1. Click where it says Click to select.
    2. Click the circle next to the Horizon-SSL Service Group, and then at the top of the page click the blue Select button.
    3. Click Bind.
  6. Click Continue to close the Services and Service Groups section.
  7. Then click Done to finish creating the Load Balancing Virtual Server. Persistence will be configured later.
  8. Create another Load Balancing Virtual Server for UDP 443. You can right-click the existing Load Balancing Virtual Server and click Add to copy some settings.

    1. Name = lbvip-Horizon-UDP443
    2. Same VIP as the TCP 443 Load Balancer.
    3. Protocol = UDP, Port = 443
    4. Service Group Binding = the UDP 443 Service Group

  9. Create another Load Balancing Virtual Server for PCoIP UDP 4172:
    1. Name = lbvip-Horizon-PCoIPUDP
    2. Same VIP as the 443 Load Balancer.
    3. Protocol = UDP, Port = 4172
    4. Service Group Binding = the PCoIP UDP Service Group.

  10. Create another Load Balancing Virtual Server for PCoIP TCP 4172:
    1. Name = lbvip-Horizon-PCoIPTCP
    2. Same VIP as the 443 Load Balancer.
    3. Protocol = TCP, Port = 4172
    4. Service Group Binding = the PCoIP TCP Service Group

  11. Create another Load Balancing Virtual Server for SSL_BRIDGE 8443:
    1. Name = lbvip-Horizon-8443SSL
    2. Same VIP as the 443 Load Balancer.
    3. Protocol = SSL_BRIDGE, Port = 8443
    4. Service Group Binding = the TCP 8443 SSL_BRIDGE Service Group

  12. Create another Load Balancing Virtual Server for UDP 8443:
    1. Name = lbvip-Horizon-8443UDP
    2. Same VIP as the 443 Load Balancer.
    3. Protocol = UDP, Port = 8443
    4. Service Group Binding = the UDP 8443 Service Group

  13. This gives you six Load Balancing Virtual Servers on the same VIP, but different protocols and port numbers.

Persistency Group

Users will first connect to SSL_BRIDGE 443 and be load balanced. Subsequent connections to the other port numbers must go to the same load balanced appliance. Create a Persistency Group to facilitate this.

  1. On the left, under Traffic Management, expand Load Balancing, and click Persistency Groups.
  2. On the right, click Add.
  3. Give the Persistency Group a name (e.g. Horizon).
  4. Change the Persistence drop-down to SOURCEIP.
  5. Enter a Time-out that is equal to, or greater than the timeout in Horizon View Administrator, which defaults to 10 hours (600 minutes).
  6. In the Virtual Server Name section, click Add.
  7. Move all six Horizon Load Balancing Virtual Servers to the right. Click Create.

Horizon Connection Server Locked.properties File

Horizon Connection Server’s default security settings might prevent you from connecting to load balanced Connection Servers and/or Unified Access Gateways. On the Connection Servers, go to C:\Program Files\VMware\VMware View\Server\sslgateway\conf, edit or create locked.properties file, and enter the following:

allowUnexpectedHost=true
checkOrigin=false
enableCORS=false

More details at VMware 2144768 Accessing the Horizon View Administrator page displays a blank error window in Horizon and 85801 Cross-Origin Resource Sharing (CORS) with Horizon 8 and loadbalanced HTML5 access. allowUnexpectedHost defaults to false in Horizon 2306 and Horizon 2212.1 and newer. Another option is to add portalHost entries as detailed at Allow HTML Access Through a Gateway at VMware Docs.

Load Balancing CLI Commands

Internal Connection Server Load Balancing

add server VCS01 10.2.2.19
add server VCS02 10.2.2.20
add serviceGroup svcgrp-VCS-SSL SSL_BRIDGE
add lb vserver lbvip-Horizon-SSL SSL_BRIDGE 10.2.5.203 443 -persistenceType SOURCEIP -timeout 600
bind lb vserver lbvip-Horizon-SSL svcgrp-VCS-SSL
add lb monitor Horizon-SSL HTTP -respCode 200 -httpRequest "GET /favicon.ico" -destPort 443 -secure YES
bind serviceGroup svcgrp-VCS-SSL VCS01 443
bind serviceGroup svcgrp-VCS-SSL VCS02 443
bind serviceGroup svcgrp-VCS-SSL -monitorName Horizon-SSL

Unified Access Gateway load balancing with Blast and PCoIP

add server UAG01 10.2.2.187
add server UAG02 10.2.2.188
add serviceGroup svcgrp-Horizon-SSL SSL_BRIDGE
add serviceGroup svcgrp-Horizon-UDP443 UDP
add serviceGroup svcgrp-Horizon-PCoIPTCP TCP
add serviceGroup svcgrp-Horizon-PCoIPUDP UDP
add serviceGroup svcgrp-Horizon-TCP8443 SSL_BRIDGE
add serviceGroup svcgrp-Horizon-UDP8443 UDP
add lb vserver lbvip-Horizon-SSL SSL_BRIDGE 10.2.5.204 443
add lb vserver lbvip-Horizon-UDP443 UDP 10.2.5.204 443
add lb vserver lbvip-Horizon-PCoIPUDP UDP 10.2.5.204 4172
add lb vserver lbvip-Horizon-PCoIPTCP TCP 10.2.5.204 4172
add lb vserver lbvip-Horizon-8443SSL SSL_BRIDGE 10.2.5.204 8443
add lb vserver lbvip-Horizon-8443UDP UDP 10.2.5.204 8443
bind lb vserver lbvip-Horizon-SSL svcgrp-Horizon-SSL
bind lb vserver lbvip-Horizon-UDP443 svcgrp-Horizon-UDP443
bind lb vserver lbvip-Horizon-PCoIPTCP svcgrp-Horizon-PCoIPTCP
bind lb vserver lbvip-Horizon-PCoIPUDP svcgrp-Horizon-PCoIPUDP
bind lb vserver lbvip-Horizon-8443SSL svcgrp-Horizon-TCP8443
bind lb vserver lbvip-Horizon-8443UDP svcgrp-Horizon-UDP8443
add lb group Horizon -persistenceType SOURCEIP -timeout 600
bind lb group Horizon lbvip-Horizon-SSL
bind lb group Horizon lbvip-Horizon-UDP443
bind lb group Horizon lbvip-Horizon-PCoIPUDP
bind lb group Horizon lbvip-Horizon-PCoIPTCP
bind lb group Horizon lbvip-Horizon-8443SSL
bind lb group Horizon lbvip-Horizon-8443UDP
set lb group Horizon -persistenceType SOURCEIP -timeout 600
add lb monitor Horizon-SSL HTTP -respCode 200 -httpRequest "GET /favicon.ico" -destPort 443 -secure YES -trofscode 503
add lb monitor Horizon-PCoIP TCP -LRTM DISABLED -destPort 4172 -secure YES
add lb monitor Horizon-Blast TCP -LRTM DISABLED -destPort 8443 -secure YES
bind serviceGroup svcgrp-Horizon-SSL UAG01 443
bind serviceGroup svcgrp-Horizon-SSL UAG02 443
bind serviceGroup svcgrp-Horizon-SSL -monitorName Horizon-SSL
bind serviceGroup svcgrp-Horizon-SSL -monitorName Horizon-PCoIP
bind serviceGroup svcgrp-Horizon-SSL -monitorName Horizon-Blast
bind serviceGroup svcgrp-Horizon-UDP443 UAG01 443
bind serviceGroup svcgrp-Horizon-UDP443 UAG02 443
bind serviceGroup svcgrp-Horizon-UDP443 -monitorName Horizon-SSL
bind serviceGroup svcgrp-Horizon-PCoIPTCP UAG01 4172
bind serviceGroup svcgrp-Horizon-PCoIPTCP UAG02 4172
bind serviceGroup svcgrp-Horizon-PCoIPTCP -monitorName Horizon-PCoIP
bind serviceGroup svcgrp-Horizon-PCoIPUDP UAG01 4172
bind serviceGroup svcgrp-Horizon-PCoIPUDP UAG02 4172
bind serviceGroup svcgrp-Horizon-PCoIPUDP -monitorName Horizon-PCoIP
bind serviceGroup svcgrp-Horizon-TCP8443 UAG01 8443
bind serviceGroup svcgrp-Horizon-TCP8443 UAG02 8443
bind serviceGroup svcgrp-Horizon-TCP8443 -monitorName Horizon-Blast
bind serviceGroup svcgrp-Horizon-UDP8443 UAG01 8443
bind serviceGroup svcgrp-Horizon-UDP8443 UAG02 8443
bind serviceGroup svcgrp-Horizon-UDP8443 -monitorName Horizon-Blast

Citrix Director Load Balancing – Citrix ADC

Last Modified: Mar 9, 2022 @ 4:21 pm

25 Comments

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Change Log

  • 2018 Dec 20 – updated screenshots for ADC 12.1 build 50.
  • 2017 Dec 25 – updated entire article for 12.0 build 56. Monitor section has new 12.0 build 56 instructions.

Monitor

12.0 build 56 and newer

Instructions for creating the monitor changed in 12.0 build 56 and newer. If your build is older, skip to the older instructions.

  1. On the left, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name it Director or similar.
  4. In the Type field, click where it says Click to select.
  5. Scroll down and click the circle next to HTTP.
  6. At the top of the window, click the blue Select button.
  7. Scroll down the Basic  Parameters section, and check the box next to Secure. This checkbox instructs the monitor to connect to the Director Servers using https/SSL/TLS instead of http.
  8. In the HTTP Request box, enter GET /Director/LogOn.aspx?cc=true.
  9. If Single Sign-on (Windows Integrated Authentication) is enabled on Director, then you might have to add 302 as a Response Code.
  10. Scroll down, and click Create.
  11. Jump to the Servers section.

12.0 older than build 56

  1. On the left, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name it Director or similar.
  4. Change the Type drop-down to HTTP.
  5. If you will use SSL to communicate with the Director servers, then on the Standard Parameters tab, scroll down, and check the box next to Secure.
  6. Scroll up, and switch to the Special Parameters tab.
  7. In the HTTP Request field, enter GET /Director/LogOn.aspx?cc=true
    1. If Single Sign-on is enabled on Director, then you might have to add 302 as a Response Code.
  8. Scroll down, and click Create.

Servers

  1. On the left, expand Traffic Management, expand Load Balancing, and click Servers.
  2. On the right, click Add.
  3. Enter a descriptive server name. Usually it matches the actual server name.
  4. Enter the IP address of the Director server.
  5. Enter comments to describe the server. Click Create.
  6. Continue adding Director servers.

Service Group

  1. On the left, expand Traffic Management, expand Load Balancing, and click Service Groups.
  2. On the right, click Add.
  3. Give the Service Group a descriptive name (e.g. svcgrp-Director-SSL).
  4. Change the Protocol to HTTP or SSL, depending on if IIS on the Director server is enabled for https or not.
    • If the protocol is SSL, ensure the Monitor for Director has Secure enabled, as detailed earlier.
  5. Scroll down, and click OK.

  6. On the left, in the Service Group Members section, click where it says No Service Group Member.

    1. Change the selection to Server Based, and then Click to select the Director server objects.

    2. Enter 80 or 443 as the port. Then click Create.
  7. Click OK to close the Service Group Members section.
  8. On the right, under Advanced Settings, click Monitors.
  9. On the left, in the Monitors section, click where it says No Service Group to Monitor Binding.

    1. Click where it says to Click to select.
    2. Click the circle next to the Director monitor you created earlier. The monitor might be on Page 2.
      • The circle must be clicked exactly (no room for error). If you click outside the circle, then the monitor will open for editing. If this happens, click Close to return to the selection screen.
    3. At the top of the window, click the blue Select button.
    4. Then click Bind.
  10. To verify that the monitor is working, on the left, in the Service Group Members section, click the Service Group Members line.
  11. Right-click a member, and click Monitor Details.
  12. The Last Response should be Success – HTTP response code 200 received. Click Close twice.
  13. Then click Done.

Responder

Create a Responder policy to redirect users from the root page to /Director.

  1. Go to AppExpert > Responder, and enable the feature if it isn’t already enabled.
  2. Go to AppExpert > Responder > Actions.
  3. On the right, click Add.

    1. Give the Action a name (e.g. Director_Redirect).
    2. Change the Type to Redirect.
    3. In the Expression box, enter "/Director", including the quotes.
  4. On the bottom, click Create.
  5. Go to AppExpert > Responder > Policies.
  6. On the right, click Add.

    1. Give the Policy a name (e.g. Director_Redirect).
    2. Select the previously created Action.
    3. In the Expression box, enter HTTP.REQ.URL.PATH.EQ("/")
  7. On the bottom, click Create.

Load Balancing Virtual Server

  1. Create or install a certificate that will be used by the SSL Virtual Server. This certificate must match the DNS name for the load balanced Director servers.
  2. On the left, under Traffic Management > Load Balancing, click Virtual Servers.
  3. On the right, click Add.
  4. Do the following in the Basic Settings section:
    1. Name it lbvip-Director-SSL or similar.
    2. Change the Protocol to SSL.
    3. Specify a new internal VIP.
    4. Enter 443 as the Port.
    5. Click OK to close the Basic Settings section.
  5. On the left, in the Services and Service section, click where it says No Load Balancing Virtual Server ServiceGroup Binding.

    1. Click where it says Click to select.
    2. Click the circle next to a previously created Service Group. It might be on page 2.
      • The circle must be clicked exactly (no room for error). If you click outside the circle, then the Service Group will open for editing. If this happens, click the x on the top right, or the Done button on the bottom, to return to the selection screen.
    3. At top of the screen, click the blue Select button.
    4. Click Bind.
  6. Click Continue to close the Services and Service Groups section.
  7. Click where it says No Server Certificate.

    1. Click where it says Click to select.
    2. Click the circle next to a certificate that matches the FQDN that resolves to this VIP. It might be on page 2.
    3. At the top of the window, click the blue Select button.
    4. Click Bind.
  8. Click Continue to close the Certificate section.
  9. On the right, in the Advanced Settings column, click Persistence.
  10. On the left, in the Persistence section, do the following:
    1. Change the Persistence drop-down to COOKIEINSERT. The Persistence section in 12.0 build 56 and newer is slightly different than older builds.
    2. Set the Time-out to 0 minutes. This makes it a session cookie instead of a persistent cookie.
    3. Set the Backup Persistence to SOURCEIP.
    4. Set the Backup Time-out to match the timeout of Director. The default timeout for Director is 245 minutes.
    5. The IPv4 Netmask should default to 32 bits.
    6. Click OK to close the Persistence section.
  11. On the right, in the Advanced Settings section, add the Policies section.
  12. On the left, in the Policies section, click the plus icon.

    1. Change the Choose Policy drop-down to Responder, and click Continue.
    2. Click to select the previously created Director_Redirect policy.

      • The circle next to the Responder policy must be clicked exactly (no room for error). If you click outside the circle, then the policy will open for editing. If this happens, click Close to return to the selection screen.
    3. After selecting, click Bind.
  13. If you haven’t enabled the Default SSL Profile, then perform other normal SSL configuration including: disable SSLv3, bind a Modern A+ Cipher Group, and enable Strict Transport Security.

SSL Redirect

Do one of the following to configure a redirect from HTTP to HTTPS:

SSL Warning

  1. If you are doing SSL Offload (SSL on front end, HTTP on back end), when connecting to Director, it might complain about “You are not using a secure connection”.
  2. To turn off this warning, login to the Director servers, and run IIS Manager.
  3. On the left, navigate to Server > Sites > Default Web Site > Director.
  4. In the middle, double-click Application Settings.
  5. Change UI.EnableSslCheck to false.

CLI Commands

Here is a list of NetScaler CLI commands for Director Load Balancing:

# SSL Global Parameters
set ssl parameter -denySSLReneg NONSECURE

# Certs
add ssl certKey WildcardCorpLocal -cert WildcardCorpLocal.pfx -key WildcardCorpLocal.pfx -inform PFX -passcrypt "Passw0rd"

# SSL Cipher Group
add ssl cipher custom-ssllabs-cipher
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-ECDHE-RSA-AES256-GCM-SHA384 -cipherPriority 1
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-ECDHE-RSA-AES128-GCM-SHA256 -cipherPriority 2
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-ECDHE-RSA-AES-256-SHA384 -cipherPriority 3
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-ECDHE-RSA-AES-128-SHA256 -cipherPriority 4
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-ECDHE-RSA-AES256-SHA -cipherPriority 5
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-ECDHE-RSA-AES128-SHA -cipherPriority 6
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-DHE-RSA-AES256-GCM-SHA384 -cipherPriority 7
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1.2-DHE-RSA-AES128-GCM-SHA256 -cipherPriority 8
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-DHE-RSA-AES-256-CBC-SHA -cipherPriority 9
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-DHE-RSA-AES-128-CBC-SHA -cipherPriority 10
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-AES-256-CBC-SHA -cipherPriority 11
bind ssl cipher custom-ssllabs-cipher -cipherName TLS1-AES-128-CBC-SHA -cipherPriority 12

# Responder Actions
add responder action Director_Redirect redirect "\"/Director\"" -responseStatusCode 302

# Responder Policies
add responder policy Director_Redirect "HTTP.REQ.URL.PATH.EQ(\"/\")" Director_Redirect

# Load Balancing Global Parameters
enable ns mode FR L3 Edge USNIP PMTUD ULFD
set ns param -cookieversion 1
set ns tcpParam -WS ENABLED -SACK ENABLED
set ns httpParam -dropInvalReqs ON

# Monitors
add lb monitor Director HTTP -respCode 200 302 -httpRequest "GET /Director/LogOn.aspx?cc=true" -LRTM DISABLED -secure YES

# Servers
add server Director01 xdc01.corp.local
add server Director02 xdc02.corp.local

# Service Groups
add serviceGroup svcgrp-Director-SSL SSL -maxClient 0 -maxReq 0 -cip DISABLED -usip NO -useproxyport YES -cltTimeout 180 -svrTimeout 360 -CKA NO -TCPB NO -CMP YES
bind serviceGroup svcgrp-Director-SSL Director01 443
bind serviceGroup svcgrp-Director-SSL Director02 443
bind serviceGroup svcgrp-Director-SSL -monitorName Director

# Load Balancing Virtual Servers
add lb vserver lbvip-Director-SSL SSL 10.2.5.210 443 -persistenceType COOKIEINSERT -timeout 0 -persistenceBackup SOURCEIP -backupPersistenceTimeout 245 -cltTimeout 180 -redirectFromPort 80 -httpsRedirectUrl "https://director.corp.com"
bind lb vserver lbvip-Director-SSL svcgrp-Director-SSL
bind lb vserver lbvip-Director-SSL -policyName Director_Redirect -priority 100 -gotoPriorityExpression END -type REQUEST

# SSL Virtual Servers
set ssl vserver lbvip-Director-SSL -ssl3 DISABLED -HSTS ENABLED -maxage 157680000
unbind ssl vserver lbvip-Director-SSL -cipherName ALL
bind ssl vserver lbvip-Director-SSL -cipherName custom-ssllabs-cipher
bind ssl vserver lbvip-Director-SSL -certkeyName WildcardCorpLocal
bind ssl vserver lbvip-Director-SSL -eccCurveName P_256
bind ssl vserver lbvip-Director-SSL -eccCurveName P_384
bind ssl vserver lbvip-Director-SSL -eccCurveName P_224
bind ssl vserver lbvip-Director-SSL -eccCurveName P_521

Global Server Load Balancing (GSLB) – Citrix ADC

Last Modified: Mar 30, 2023 @ 10:18 am

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GSLB Planning

GSLB is nothing more than DNS. GSLB receives a DNS query, and then GSLB sends back an IP address, which is exactly how a DNS server works. The user then connects to the returned IP, which doesn’t even need to be on a NetScaler ADC.

GSLB can do some things that DNS servers can’t do:

  • Don’t give out an IP address unless it is UP (monitoring)
    • If the active IP address is down, then give out the passive IP address (active/passive) instead
  • Give out the IP address that is closest to the user (proximity load balancing)
  • Give out different IPs for internal users vs external users (DNS View)

GSLB is only useful if you have a single DNS name that could resolve to two or more IP addresses. If there’s only one IP address, then use normal DNS instead.

Citrix Blog Post Global Server Load Balancing: Part 1 explains how DNS queries work and how GSLB fits in.

Citrix has a good DNS and GSLB Primer.

When configuring GSLB, don’t forget to ask “where is the data?”. See Citrix Blog Post XenDesktop, GSLB & DR – Everything you think you know is probably wrong!

GSLB Configuration Overview

GSLB Configuration can be split between one-time steps for GSLB infrastructure, and repeatable steps for each GSLB-enabled DNS name.

One-time GSLB Infrastructure configuration

  1. Create ADNS listener on each ADC pair – DNS clients send DNS queries to the ADNS listeners. GSLB resolves a DNS query into an IP address, and returns the IP address in the DNS response.
  2. Create GSLB Sites (aka MEP Listener) – GSLB Sites usually correspond to different datacenters. GSLB Sites are also the IP address endpoints for Citrix ADC’s proprietary Metric Exchange Protocol (MEP), which is used by GSLB to transmit proximity, persistence, and monitoring information.
  3. Import Static Proximity Database – Citrix ADC includes a database that can be used to determine the geographical location of an IP address. Or you can subscribe to a geolocation service, and import its database.
  4. Delegate DNS sub-zone to ADC ADNS – in the original DNS zone, create a new sub-zone (e.g. gslb.company.com), and delegate the sub-zone to all ADNS listeners.

Repeatable GSLB Configuration for each DNS name:

  1. Create one or more GSLB Services per DNS name, and per IP address response – each GSLB Service corresponds to a single IP address that can be returned in response to a DNS Query.
    • Optionally, bind a Monitor to each GSLB Service. Monitors determine if the GSLB Service is up or not.
  2. Create a GSLB Virtual Server per DNS name
    • Bind a DNS name to the GSLB Virtual Server.
    • For active/active – bind multiple GSLB Services to the GSLB Virtual Server, configure a load balancing method (e.g. proximity), and configure site persistence.
    • For active/passive – bind the active GSLB Service. Create another GSLB Virtual Server with passive GSLB Service and configure as Backup Virtual Server.
      • Alternatively, NetScaler ADC 13.1 and newer let you bind GSLB Services in priority order. See Citrix Docs for details.
  3. Create CNAME records for each delegated DNS name – in the main DNS zone, create a CNAME that maps the original DNS name to the delegated sub-zone. For example, CNAME citrix.company.com to citrix.gslb.company.com.

You will create separate GSLB Services, separate GSLB Virtual Servers, and separate CNAMEs for each DNS name. If you have a bunch of DNS names that you want to GSLB-enable, then you’ll repeat these steps for each GSLB-enabled DNS name.

Each datacenter has a separate ADNS listener IP address. DNS is delegated to all GSLB ADNS Listener IPs, and any one of them can respond to the DNS query. Thus, all ADC pairs participating in GSLB should have the same Per-DNS name configuration.

One ADC appliance for both public DNS/GSLB and internal DNS/GSLB?

GSLB can be enabled both publically and internally. For public GSLB, configure it on DMZ ADC appliances, and expose the DNS listener to the Internet. For internal GSLB, configure it on separate internal ADC appliances/instances, and create an internal DNS listener.

Each ADC appliance only has one DNS table, so if you try to use the same ADC for both public DNS and internal DNS, then be aware that external users can query for internal GSLB-enabled DNS names.

  • As described by Phil Bossman in the comments, you can use a Responder policy to prevent external users from reading internal DNS names. 
    add policy patset GSLB_INTERNAL
bind policy patset GSLB_INTERNAL internalHostname.gslb.domain.com -index 1
add responder action DNS_Empty_Response respondwith DNS.NEW_RESPONSE
add responder policy GSLB_DNS_Empty_Response "(!(CLIENT.IP.SRC.IN_SUBNET(10.0.0.0/8)||CLIENT.IP.SRC.IN_SUBNET(192.0.0.0/16)||CLIENT.IP.SRC.IN_SUBNET(172.0.0.0/12)) && DNS.REQ.QUESTION.DOMAIN.CONTAINS_ANY(\"GSLB_INTERNAL\"))" DNS_Empty_Response
bind responder global GSLB_DNS_Empty_Response 100 END -type DNS_REQ_DEFAULT

One appliance resolving a single DNS name differently for internal and public

Let’s say you have a single DNS name citrix.company.com. When somebody external resolves the name, it should resolve to a public IP. When somebody internal resolves the name, it should resolve to an internal IP.

For internal GSLB and external GSLB of the same DNS name on the same ADC appliance, you can use DNS Policies and DNS Views to return different IP addresses depending on where users are connecting from. See Citrix CTX130163 How to Configure a GSLB Setup for Internal and External Users Using the Same Host Name.

If the Internet circuit in the remote datacenter goes down, then this should affect public DNS, since you don’t want to give out a public IP that isn’t reachable. But do you also want an Internet outage to affect internal DNS? Probably not. In that case, you would need different GSLB monitoring configurations for internal DNS and external DNS. However, if you have only a single GSLB Virtual Server with DNS Views, then you can’t configure different monitoring configurations for each DNS View.

To work around this limitation, create two separate GSLB Virtual Servers with different monitoring configurations. Internal DNS uses a CNAME record to reach the GSLB Virtual Server configured for internal monitoring:

  • External citrix.company.com:
    • Configure ADC GSLB for citrix.company.com.
    • On public DNS, delegate citrix.company.com to the ADC DMZ ADNS services.
  • Internal citrix.company.com:
    • Configure ADC GSLB for citrixinternal.company.com or something like that.
    • On internal DNS, create CNAME for citrix.company.com to citrixinternal.company.com
    • On internal DNS, delegate citrixinternal.company.com to ADC internal ADNS services.

Remote Internet Monitoring

For public DNS/GSLB, you don’t want to give out a remote public IP address if that remote public IP address is not reachable. That means the local ADC will need to somehow determine if the remote datacenter has Internet connectivity or not. Here are some methods of verifying the remote Internet connection:

  • Route GSLB Metric Exchange Protocol (MEP) across the Internet. If MEP goes down, then all IP addresses associated with the remote GSLB Site are assumed to be down, and thus the local ADC will stop giving out those remote IP addresses.
  • Bind explicit monitors to each GSLB Service, and ensure the monitoring is routed across the Internet.

GSLB IP Addresses

GSLB is separate from data traffic. The GSLB IP addresses are separate from the IP addresses needed for data.

Some GSLB-specific IP Addresses are needed on each ADC pair:

  • ADNS Listener IP: An ADC IP that listens for DNS queries.
    • The ADNS listener IP is typically an existing SNIP on the appliance.
    • For external DNS, create a public IP for the ADNS Listener IP, and open UDP 53 and TCP 53, so Internet-based DNS servers can access it.
    • A single ADC appliance can have multiple ADNS listeners – typically one ADNS listener for public, and another ADNS listener for internal.
  • GSLB Site IP / MEP listener IP: An ADC IP that will be used for ADC-to-ADC GSLB communication. This communication is called MEP or Metric Exchange Protocol. MEP transmits the following between GSLB-enabled ADC pairs: load balancing metrics, proximity, persistence, and monitoring.
    • GSLB Sites – On ADC, you create GSLB Sites. GSLB Sites are the endpoints for the MEP communication. Each ADC pair is configured with the MEP endpoints for the local appliance pair, and all remote appliance pairs.
    • TCP Ports – MEP uses port TCP 3009 or TCP 3011 between the ADC pairs. TCP 3009 is encrypted.
    • The ADNS IP address can be used as the MEP endpoint IP.
    • MEP endpoint can be any IP – The MEP endpoint IP address can be any IP address and does not need to be a SNIP or ADNS.
    • One MEP IP per appliance – there can only be one MEP endpoint IP address on each ADC pair.
    • Route MEP across Internet? – If you route MEP across the Internet, and if the MEP connection is interrupted, then Internet at one of the locations is probably not working. This is an easy way to determine if remote Internet is up or not. If you don’t route MEP across the Internet, then you’ll need to configure every remote-site GSLB Service with a monitor to ensure that the remote Internet is up.
      • Public IPs for MEP Enpoints – if you route MEP across the Internet, then you’ll need public IPs for each publically-accessible MEP endpoint IP address.
      • Public Port for MEP: Open port TCP 3009 between the MEP Public IPs. Make sure only the MEP IPs can access this port on the other ADC . Do not allow any other device on the Internet to access this port. Port 3009 is encrypted.
    • GSLB Sync Ports: To use GSLB Configuration Sync, open ports TCP 22 and TCP 3008 (secure) from the NSIP (management IP) to the remote public MEP IP. The GSLB Sync command runs a script in BSD shell and thus NSIP is always the Source IP.
  • Public IP Summary: In summary, for public GSLB, if MEP and ADNS are listening on the same IP, then you need one new public IP that is NAT’d to the DMZ IP that is used for ADNS and MEP (GSLB Site IP).
    • Each datacenter has a separate public IP.
    • DNS is delegated to all public ADNS IP listeners.

GSLB Wizard

NetScaler 12 and Citrix ADC 12.1 and newer have a GSLB Wizard at Traffic Management > GSLB.

However, the wizard doesn’t really save any time or steps, so it won’t be documented here.

ADNS Listener

  1. At System > Network > IPs, identify a Citrix ADC-owned IP that you will use as the ADNS listener. This is typically a SNIP.
  2. Create a public IP for the ADNS Service IP and configure firewall rules. UDP 53 and TCP 53 need to be opened from the Internet to the public IP that NATs to the ADNS Listener IP address.
  3. On the left, expand Traffic Management > Load Balancing, and click Services.
  4. On the right, click Add.

    1. In the Basic Settings section, do the following:
      1. Name the service ADNS or similar.
      2. In the IP Address field, enter an appliance SNIP.
      3. In the Protocol drop-down, select ADNS.
    2. Click OK.
    3. No other configuration is needed so scroll down and click Done to close the Load Balancing Service properties.
  5. Highlight the ADNS service you just added and then click Add to create another Service while copying some of the settings from the previously created Service.

    1. Change the Service Name to ADNS_TCP or similar.
    2. Change the Protocol drop-down to ADNS_TCP.
    3. Click OK to close the Basic Settings section.
    4. No other configuration is needed so scroll down and click Done to close the Load Balancing Service properties.
  6. You should have two ADNS services on the same IP address: one for ADNS, and one for ADNS_TCP.
  7. On the left of the console in the menu, expand System, expand Network, and then click IPs.
  8. On the right, you’ll see the SNIP is now marked as the ADNS svc IP.
  9. Repeat the ADNS configuration on the other appliance pair in the other datacenter. Except the other appliance will use its own SNIP as the ADNS Service listener IP address.
  10. Your ADC appliances are now DNS servers.

DNS Security

  1. Citrix ADC includes DNS Security Options, at Security > DNS Security, which can protect your ADNS service.
  2. To protect ADNS, set the Profile to All DNS Endpoints.

Metric Exchange Protocol

This section details MEP configuration between two GSLB Sites. See Citrix Docs for larger Parent-Child Topology Deployment Using the MEP Protocol.

GSLB Sites

  1. The local GSLB Site IP can be any IP, including the same SNIP that you used for ADNS.
  2. Open the firewall rules for Metric Exchange Protocol. The GSLB Site IP on this appliance pair uses TCP 3009 to communicate with the GSLB Site IP on the other appliance pair.
  3. On the left, expand Traffic Management, right-click GSLB, and enable the feature.
  4. Expand GSLB, and click Sites.
  5. On the right, click Add.
  6. In the Create GSLB Site page, do the following:
    1. We’re adding the local site first. Enter a descriptive name for the local site.
    2. In the Site Type drop-down, select LOCAL.
    3. In the Site IP Address field, enter an IP that this appliance will listen for MEP traffic. This is typically a SNIP and can the same as your ADNS IP.
    4. For Internet-routed GSLB MEP, in the Public IP Address field, enter the public IP that is NAT’d to the GSLB Site IP.
    5. For internal GSLB MEP, there is no need to enter anything in the Public IP field.
  7. Scroll down, and click Create, to close the Create GSLB Site page.

  8. Go back to System > Network > IPs, and notice that the IP is now marked as a GSLB site IP.
  9. If you want to use the GSLB Sync Config feature, then you’ll need to edit the GSLB site IP, and enable Management Access.

    1. Scroll down, and enable Management Access. SSH is all you need.
  10. Go to the other appliance pair, and also create the Local GSLB site using its GSLB site IP, and its public IP that is NAT’d to the GSLB site IP.

    1. In System > Network > IPs on the remote appliance, there should now be a GSLB site IP. If GSLB Sync is desired, enable management access on that IP and ensure SSH is enabled.
  11. Now on each appliance, add another GSLB Site, which will be the Remote GSLB site.
  12. In the Create GSLB Site page, do the following:
    1. Enter a descriptive name for the remote site.
    2. Select REMOTE as the Type.
    3. Enter the other appliance’s actual GSLB Site IP as configured on the appliance. This IP does not need to be reachable.
    4. In the Public IP Address field, enter the public IP that is NAT’d to the GSLB Site IP on the other appliance. For MEP, TCP 3009 must be open from the local GSLB Site IP, to the remote public Site IP. For GSLB sync, TCP 22, and TCP 3008, must be open from the local NSIP, to the remote public Site IP.
  13. Click Create.
  14. Repeat on the other appliance.

RPC

MEP defaults to unencrypted on TCP 3011. To fix that:

  1. On the left, expand System, expand Network, and click RPC.
  2. On the right, right-click the new RPC address (the other site’s GSLB Site IP), and click Edit.
  3. On the bottom, check the box next to Secure. In ADC 13.0 64.x and 12.1 build 61.x onwards, Secure is enabled by default. (source = Citrix CTX292743 Configuration Sync, Propagation and MEP Propagation Might Fail After Upgrade to 13.0 64.x\12.1 61.x)

    • If your local GSLB Site IP is not a SNIP, then you’ll need to change the RPC Node to use the local GSLB Site IP as the source IP. In the Source IP Address field, enter the local GSLB Site IP.
  4. Click OK when done.
  5. Do the same thing on the other appliance.
  6. If you go back to GSLB > Sites, you should see it as active.

See Citrix Tech Zone Troubleshooting Citrix GSLB MEP Cheat Sheet

If your MEP connection between GSLB Sites flaps, it might be useful to introduce a delay before remote GSLB Services are marked as Down.

  1. You can do this at Traffic Management > GSLB > Dashboard.
  2. On the right, click Change GSLB settings.
  3. In the GSLB Service State Delay Time (secs) field, enter a delay before the GSLB Services are marked as down when MEP goes down.

    set gslb parameter -GSLBSvcStateDelayTime 15

Static Proximity Geo Location Database

If you want to use DNS Policies, or Static Proximity GSLB Load Balancing, or Responders based on user’s location, import a geo location database.

Citrix ADC has a built-in database at /var/netscaler/inbuilt_db/ that you can use. Or you can download a database. Common free databases are:

For IP2Location, see the blog post Add IP2Location Database as NetScaler’s Location File for instructions on how to import.

CTX235799 NetScaler data formats for Location Database Import

Citrix Github has a Citrix-ADC-GSLB-GeoIP-Conversion-Tool that can convert Maxmind GeoIP City database to Citrix ADC (NetScaler) format.

Import the Built-in Geo database:

  1. In the Citrix ADC GUI, on the left, expand Traffic Management, expand GSLB, expand Database and Entries, and click Static Databases.
  2. On the right, click Add.
  3. Change the Import From selection to File.
  4. Click Choose File.
  5. Browse to /var/netscaler/inbuilt_db/. To browse to the directory, select var, and then click Open.
  6. Repeat for each directory until you reach /var/netscaler/inbuilt_db.
  7. In ADC 12.1, you can select the file named Citrix_Netscaler_InBuild_GeoIP_DB_IPv4. In NetScaler 12.0, select the only file shown. Then click Open.
  8. In the Location Format field, if using the built-in database, select netscaler, and click Create.
  9. After you later create a GSLB Service, when you open the GSLB Service, the public IP will be translated to a location based on the contents of the static proximity database.

Private IP Blocks

Geo Location databases only contain entries for Public IPs. For Private IPs, do the following:

  1. On the left, expand Traffic Management, expand GSLB, expand Database and Entries, and click Custom Entries.
  2. On the right, click Add.
  3. Enter a range of IP addresses for a particular location.
  4. Enter a Location Name in Geo Location format, which is typically six location words separated by periods. You can look in the static proximity database for examples.
  5. Make sure you enter coordinates. Google can find you coordinates for cities.
  6. Click Create.
  7. Continue creating Custom Entries for other private IP blocks.

Use Geo Locations

You can use the Geo locations in a DNS Policy, static proximity GSLB Load Balancing, Responders, and Rewrites:

Prior to Citrix ADC 12.1 build 50, the only option in policy expressions is to match a known location.

Citrix ADC 12.1 build 50 and newer lets you extract the user’s location and use it in policy expressions.

GSLB Services

GSLB Services represent the IP addresses that are returned in DNS Responses. The IP addresses represented by GSLB Services do not need to be hosted on a Citrix ADC, but Citrix ADC-owned IP addresses (e.g. load balancing VIPs) have additional GSLB Site Persistence options (e.g. cookie-based persistence).

  • Each potential IP address in a DNS response is a separate GSLB Service.
  • GSLB Services are associated with GSLB Sites.
  • GSLB Service configuration is identical for active/active and active/passive. GSLB Virtual Server configuration defines active/active or active/passive, not GSLB Services.

GSLB should be configured identically on all Citrix ADC pairs that are responding to DNS queries. Since you have no control over which Citrix ADC will receive the DNS query, you must ensure that both Citrix ADC pairs are giving out the same DNS responses.

To create a GSLB Service:

  1. On the left, expand Traffic Management > GSLB, and click Services.
  2. On the right, click Add.
  3. The service name should be similar to the DNS name that you are trying to GSLB. Include the site name in the service name.
  4. Select one of the GSLB Sites. The IP address you’re configuring in this GSLB Service should be geographically located in the selected GSLB Site.
  5. On the bottom part, if the IP address is owned by this Citrix ADC, then select Virtual Servers, and select a Virtual Server that is already defined on this appliance. It should automatically fill in the other fields. This option is only available when creating a GSLB Service in the Local GSLB Site.

    1. If the IP address is not owned by this Citrix ADC, then change the selection to New Server, and enter the remote IP address in the Server IP field.
    2. The Server IP field is the IP address that Citrix ADC will monitor for reachability.
    3. If the remote IP is owned by a different Citrix ADC that is reachable by MEP, then enter the actual VIP configured on that remote Citrix ADC. The Server IP does not need to match what is returned to the DNS Query.
  6. In the Public IP field, enter the IP address that will be returned to the DNS Query. If you leave Public IP blank, then Citrix ADC will copy the Server IP to the Public IP field. For Public GSLB, the Public IP field is usually a Public IP address. For internal GSLB, the Public IP field is usually an internal IP, and probably matches the Server IP.
  7. Scroll up, and make sure the Service Type is SSL. It’s annoying that Citrix ADC doesn’t set this drop-down correctly.
  8. Scroll down, and click OK, to close the Basic Settings section.
  9. GSLB Service Monitoring – on the right, in the Advanced Settings column, you can click Monitors to bind a monitor to this GSLB Service. Review the following notes before you bind a monitor.

    • Local Citrix ADC VIP – If the GSLB Service IP is a VIP on the local appliance, then GSLB will simply use the state of the local traffic Virtual Server (Load Balancing, Content Switching, or Gateway). There’s no need to bind a monitor to the GSLB Service.
    • Remote Citrix ADC VIP – If the GSLB Service IP is a VIP on a remote appliance, then GSLB will use MEP to ask the other appliance for the state of the remote traffic Virtual Server. In both cases. There’s no need to bind a monitor to the GSLB Service.
    • GSLB Monitor overrides other Monitoring methods – If you bind a monitor to the GSLB Service, then MEP and local Virtual Server state are ignored (overridden).
    • Here are some reasons for binding a monitor to the GSLB Service:
      • IP is not on a Citrix ADC– If the GSLB Service IP is not hosted on a Citrix ADC, then only a monitor can determine if the Service IP is up or not.
      • Monitor remote Internet – For Public DNS, if MEP is not routed through the Internet, then you need some method of determining if the remote Internet circuit is up or not. In that case, you’ll need to bind monitors directly to the GSLB Service. The route of the Monitor should go across the Internet. Or you can ping the Internet router in the remote datacenter to make sure it’s reachable.
      • Traffic Domains – If the GSLB Service IP is in a non-default Traffic Domain, then you will need to attach a monitor, since GSLB cannot determine the state of Virtual Servers in non-default Traffic Domains.
      • TCP monitor – for TCP services (not UDP), a simple TCP monitor is probably all you need. The TCP monitor tries to connect to the GSLB Service Public IP address using the SNIP of the local appliance. Make sure firewall on both sides allows this connection.
  10. Active/Active Site Persistence – If you intend to do GSLB active/active, and if you need site persistence, then on the right you can add Site Persistence and enable Connection Proxy or HTTP Redirect. See Citrix Blog Post Troubleshooting GSLB Persistence with Fiddler for more details. This only works with GSLB Service IPs that match Virtual Server VIPs on Citrix ADC appliances reachable through MEP.

  11. Scroll down, and click Done, to finish creating the GSLB Service.
  12. Create additional GSLB Services for each IP address that will be returned to a DNS query. There should be at least two for each DNS name.
  13. When creating a GSLB Service, select the correct Site, and make sure Service Type = SSL.
  14. The State will probably be down until the other ADC is configured.

Manually Synchronize GSLB Configuration

Copy the GSLB Service Configuration to the remote Citrix ADC pair. You can either repeat the GUI steps listed above. Or you can do the following:

  1. On the left, expand Traffic Management, expand GSLB, and click Dashboard.
  2. On the right, click View GSLB Configuration.
  3. This shows you all of the CLI commands for GSLB. Look for add gslb service commands. You can copy them, and run them (SSH) on other Citrix ADC pairs that are participating in GSLB.

GSLB Virtual Server

GSLB Virtual Server is the entity that links a DNS name with GSLB Services.

For Active/Passive GSLB in NetScaler ADC 13.1 or newer, GSLB Services can be bound in priority order. GSLB will give out the IP address of the lowest order GSLB Service. If that GSLB Service is down, then GSLB will give out the IP address of the next order GSLB Service.

  1. Create a GSLB Virtual Server.
  2. Bind the active GSLB Service but set the Order to 1.
  3. Bind the passive GSLB Service but set the Order to 2.
  4. Bind a DNS name to the GSLB Virtual Server.
  5. Repeat the GSLB Virtual Server configuration on other Citrix ADC pairs participating in GSLB.
  6. Delegate the DNS name to Citrix ADC ADNS.

For Active/Passive GSLB, the Active GSLB Virtual Server will give out a single IP address if that IP address up. If the GSLB Service is down, then it will fail over to a Backup GSLB Virtual Server that gives out a different IP address.

  1. Create a GSLB Virtual Server for the Passive IP address.
    1. Bind the Passive GSLB Service to the Passive GSLB Virtual Server.
  2. Create another GSLB Virtual Server for the Active IP address.
    1. Bind the Active GSLB Service to the Active GSLB Virtual Server.
    2. Configure Backup Virtual Server pointing to the Passive GSLB Virtual Server.
    3. Bind a DNS name to the Active GSLB Virtual Server.
  3. Repeat the GSLB Virtual Server configuration on other Citrix ADC pairs participating in GSLB.
  4. Delegate the DNS name to Citrix ADC ADNS.

For Active/Active GSLB, a single GSLB Virtual Server gives out multiple IP addresses based on load balancing method and site persistence.

  1. Create one GSLB Virtual Server.
    1. Bind two or more GSLB Services to the Virtual Server.
    2. Configure the GSLB Virtual Server Load Balancing Method – e.g., Proximity
    3. Configure Site Persistence:
      1. Source IP persistence is configured on the GSLB Virtual Server.
      2. Cookie Persistence is configured on the GSLB Services.
    4. Bind a DNS name to the GSLB Virtual Server.
  2. Repeat the GSLB Virtual Server configuration on other Citrix ADC pairs participating in GSLB.
  3. Delegate the DNS name to Citrix ADC ADNS.

Configure Active/Passive GSLB in NetScaler ADC 13.1 and newer

  1. On the left, expand Traffic Management, expand GSLB, and click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section, do the following:
    1. Give the GSLB Virtual Server a descriptive name.
    2. Set the Service Type to SSL to match the GSLB Sevices you intend to bind.

      add gslb vserver <gslb_vserver_name> SSL
  4. Click OK to close the Basic Settings section.
  5. On the left, click where it says No GSLB Virtual Server to GSLB Service Binding.

    1. Click where it says Click to select.
    2. Check the box next to the active GSLB Service and click Select.
    3. In the Order box, enter 1. Click Bind.
  6. To add another GSLB Service Binding, on the left, click where it says 1 GSLB Virtual Server to GSLB Service Binding.

    1. Click Add Binding.
    2. Click where it says Click to select.
    3. Check the box next to a passive GSLB Service and then click Select at the top of the page.
    4. In the Order box, enter 2 so that this GSLB Service is only used if all Order 1 GSLB Services are down. Click Bind.
  7. Click OK to close the GSLB Services and GSLB Service Group Binding section.
  8. On the left, click where it says No GSLB Virtual Server Domain Binding.

    1. Enter the FQDN that this GSLB Virtual Server will resolve.
    2. Click Bind.
    3. If you are doing CNAME (e.g., citrix.corp.com CNAME to citrix.gslb.corp.com, then add domain bindings for both the main FQDN and the CNAME FQDN. Click Close when done.
  9. Click OK to close the GSLB Virtual Server Domain Binding section.
  10. Click OK to close the ADNS Service section.
  11. With GSLB Services assigned to different Order numbers, it is not necessary to configure Backup Virtual Server.
  12. If you bound multiple GSLB Services to a single Order number, then you might want to adjust Method and Persistence.
  13. Click Done to finish creating the GSLB Virtual Server.
  14. On the left, if you expand Traffic Management > DNS, expand Records, and click Address Records…
  15. You’ll see a new DNS record for the GSLB domain you just configured. Notice it is marked as GSLB DOMAIN, and has a default TTL of 5 seconds. You can also see which GSLB Virtual Server it is bound to.
  16. Configure an identical GSLB Virtual Server on the other NetScaler ADC appliance pair. Both NetScaler ADC pairs must be configured identically. You can use Traffic Management > GSLB > Dashboard > View GSLB Configuration to copy the add/set/bind gslb vserver commands from this appliance to other NetScaler ADC appliances.


Configure Active/Passive GSLB in NetScaler ADC 13.0 and older

Passive Virtual Server

  1. On the left, expand Traffic Management, expand GSLB, and click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section, do the following:
    1. Give the Passive GSLB Virtual Server a descriptive name.
    2. Set the Service Type to SSL to match the GSLB Services that you will bind to this Virtual Server.
  4. Click OK to close the Basic Settings section.
  5. On the left, click where it says No GSLB Virtual Server to GSLB Service Binding.

    1. Click where it says Click to select.
    2. Check the box next to an existing Passive GSLB Service, and then click the blue Select button at the top of the screen.
    3. Click Bind.
  6. Click OK to close the GSLB Virtual Server GSLB Service Binding section.
  7. Click OK to close the GSLB Virtual Server Domain Binding section. The DNS name is bound to the Active Virtual Server, not the Passive Virtual Sever.
  8. Click OK to close the ADNS Service section.
  9. Click Done to finish creating the Passive GSLB Virtual Server.

Active Virtual Server

  1. On the left, expand Traffic Management, expand GSLB, and click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section, do the following:
    1. Give the Active GSLB Virtual Server a descriptive name.
    2. Set the Service Type to SSL to match the GSLB Services that you will bind to this Virtual Server.
  4. Click OK to close the Basic Settings section.
  5. On the left, click where it says No GSLB Virtual Server to GSLB Service Binding.

    1. Click where it says Click to select.
    2. Check the box next to an existing Active GSLB Service, and click Select.
    3. Click Bind.
  6. Click OK to close the GSLB Virtual Server GSLB Service Binding section.
  7. On the left, click where it says No GSLB Virtual Server Domain Binding.
  8. In the Domain Binding page, do the following:
    1. Enter the FQDN that GSLB will resolve.
    2. Click Bind.
  9. Click OK to close the GSLB Virtual Server Domain Binding section.
  10. Click OK to close the ADNS Service section.
  11. On the right, in the Advanced Settings section, click Backup Virtual Server to add it to the left.
  12. On the left, in the Backup Virtual Server section, select the Passive GSLB Virtual Server, and click OK.
  13. Click Done when done creating the Active GSLB Virtual Server.
  14. On the left, if you expand Traffic Management > DNS, expand Records, and click Address Records…
  15. On the right, you’ll see a new DNS record for the GSLB domain you just configured. Notice the Type is GSLB DOMAIN, and has a default TTL of 5 seconds. You can also see which GSLB Virtual Server it is bound to.
  16. Configure identical GSLB Virtual Servers on the other Citrix ADC appliance pair. Both Citrix ADC pairs must be configured identically. You can use Traffic Management > GSLB > Dashboard > View GSLB Configuration to copy the add/set/bind gslb vserver commands from this appliance to other Citrix ADC appliances.

Configure Active/Active GSLB

  1. On the left, expand Traffic Management, expand GSLB, and click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section, do the following:
    1. Give the GSLB Virtual Server a descriptive name.
    2. Set the Service Type to SSL to match the GSLB Sevices you intend to bind.
    3. You can optionally check the box for Send all “active” service IPs in response (MIR). By default, GSLB only gives out one IP address per DNS query. This checkbox always returns all IPs, but the IPs are ordered based on the GSLB Load Balancing Method and/or GSLB Persistence.
    4. A new DNS feature called ECS will contain the actual DNS client IP. This dramatically improves the accuracy of determining a user’s location. Without this setting, GSLB can only see the IP address of the user’s configured DNS server instead of the real client IP. Check the box next to Respond with ECS option to enable ECS for site persistence.

      set gslb vserver <gslb_vserver> -ECS ENABLED
  4. Click OK to close the Basic Settings section.
  5. On the left, click where it says No GSLB Virtual Server to GSLB Service Binding.

    1. Click where it says Click to select.
    2. Check the boxes next to multiple existing GSLB Services, and click Select.
    3. Click Bind.
  6. Click OK to close the GSLB Virtual Server GSLB Service Binding section.
  7. On the left, click where it says No GSLB Virtual Server Domain Binding.

    1. Enter the FQDN that this GSLB Virtual Server will resolve.
    2. Click Bind.
  8. Click OK to close the GSLB Virtual Server Domain Binding section.
  9. Click OK to close the ADNS Service section.
  10. On the left, in the Method section, click the pencil icon.

    1. For poximity load balancing, change the Choose Method drop-down to RTT with STATICPROXIMITY as backup.
      1. RTT = Round Trip Time. Each ADC appliance sends a ping to the user’s DNS server. Whichever ADC appliance gets the fastest response determines the site of the GSLB Service. RTT requires that ADC be able to ping anything on the Internet so adjust firewall rules accordingly.
      2. STATICPROXIMITY requires that the Geo Location database has already been installed on the appliance.
    2. Click OK to close the Method section.
  11. On the right, in the Advanced Settings column, click Persistence to add it to the left.

    1. On the left, at the bottom of the page in the Persistence section, change the Persistence drop-down to Source IP.
    2. Enter a Persistence Id.
      1. The Persistence ID signifies the persistence table that each ADC pair shares across the MEP connection.
      2. Each active/active GSLB Virtual Server should have a different Persistence ID (different persistence table).
      3. When you configure the same GSLB Virtual Server on each Citrix ADC pair, specify the same Persistence ID so every Citrix ADC has the same persistence information for this particular GSLB Virtual Server.
    3. In the Time-out field, enter the Persistence Time-out. This is typically the same or longer than the webpage timeout.
    4. Click OK to close the Persistence section.
  12. Click Done to finish creating the GSLB Virtual Server.
  13. On the left, if you expand Traffic Management > DNS, expand Records, and click Address Records…
  14. You’ll see a new DNS record for the GSLB domain you just configured. Notice it is marked as GSLB DOMAIN, and has a default TTL of 5 seconds. You can also see which GSLB Virtual Server it is bound to.
  15. Configure an identical GSLB Virtual Server on the other Citrix ADC appliance pair. Both Citrix ADC pairs must be configured identically. You can use Traffic Management > GSLB > Dashboard > View GSLB Configuration to copy the add/set/bind gslb vserver commands from this appliance to other Citrix ADC appliances.


GSLB Configuration Synchronization Script

Manual GSLB Synchronization

  1. The synchronization script requires SSH to be enabled on your GSLB Site IPs.

  2. Ports TCP 3008, TCP 3010, and TCP 22 must be opened from the local NSIP to the remote GSLB Site IP. The source IP is NSIP, not SNIP.
  3. To manually run the script that syncs GSLB configuration from one GSLB Site to another, on the left, expand Traffic Management, expand GSLB, and click Dashboard.
  4. On the right, click the button labelled Auto Synchronization GSLB.
  5. Use the check boxes on the top, if desired. It’s usually a good idea to Preview the changes before applying them.
  6. Then click Run to begin synchronization.
  7. Click Close.
  8. You can Run it again without previewing it. It seems to take several seconds to complete.

Automatic GSLB Synchronization

  1. There is an automatic GSLB Configuration Sync feature, which automatically syncs the GSLB config every 15 seconds. To enable it on the master appliance, go to Traffic Management > GSLB > Dashboard. On the right, click Change GSLB settings.
  2. Check the box next to Automatic Config Sync. Only enable this on the one appliance where you are configuring GSLB, and want that GSLB config synced to other appliance.
  3. The automatic sync log can be found at /var/netscaler/gslb/periodic_sync.log.

Some notes regarding GSLB Sync:

  • When syncing GSLB Services, it tries to create Load Balancing Server objects on the remote appliance. If the GSLB Service IP matches an existing Load Balancing Server object, then the GSLB sync will fail. Check the Sync logs for details. You’ll have to delete the conflicting Load Balancing Server object before GSLB Sync works correctly.
  • GSLB Sync runs as a script on the BSD shell and thus always uses the NSIP as the source IP.
  • GSLB Sync connects to the remote GSLB Site IP on TCP 3008 (if RPC is Secure) and TCP 22.

Test GSLB

  1. You can test GSLB DNS name resolution from the GUI by going to Traffic Management > GSLB > Dashboard, and on the right, click the button labelled Test GSLB.

  2. Select a GSLB Domain Name.
  3. Select an ADNS Service IP to test it from, and click Test.
  4. The test performs a dig against the ADNS IP. Verify that the response contains the IP address you expected.
  5. Another method of testing GSLB is to simply point nslookup to the ADNS services and submit a DNS query for one of the DNS names bound to a GSLB vServer. Run the query multiple times to make sure you’re getting the response you expect.
    • The syntax is “nslookup <DNS_name> <ADNS_IP>”. The second argument specifies the DNS server that you send the DNS Query to.
  6. The Citrix ADC ADNS services at both GSLB sites should be giving the same response.
  7. To simulate a failure, if the GSLB Service IP is a Citrix ADC Load Balancing, Content Switching, or Citrix Gateway IP, you can disable the Virtual Server.
  8. Then the responses should change. Verify on both ADNS services.
  9. Re-enable the Virtual Server, and the responses should return to normal.

DNS Delegation

If you are enabling GSLB for the domain gateway.corp.com, you’ll need to create a delegation at the server that is hosting the corp.com DNS zone. For public GSLB, you need to edit the public DNS zone for corp.com.

DNS Delegation instructions will vary depending on what product is hosting the public DNS zone. This section details Microsoft DNS, but it should be similar in BIND or web-based DNS products.

There are two ways to delegate GSLB-enabled DNS names to Citrix ADC ADNS:

  • Delegate the individual record –  For example, delegate gateway.corp.com.
  • Delegate an entire subzone – For example, delegate the subzone gslb.corp.com. Then create a CNAME record in the parent DNS zone for gateway.corp.com that is aliased to gateway.gslb.corp.com. For additional delegations, simply create more CNAME records.
    • The incoming DNS query to the ADNS listener is for gateway.gslb.corp.com and not gateway.corp.com. You’ll need to bind gateway.gslb.corp.com to your GSLB Virtual Server. You can bind multiple FQDNs to a single GSLB Virtual Server.

A delegation consists of the following DNS records:

  • A records (host records) that resolve to each Citrix ADC ADNS IP address. If you have two ADC pairs participating in GSLB, then you’ll need one A record for each ADC pair.
    • The A record names are typically something like ns1.corp.com and ns2.corp.com, just like you would name any other DNS server.
    • You only create the A records once. The A records for ADNS services can be used by multiple delegations.
    • These A records for ADNS are sometimes called glue records.
  • NS records for each delegation. The NS records point to the A records that resolve to the ADC ADNS IP addresses. If you have two ADC ADNS IP addresses, then you need two NS records for each delegation.
    • When delegating individual records, you create separate NS records for each delegation. If you have two ADNS listeners, then you need two NS records for each delegation.
    • When delegating a subzone, you only need NS records for the subzone. To GSLB-enable a DNS name, you create a CNAME that aliases to a record under the subzone.

Delegate an individual DNS record

  1. Run DNS Manager.
  2. First, create Host Records pointing to the ADNS services running on the Citrix ADC pairs in each data center. These host records for ADNS are used for all GSLB delegations no matter how many GSLB delegations you need to create. These are sometimes called glue records.
  3. The first Host record is gslb1, (or similar) and should point to the ADNS service (Public IP) on one of the Citrix ADC appliances.
  4. The second Host record is gslb2, and should point to the ADNS Service (public IP) on the other Citrix ADC appliance.
  5. If you currently have a host record for the service that you are delegating to GSLB (e.g. gateway.corp.com), delete it.
  6. Right-click the parent DNS zone, and click New Delegation.
  7. In the Welcome to the New Delegation Wizard page, click Next.
  8. In the Delegated Domain Name page, enter the left part of the DNS record that you are delegating (e.g. gateway for gateway.corp.com). Click Next.
  9. In the Name Servers page, click Add.
  10. This is where you specify gslb1.corp.com and gslb2.corp.com as delegated name servers. Enter gslb1.corp.com, and click Resolve. Then click OK. If you see a message about the server not being authoritative for the zone, ignore the message. Note: you only add one name server at a time.
  11. Then click Add to add the other GSLB ADNS server.
  12. Once both ADNS servers are added to the list, click Next.
  13. In the Completing the New Delegation Wizard page, click Finish.
  14. The delegation is shown in the DNS Manager console.
  15. For proper delegation, the Name Server records should also be added to Citrix ADC. (source = Citrix CTX241493 Citrix Response on DNS Flag Day)
    1. On the GSLB Citrix ADC appliances, expand Traffic Management, expand DNS, expand Records, and click Name Server Records.
    2. On the right, click Add.
    3. In the Domain Name field, enter the name of the delegated DNS name (e.g. gateway.corp.com).
    4. In the Name Server field, leave it set to –<< New >>–, and enter one of the FQDNs for your GSLB ADNS services. This is one of the glue records you created earlier.
    5. Click Create.
    6. Add another Name Server Record for the same domain name. But this time, enter the second GSLB ADNS FQDN. Repeat this process until all GSLB ADNS FQDNs are specified.

  16. Also add an SOA record for the delegation. If you are delegating individual records, then you will need an SOA for each record. If you are delegating a subzone, you only need an SOA record for the subzone.
    1. On the left, in the menu, go to Traffic Management > DNS > Records > SOA Records.
    2. On the right, click Add.
    3. In the Domain Name field, enter the FQDN that you delegated to NetScaler. This can be an individual record, or a sub-zone.
    4. In the Origin Server field, leave it set to –<< New >> — and then enter the FQDN that resolves to one of your ADNS listeners. It doesn’t matter which one you enter.
    5. In the Contact field, enter an email address that is publicly viewable. Replace the @ symbol with a period.
    6. Click Create.
    7. Repeat this on the other ADCs that are participating in GSLB for this delegated DNS name.
  17. If you run nslookup against your Microsoft DNS server, it will respond with Non-authoritative answer. That’s because it got the response from Citrix ADC, and not from the original DNS server that you send the request to.

Delegate a Sub-zone

  1. Run DNS Manager.
  2. First, create Host Records pointing to the ADNS services running on the Citrix ADC pairs in each data center. These are sometimes called glue records.

    1. The first Host record is gslb1 (or similar), and should point to the ADNS service (Public IP) on one of the Citrix ADC appliances.
    2. The second Host record is gslb2, and should point to the ADNS Service (public IP) on the other Citrix ADC appliance.
  3. Right-click the parent DNS zone, and click New Delegation.
  4. In the Welcome to the New Delegation Wizard page, click Next.
  5. In the Delegated Domain Name page, enter the left part of the DNS sub-zone that you are delegating (e.g. gslb for gslb.corp.com). Click Next.
  6. In the Name Servers page, click Add.
  7. This is where you specify gslb1.corp.com and gslb2.corp.com. Enter gslb1.corp.com, and click Resolve. Then click OK. If you see a message about the server not being authoritative for the zone, ignore the message. Note: you only add one name server at a time.
  8. Then click Add to add the other GSLB ADNS server.
  9. Once both ADNS servers are added to the list, click Next.
  10. In the Completing the New Delegation Wizard page, click Finish.
  11. The sub-zone delegation is shown in the DNS Manager console.
  12. For proper delegation, the Name Server records should also be added to Citrix ADC. (source = Citrix CTX241493 Citrix Response on DNS Flag Day)
    1. On the GSLB Citrix ADC appliances, expand Traffic Management, expand DNS, expand Records, and click Name Server Records.
    2. On the right, click Add.
    3. In the Domain Name field, enter the name of the delegated sub-domain (e.g. gslb.corp.com).
    4. In the Name Server field, leave it set to –<< New >>–, and enter one of the FQDNs for your GSLB ADNS services. This is one of the glue records you created earlier.
    5. Click Create.
    6. Add another Name Server Record for the same domain name. But this time, enter the second GSLB ADNS FQDN.

    7. Repeat this process until all GSLB ADNS FQDNs are specified.
  13. Also add an SOA record for the delegation. If you are delegating individual records, then you will need an SOA for each record. If you are delegating a subzone, you only need an SOA record for the subzone.
    1. On the left, in the menu, go to Traffic Management > DNS > Records > SOA Records.
    2. On the right, click Add.
    3. In the Domain Name field, enter the FQDN that you delegated to NetScaler. This can be an individual record, or a sub-zone.
    4. In the Origin Server field, leave it set to –<< New >> — and then enter the FQDN that resolves to one of your ADNS listeners. It doesn’t matter which one you enter.
    5. In the Contact field, enter an email address that is publicly viewable. Replace the @ symbol with a period.
    6. Click Create.
    7. Repeat this on the other ADCs that are participating in GSLB for this delegated DNS name.

Each GSLB-enabled DNS name must be CNAME’d to GSLB:

  1. In Citrix ADC, go to Traffic Management > GSLB > Virtual Servers, and edit your GSLB Virtual Server.
  2. On the left, click in the GSLB Virtual Server Domain Binding section.
  3. Click Add Binding.
  4. Add a domain binding for the CNAME’d DNS name. For example, if the original DNS name is gateway.corp.com, then enter gateway.gslb.corp.com. gslb.corp.com matches the sub-zone that you delegated to Citrix ADC. Click OK.
  5. Repeat the Domain Binding on the other Citrix ADC appliances.
  6. In DNS Manager, if you currently have a host record for the service that you are delegating to GSLB (gateway.corp.com), delete it.
  7. Right-click the DNS zone, and click New Alias (CNAME).
  8. In the Alias name field, enter the left part of the original DNS name. For gateway.corp.com, enter gateway.
  9. In the Fully qualified domain name (FQDN) for target host field, enter the CNAME’d DNS name that is delegated to Citrix ADC. For example, if you delegated gslb.corp.com to Citrix ADC, then enter gateway.gslb.corp.com. The GSLB Virtual Server must be configured to match this longer DNS name.
  10. Click OK.
  11. If you run nslookup for the delegated DNS name, it will first CNAME to the longer name, and then respond with the IP address returned by Citrix ADC GSLB.
  12. You can repeat these steps to delegate (CNAME) additional DNS names to Citrix ADC GSLB.

RADIUS Load Balancing – NetScaler 12

Last Modified: Apr 1, 2020 @ 6:41 am

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Change Log

  • 2018 Feb 17 – in RADIUS Monitor section, added Microsoft Network Policy Server Ping User-Name. (Source = Stefano Losego in the comments)
  • 2017 Dec 25 – updated entire article for 12.0 build 56. Monitor section has new build 56 instructions.

RADIUS Load Balancing Overview

One method of two-factor authentication to NetScaler Gateway is the RADIUS protocol with a two-factor authentication product (tokens) that has RADIUS enabled.

RADIUS Clients and Source IP – On your RADIUS servers, you’ll need to add the NetScaler appliances as RADIUS Clients. When NetScaler uses a local (same appliance) load balanced Virtual Server for RADIUS authentication, the traffic is sourced from the NetScaler SNIP (Subnet IP). When NetScaler uses a direct connection to a RADIUS Server without going through a load balancing Virtual Server, or uses a remote (different appliance) Load Balancing Virtual Server, the traffic is sourced from the NetScaler NSIP (NetScaler IP). Use the correct IP(s) when adding the NetScaler appliances as RADIUS Clients. And adjust firewall rules accordingly.

  • For High Availability pairs, if you locally load balance RADIUS, then you only need to add the SNIP as a RADIUS Client, since the SNIP floats between the two appliances. However, if you are not locally load balancing RADIUS, then you’ll need to add the NSIP of both appliances as RADIUS Clients. Use the same RADIUS Secret for both appliances.

RADIUS Monitor and Static Credentials – When load balancing RADIUS, you’ll want a monitor that verifies that the RADIUS server is functional. The RADIUS monitor will login to the RADIUS server and look for a response. The credentials in the load balancing monitor must have a static password.

  • If you don’t mind failed login attempts in your RADIUS logs, you can specify fake credentials in your load balancing monitor. The monitor would be configured to expect a login failure response, which means that at least a RADIUS service is responding to the monitor. Not as accurate as a successful login response, but better than ping.
  • The only other monitoring option is Ping. No credentials needed for this option. Adjust the firewall to allow ping to the RADIUS servers.

Active/passive load balancing – If you have RADIUS Servers in multiple datacenters, you can create multiple load balancing Virtual Servers, and cascade them so that the local RADIUS Servers are used first, and if they’re not available, then the Virtual Server fails over to RADIUS Servers in remote datacenters.

RADIUS Monitor

The RADIUS Monitor attempts to successfully log into the RADIUS server. For RSA, create an account on RSA with the following parameters as mentioned by Jonathan Pitre:

  • Setup a user with a fixed passcode in your RSA console.
  • Ensure you login with that user at least once to the RSA console because you’ll be asked to change it the first time.
  • There is no need to assign a token to your monitor user as long as you are using a fixed passcode. You don’t want to waste a token on a user just for monitoring.

Henny Louwers – Configure RSA RADIUS monitoring on NetScaler.

12.0 build 56 and newer

Monitor instructions changed in 12.0 build 56 and newer. If your build is older than build 56, then jump to the older Monitor instructions.

  1. In the NetScaler Configuration Utility, on the left, under Traffic Management > Load Balancing, click Monitors.
  2. On the right, click Add.
  3. Name the monitor RSA or similar.
  4. In the Type field, click where it says Click to select.
  5. Scroll down and click the circle next to RADIUS.
  6. Scroll up and click the blue Select button.
  7. In the Basic Parameters section, you might have to increase the Response Time-out to 4.
  8. In the Basic Parameters section, do the following:
    1. Enter valid RADIUS credentials. Make sure these credentials do not change or expire. For RSA, in the Password field, enter the fixed passcode.
    2. Enter the RADIUS key (secret) configured on the RADIUS server for the NetScaler as RADIUS client.
    3. For Response Codes, add both 2 and 3. 2 means success, while 3 indicates some kind of failure. Either result means that the RADIUS server is responding, and thus is probably functional. But 2 is the ideal response.
  9. Scroll down and click Create.

    add lb monitor RSA RADIUS -respCode 2-3 -userName ctxsvc -password Passw0rd -radKey Passw0rd -resptimeout 4
  10. Jump to the Servers section.

12.0 older than build 56

  1. In the NetScaler Configuration Utility, on the left, under Traffic Management > Load Balancing, click Monitors.
  2. On the right, click Add.
  3. Name the monitor RSA or similar.
  4. Change the Type drop-down to RADIUS.
  5. On the Standard Parameters tab, you might have to increase the Response Time-out to 4.
  6. On the Special Parameters tab, do the following:
    1. Enter valid RADIUS credentials. Make sure these credentials do not change or expire. For RSA, in the Password field, enter the fixed passcode.
    2. Also enter the RADIUS key (secret) configured on the RADIUS server for the NetScaler as RADIUS client.
    3. For Response Codes, add both 2 and 3. 2 means success, while 3 indicates some kind of failure. Either result means that the RADIUS server is responding, and thus is probably functional. But 2 is the ideal response.
  7. Click Create when done.

    add lb monitor RSA RADIUS -respCode 2-3 -userName ctxsvc -password Passw0rd -radKey Passw0rd -resptimeout 4

Servers

  1. On the left, expand Traffic Management, expand Load Balancing, and click Servers.
  2. On the right, click Add.
  3. Enter a descriptive server name; usually it matches the actual server name.
  4. Enter the IP address of the RADIUS server.
  5. Enter comments to describe the server. Click Create.

    add server RSA01 10.2.2.42
add server RSA02 10.2.2.43
  6. Continue adding RADIUS servers.

Service Groups

  1. On the left, expand Traffic Management, expand Load Balancing, and click Service Groups.
  2. On the right, click Add.
  3. You will create one Service Group per datacenter. Enter a name reflecting the name of the datacenter.
  4. Change the Protocol to RADIUS.
  5. Scroll down, and click OK, to close the Basic Settings section.
  6. On the left, in the Service Group Members section, click where it says No Service Group Member.

    1. If you did not create server objects, then enter the IP address of a RADIUS Server in this datacenter. If you previously created a server object, then change the selection to Server Based, and select the server object(s).
    2. In the Port field, enter 1812 (RADIUS).
    3. Click Create.
  7. Click OK when done adding members.
  8. On the right, in the Advanced Settings column, click Monitors.

    1. On the left, in the Monitors section, click where it says No Service Group to Monitor Binding.
    2. In the Select Monitor field, click where it says Click to select.
    3. Click the circle next to your new RADIUS monitor. It might be on page 2.
      • You must click the circle exactly (no room for error). If you click outside the circle, then the monitor will be opened for editing. If this happens, click Close to return to the selection screen.
    4. At the top of the window, click the blue Select button.
    5. Click Bind.
  9. To verify the members are up, click in the Service Group Members section.

    1. Right-click a member, and click Monitor Details.
    2. It should say Radius response code 2 (or 3) received. Click Close twice.
  10. Scroll down, and click Done to finish creating the Service Group.

    add serviceGroup svcgrp-RSA RADIUS
bind serviceGroup svcgrp-RSA RSA01 1812
bind serviceGroup svcgrp-RSA RSA02 1812
bind serviceGroup svcgrp-RSA -monitorName RSA
  11. Add additional service groups for RADIUS servers in each data center.

Virtual Server

  1. On the left, expand Traffic Management, expand Load Balancing, and click Virtual Servers.
  2. On the right, click Add.
  3. In the Basic Settings section, do the following:
    1. Name it lbvip-RADIUS-HQ or similar. You will create one Virtual Server per datacenter so include the datacenter name.
    2. Change the Protocol drop-down to RADIUS.
    3. Enter a Virtual IP. This VIP cannot conflict with any other IP + Port already being used. You can use an existing VIP if the VIP is not already listening on UDP 1812.
    4. Enter 1812 as the Port.
  4. Click OK to close the Basic Settings section.
  5. In the Services and Service Groups section, click where it says No Load Balancing Virtual Server ServiceGroup Binding.

    1. Click where it says Click to select.
    2. Click the circle next to a previously created Service Group. It might be on Page 2.
      • You must click the circle exactly (no room for error). If you click outside the circle, then the Service Group will be opened for editing. If this happens, click the x on the top right, or click Done on the bottom, to return to the selection screen.
    3. At the top of the window, click the blue Select button.
    4. Click Bind.
  6. Click Continue.
  7. On the right, in the Advanced Settings section, click Method.
  8. On the left, in the Method section, do the following:
    1. Change the Load Balancing Method to TOKEN.
    2. In the Expression box, enter CLIENT.UDP.RADIUS.USERNAME.
  9. Click OK to close the Method section.
  10. On the right, in the Advanced Settings section, click Persistence.
  11. On the left, in the Persistence section, do the following:
    1. Change Persistence to RULE. Note: 12.0 build 56 and newer is slightly different than older builds.
    2. In the Expression box, enter CLIENT.UDP.RADIUS.USERNAME.
  12. Click OK to close the Persistence section.
  13. Scroll down and click Done to finish creating the Virtual Server.
  14. If you are configuring this RADIUS Load Balancer for more than just NetScaler Gateway, you can add another Load Balancer on port 1813 for RADIUS Accounting. Then you need a Persistency Group to tie the two load balancers together. See Configuring RADIUS Load Balancing with Persistence at Citrix Docs. 
    add lb vserver lbvip-RSA RADIUS 10.2.2.210 1812 -persistenceType RULE -lbMethod TOKEN -rule CLIENT.UDP.RADIUS.USERNAME
bind lb vserver lbvip-RSA svcgrp-RSA
  15. The new Virtual Server should show as Up. If not, click the Refresh icon on the top right of the screen (not the browser refresh).

Active/Passive Load Balancing

  1. Create additional Virtual Servers for each datacenter.

    1. These additional Virtual Servers do not need a VIP. so change the IP Address Type to Non Addressable. Only the first Virtual Server will be directly accessible.

      add lb vserver lbvip-RSA-Backup RADIUS 0.0.0.0 0 -persistenceType NONE -cltTimeout 120
    2. Notice that the additional datacenter Virtual Servers have an IP Address of 0.0.0.0 and port of 0.
  2. After you are done creating a Virtual Server for each datacenter, right-click the primary datacenter’s Virtual Server, and click Edit.
  3. On the right, in the Advanced Settings column, click Protection.
  4. On the left, in the Protection section, change the Backup Virtual Server to one of the other datacenter Virtual Servers. If all of the services in this datacenter are DOWN, the backup Virtual Server will be used instead. You can cascade multiple Virtual Servers using this method. Click OK and Done.

    set lb vserver lbvip-RSA -backupVServer lbvip-RSA-Backup
  5. You may now use this Virtual IP in your RADIUS authentication policies for NetScaler Gateway or NetScaler management login.

CLI Commands

Here is a list of CLI Commands for RADIUS load balancing.

# Load Balancing Global Parameters
# --------------------------------
enable ns mode FR L3 Edge USNIP PMTUD ULFD
set ns tcpParam -WS ENABLED -SACK ENABLED


# Monitors
# --------
add lb monitor RSA RADIUS -respCode 2-3 -userName rsamon -password Passw0rd -encrypted -encryptmethod ENCMTHD_3 -radKey Passw0rd -encrypted -encryptmethod ENCMTHD_3 -LRTM DISABLED -resptimeout 4


# Servers
# -------
add server RSA01 10.2.2.42

add server RSA02 10.2.2.43


# Service Groups
# --------------
add serviceGroup svcgrp-RSA-RADIUS-DR RADIUS -maxClient 0 -maxReq 0 -cip DISABLED -usip NO -useproxyport NO -cltTimeout 120 -svrTimeout 120 -CKA NO -TCPB NO -CMP NO
bind serviceGroup svcgrp-RSA-RADIUS-DR RSA01 1812
bind serviceGroup svcgrp-RSA-RADIUS-DR -monitorName RSA

add serviceGroup svcgrp-RSA-RADIUS-HQ RADIUS -maxClient 0 -maxReq 0 -cip DISABLED -usip NO -useproxyport NO -cltTimeout 120 -svrTimeout 120 -CKA NO -TCPB NO -CMP NO
bind serviceGroup svcgrp-RSA-RADIUS-HQ RSA02 1812
bind serviceGroup svcgrp-RSA-RADIUS-HQ -monitorName RSA


# Load Balancing Virtual Servers
# ------------------------------
add lb vserver lbvip-RADIUS-DR RADIUS 0.0.0.0 0 -persistenceType NONE -cltTimeout 120
bind lb vserver lbvip-RADIUS-DR svcgrp-RSA-RADIUS-DR

add lb vserver "lbvip-RADIUS HQ" RADIUS 10.2.5.70 1812 -persistenceType RULE -lbMethod TOKEN -rule CLIENT.UDP.RADIUS.USERNAME -cltTimeout 120 -backupVServer lbvip-RADIUS-DR
bind lb vserver "lbvip-RADIUS HQ" svcgrp-RSA-RADIUS-HQ

Domain Controller (LDAPS) Load Balancing – Citrix ADC

Last Modified: Apr 12, 2023 @ 4:29 am

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💡 = Recently Updated

Changelog

  • 2017 Dec 25 – updated entire article for 12.0 build 56. Monitor section has new build 56 instructions.

Overview

If you plan to use LDAP (Active Directory) for Citrix Gateway, or Citrix ADC management authentication, then load balance the Domain Controllers that are used for authentication. A single LDAP Policy/Server points to the load balanced VIP.

Premature lockout – An alternative to load balancing is to bind multiple LDAP Policies, with each Policy pointing to a single Domain Controller in the same domain. However, Citrix ADC will try each authentication policy until it finds one that works. If the user enters a wrong password, and if you have three authentication policies pointing to different Domain Controllers in the same domain, then three different failure attempts will be recorded, thus causing premature account lockout. Use Load Balancing to avoid this behavior.

LDAPS and certificates – This page details LDAPS, aka Secure LDAP. This protocol requires certificates to be installed on the Domain Controllers. When a user’s password expires, Active Directory does not allow password changes over clear text LDAP, so LDAPS must be used instead. Make sure you have certificates installed on your Domain Controllers. The easiest way to accomplish that is to deploy a Microsoft Certificate Authority in Enterprise Mode, which allows the Domain Controllers to request certificates automatically.

Monitor -An ldaps monitor can be used to verify that the Domain Controller is functional.

  • The ldaps monitor will login as an account, perform an LDAP query, and look for a successful response. The ldaps monitor uses a service account to login. Make sure the service account’s password does not expire. Domain User permissions are sufficient.
  • Since this monitor is a Perl script, it uses NSIP as the source IP. You can use RNAT to override this as described in Configure to source Citrix ADC FreeBSD data traffic from a SNIP address at Citrix Docs.

Multiple datacenters – If you have Domain Controllers in multiple datacenters, you can create multiple load balancing Virtual Servers, and cascade them so that the local Domain Controllers are used first, and if they’re not available, then the Virtual Server fails over to Domain Controllers in remote datacenters.

Load Balancing Protocol – The Load Balancing Virtual Server for LDAPS can be TCP protocol or SSL_TCP protocol:

  • TCP – If the protocol is TCP, then SSL-encrypted LDAP traffic is not terminated on the Citrix ADC, and is simply forwarded to the LDAP servers. If your LDAP client (e.g. Linux machine) needs to verify the LDAP server certificate, then this Load Balancing configuration will not work, since each back-end LDAP server will have a different certificate.
  • SSL_TCP – If your Load Balancing Virtual Server is protocol SSL_TCP, then a certificate must be installed on the Citrix ADC and bound to the Load Balancing Virtual Server. SSL is terminated at the Citrix ADC and re-encrypted before sending it to the destination Domain Controller. The primary benefit of Citrix ADC SSL termination is that your LDAP clients can verify the Virtual Server SSL certificate.

Source IP – When Citrix ADC uses a local (same appliance) load balanced Virtual Server for LDAPS authentication, the traffic is sourced from the Citrix ADC SNIP (Subnet IP). When Citrix ADC uses a direct connection to a Domain Controller without going through a local Load Balancing Virtual Server, or if Citrix ADC uses a remote (different appliance) Load Balancing VIP, then the traffic is sourced from the Citrix ADC NSIP (NetScaler IP). Adjust firewall rules accordingly.

LDAPS Monitor

Note: Perl (scriptable) monitor uses NSIP as the source IP. You can use RNAT to override this as described in Configure to source Citrix ADC FreeBSD data traffic from a SNIP address at Citrix Docs.

12.0 build 56 and newer

Instructions for creating the monitor changed in 12.0 build 56 and newer. If your build is older, skip to the older instructions.

  1. In the Citrix ADC Configuration Utility, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name the monitor ldaps-Corp or similar. The ldaps monitor logs into Active Directory, performs an LDAP query, and looks for a successful response. The monitor configuration has domain-specific information, so if you have multiple Active Directory domains, then you will need a separate ldaps monitor for each domain. Include the domain name in the monitor name.
  4. In the Type field, click where it says Click to select.
  5. Scroll down and click the circle next to LDAP.
  6. At the top of the window, click the blue Select button.
  7. Scroll down the Basic  Parameters section, and check the box next to Secure. This checkbox instructs the monitor to connect to the Domain Controllers using LDAPS instead of LDAP.
  8. Scroll back up, and configure the following:
    • In the Base DN field, enter your domain name in LDAP format (e.g. dc=company,dc=com).
    • In the Bind DN field, enter the UPN login (e.g. ctxsvc@company.com) of a service account in the domain that can browse all objects. Any normal Domain User should be sufficient. Just make sure the password doesn’t expire.
    • In the Filter field, enter cn=builtin. This limits the search results so it’s not returning the entire domain.
    • In the Password field (higher in the list), enter the password for the service account. Make sure there is no semicolon in the password or the Perl script will be unable to parse the parameters.
  9. Scroll down and click Create.

    add lb monitor LDAP-Corp LDAP -scriptName nsldap.pl -dispatcherIP 127.0.0.1 -dispatcherPort 3013 -password Passw0rd -secure YES -baseDN "dc=corp,dc=local" -bindDN "corp\\ctxsvc" -filter cn=builtin
  10. If you have multiple domains, then create additional monitors: one for each domain.
  11. Jump to the Servers section.

12.0 older than build 56

  1. In the Citrix ADC Configuration Utility, expand Traffic Management, expand Load Balancing, and click Monitors.
  2. On the right, click Add.
  3. Name the monitor ldaps-Corp or similar. The ldaps monitor logs into Active Directory, performs an LDAP query, and looks for a successful response. The monitor configuration has domain-specific information, so if you have multiple Active Directory domains, then you will need a separate ldaps monitor for each domain. Include the domain name in the monitor name.
  4. Change the Type drop-down to LDAP.
  5. Scroll down the Standard Parameters tab, and check the box next to Secure. This checkbox instructs the monitor to connect to the Domain Controllers using LDAPS instead of LDAP.
  6. Scroll back up, and switch to the Special Parameters tab.
  7. Configure the following on the Special Parameters tab:
    • Use the Script Name drop-down list to select the nsldap.pl file.
    • In the Base DN field, enter your domain name in LDAP format (e.g. dc=company,dc=com).
    • In the Bind DN field, enter the UPN login (e.g. ctxsvc@company.com) of a service account in the domain that can browse all objects. Any normal Domain User should be sufficient. Just make sure the password doesn’t expire.
    • In the Filter field, enter cn=builtin. This limits the search results so it’s not returning the entire domain.
    • In the Password field, enter the password for the service account. Make sure there is no semicolon in the password or the script will be unable to parse the parameters.
  8. Click Create.

    add lb monitor LDAP-Corp LDAP -scriptName nsldap.pl -dispatcherIP 127.0.0.1 -dispatcherPort 3013 -password Passw0rd -secure YES -baseDN "dc=corp,dc=local" -bindDN "corp\\ctxsvc" -filter cn=builtin
  9. If you have multiple domains, then create additional monitors: one for each domain.

Servers

  1. On the left, expand Traffic Management, expand Load Balancing, and click Servers.
  2. On the right, click Add.
  3. Enter the following in the Create Server section.
    • In the Name field, enter a descriptive server name. Usually it matches the actual server name.
    • In the IPAddress field, enter the IP address of the server. Note: you can alternatively change the selection to Domain Name and enter a FQDN. This requires the Citrix ADC the be able to resolve the FQDN.
    • Enter comments to describe the server.
  4. Click Create.

    add server AD01 10.2.2.11
add server AD02 10.2.2.12
  5. Continue adding Domain Controllers. You usually want at least two per domain.

Service Groups

  1. On the left, expand Traffic Management, expand Load Balancing, and click Service Groups.
  2. On the right, click Add
    .
  3. In the Basic Settings section, do the following:
    • In the Name field: You will create one Service Group per datacenter. Enter a name reflecting the name of the data center. Also, you will create a set of service groups per Active Directory domain, so include the domain name.
    • Change the Protocol drop-down to SSL_TCP.
  4. Scroll down, and click OK to close the Basic Settings section.

  5. On the left, in the Service Group Members section, click where it says No Service Group Member.

    1. If you did not create server objects, then leave the selection set to IP Based, and enter the IP address of a Domain Controller in this datacenter.
    2. If you previously created server objects, then change the selection to Server Based, and select the server objects.
    3. In the Port field, enter 636 (LDAPS). This assumes the Domain Controllers have certificates installed.
    4. Click Create.
  6. Click OK to close the Service Group Members section.
  7. On the right, in the Advanced Settings column, click Monitors.
  8. On the left, in the Monitors section, click where it says No Service Group to Monitor Binding.

    1. In the Select Monitor field, click where it says Click to select.
    2. Click the circle next to the LDAPS monitor you created earlier. The monitor might be on Page 2.
      1. The circle must be clicked exactly (no room for error). If you click outside the circle, then the monitor will open for editing. If this happens, click Close to return to the selection screen.
    3. At the top of the window, click the blue Select button.
    4. Click Bind.
  9. To verify the members are up, click in the Service Group Members section.

    1. Right-click a member, and click Monitor Details.
    2. The Last Response field should say Success – Probe succeeded. Click Close. It’s too bad you can’t edit the monitor from here.

      • If the monitor doesn’t work, use ldp.exe to verify the Domain Controller certificate.
  10. Click Close and Done to finish creating the Service Group.

    add serviceGroup svcgrp-LDAP-Corp SSL_TCP
bind serviceGroup svcgrp-LDAP-Corp AD01 636
bind serviceGroup svcgrp-LDAP-Corp AD02 636
bind serviceGroup svcgrp-LDAP-Corp -monitorName LDAP-Corp
  11. Add additional service groups for Domain Controllers for each domain in each data center.

Load Balancing Virtual Server

  1. Create or import a certificate that matches the FQDN that resolves to the new Load Balancing VIP for LDAPS.
  2. On the left, expand Traffic Management, expand Load Balancing, and click Virtual Servers.
  3. On the right, click Add.
  4. In the Basic Settings section, do the following:
    • Name it LDAPS-Corp-HQ-LB or similar. You will create one Virtual Server per datacenter, so include the datacenter name. Also, each domain has a separate set of Virtual Servers, so include the domain name.
    • Change the Protocol drop-down to SSL_TCP.
    • Enter a Virtual IP. This VIP cannot conflict with any other IP + Port already being used. You can use an existing VIP that is not already listening on TCP 636.
    • Enter 636 as the Port.
  5. Click OK to close the Basic Settings section.
  6. On the left, in the Service Group section, click where it says No Load Balancing Virtual Server ServiceGroup Binding.

    1. Click where it says Click to select.
    2. Click the circle next to a previously created Service Group. It might be on page 2.
      1. The circle must be clicked exactly (no room for error). If you click outside the circle, then the Service Group will open for editing. If this happens, click the x on the top right, or the Done button on the bottom, to return to the selection screen.
    3. At top of the screen, click the blue Select button.
    4. Click Bind.
  7. Click Continue to close the Services and Service Groups section.
  8. On the left, in the Certificates section, click where it says No Server Certificate.

    1. Click where it says Click to select.
    2. Click the circle next to a certificate that matches the FQDN that resolves to this VIP. It might be on page 2.
    3. At the top of the window, click the blue Select button.
    4. Click Bind.
  9. Click Continue to close the Certificates section.

    add lb vserver lbvip-LDAP-Corp SSL_TCP 10.2.2.210 636 -persistenceType NONE -cltTimeout 9000

bind lb vserver lbvip-LDAP-Corp svcgrp-LDAP-Corp
  10. There’s no need to configure Persistence for LDAP.
  11. If you haven’t enabled the Default SSL Profile, then perform other normal SSL configuration including: disable SSLv3, and bind an A+ Cipher Group.
  12. Click Done to finish creating the Virtual Server.
  13. The new Virtual Server should show as UP.

Backup Virtual Server

You can optionally configure this Load Balancing Virtual Server to failover to a different Load Balancing Virtual Server. This allows you to load balance Domain Controllers in this datacenter, and if down, failover to the other datacenter.

  1. Create additional Load Balancing Virtual Servers for each datacenter.
    • These additional Virtual Servers do not need a VIP, so change the IP Address Type to Non Addressable. Only the first Virtual Server will be directly accessible.

      add lb vserver lbvip-LDAP-Corp-Backup SSL_TCP 0.0.0.0 0
    • Notice that the additional datacenter Virtual Servers show up with an IP Address of 0.0.0.0 and port of 0.
  2. After you are done creating a Virtual Server for each datacenter, right-click the primary datacenter’s Virtual Server, and click Edit.
  3. On the right, in the Advanced Settings column, click Protection.
  4. On the left, in the Protection section, change the Backup Virtual Server to one of the other datacenter Virtual Servers. If all of the services in this datacenter are DOWN, the backup Virtual Server will be used instead. You can cascade multiple Virtual Servers using this method. Click OK and Done.

    set lb vserver lbvip-LDAP-Corp -backupVServer lbvip-LDAP-Corp-Backup

CLI Commands

Here is a list of CLI Commands for Domain Controller Load Balancing.

# SSL Global Parameters
# ---------------------
set ssl parameter -denySSLReneg NONSECURE

# Certs
# -----
add ssl certKey WildcardCorpCom -cert WildcardCorpCom.pfx -key WildcardCorpCom.pfx -inform PFX -passcrypt "Passw0rd"


# Load Balancing Global Parameters
# --------------------------------
enable ns mode FR L3 Edge USNIP PMTUD ULFD
set lb parameter -sessionsThreshold 150000
set ns param -cookieversion 1 -timezone "GMT-06:00-CST-America/Chicago"
set dns parameter -dns64Timeout 1000
set ns tcpParam -WS ENABLED -SACK ENABLED
set ns httpParam -dropInvalReqs ON
set ns tcpbufParam -memLimit 390

# Monitors
# --------
add lb monitor ldaps-Corp LDAP -scriptName nsldap.pl -dispatcherIP 127.0.0.1 -dispatcherPort 3013 -password Passw0rd -encrypted -encryptmethod ENCMTHD_3 -LRTM DISABLED -secure YES -baseDN "dc=corp,dc=local" -bindDN admin@corp.local -filter cn=builtin


# Servers
# -------
add server AD01 10.2.2.11

add server AD03 10.2.2.115


# Service Groups
# --------------
add serviceGroup svcgrp-LDAPS-Corp-HQ SSL_TCP -maxClient 0 -maxReq 0 -cip DISABLED -usip NO -useproxyport YES -cltTimeout 9000 -svrTimeout 9000 -CKA NO -TCPB NO -CMP NO
bind serviceGroup svcgrp-LDAPS-Corp-HQ AD01 636
bind serviceGroup svcgrp-LDAPS-Corp-HQ AD03 636
bind serviceGroup svcgrp-LDAPS-Corp-HQ -monitorName ldaps-Corp
set ssl serviceGroup svcgrp-LDAPS-Corp-HQ -sslProfile ns_default_ssl_profile_backend


# Load Balancing Virtual Servers
# ------------------------------
add lb vserver LDAPS-Corp-DR-LB SSL_TCP 0.0.0.0 0 -persistenceType NONE -cltTimeout 9000
bind lb vserver LDAPS-Corp-DR-LB svcgrp-LDAPS-Corp-HQ

add lb vserver LDAPS-Corp-HQ-LB SSL_TCP 10.2.5.220 636 -persistenceType NONE -cltTimeout 9000 -backupVServer LDAPS-Corp-DR-LB
bind lb vserver LDAPS-Corp-HQ-LB svcgrp-LDAPS-Corp-HQ


# SSL Virtual Servers
# -------------------
set ssl vserver LDAPS-Corp-DR-LB -sslProfile ns_default_ssl_profile_frontend
bind ssl vserver LDAPS-Corp-DR-LB -certkeyName WildcardCorpCom
bind ssl vserver LDAPS-Corp-DR-LB -eccCurveName P_256
bind ssl vserver LDAPS-Corp-DR-LB -eccCurveName P_384
bind ssl vserver LDAPS-Corp-DR-LB -eccCurveName P_224
bind ssl vserver LDAPS-Corp-DR-LB -eccCurveName P_521

set ssl vserver LDAPS-Corp-HQ-LB -sslProfile ns_default_ssl_profile_frontend
bind ssl vserver LDAPS-Corp-HQ-LB -certkeyName WildcardCorpCom
bind ssl vserver LDAPS-Corp-HQ-LB -eccCurveName P_256
bind ssl vserver LDAPS-Corp-HQ-LB -eccCurveName P_384
bind ssl vserver LDAPS-Corp-HQ-LB -eccCurveName P_224
bind ssl vserver LDAPS-Corp-HQ-LB -eccCurveName P_521

Next Steps

You may now use this Virtual IP in your Citrix Gateway LDAP authentication policies, or Citrix ADC management login.