ICA Proxy (StoreFront) – NetScaler Gateway 12 / Citrix Gateway 12.1

Last Modified: Oct 13, 2018 @ 10:21 am

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Overview

Here’s a high level overview of internal connectivity from client devices to Citrix Virtual Apps and Desktops (CVAD):

  1. HTTP connection to Citrix StoreFront:
    • Authentication to StoreFront
    • User interface that displays a list Citrix published icons
  2. ICA connection directly to a Citrix Virtual Delivery Agent (VDA)
    • ICA is a display protocol similar to RDP protocol

Citrix Gateway has an ICA Proxy feature that authenticates the user, proxies HTTP traffic to StoreFront, and then proxies ICA traffic to VDAs.

  • ICA Proxy is just one of the features that Citrix Gateway supports. Other Gateway features include: SSL VPN, Unified Gateway, RDP Proxy, PCoIP Proxy, etc.
  • ICA Proxy only exposes a single IP address to the user. All communication from all external Citrix clients to all internal StoreFront servers and all internal VDAs is proxied through the one IP address.
    • The “single IP address” feature is also sometimes useful internally, especially if there’s any Network Address Translation between internal subnets, or if the Citrix VDAs are protected behind an internal firewall.
  • Citrix Gateway supports many different authentication methods, including: LDAP, RADIUS, SAML, OpenID Connect, nFactor, Client Certificates (Smart Cards), etc.
    • Citrix Gateway has more authentication options than StoreFront. Sometimes Citrix Gateway is deployed in front of StoreFront just for the additional authentication options that Citrix Gateway provides.
  • Both HTTP and ICA are proxied through a single TLS-encrypted port 443. ICA Proxy decrypts the traffic and inspects it.
    • If the traffic is HTTP protocol, then ICA Proxy forwards it to Citrix StoreFront. The address of the StoreFront server is defined in a Session Policy/Profile on the Published Applications tab.
    • If the traffic is ICA protocol, then ICA Proxy uses a Secure Ticket Authority (STA) server to authenticate the connection, and then forwards the unencrypted ICA traffic to the VDA.
    • DTLS-encrypted (UDP) port 443 is also an option – UDP protocol for ICA traffic performs better than TCP on high latency links

There are two user interface options for connecting to Citrix Virtual Apps and Desktops (CVAD). Both user interface options rely on a connection to StoreFront. ICA Proxy is configured differently for each user interface.

  • Web Browser – Chrome, Safari, etc. connecting to the Receiver for Web website hosted on Citrix StoreFront.
  • Receiver Self-Service – native user interface built into Receiver / Workspace app that connects to an XML-based API hosted on Citrix StoreFront.
    • In all operating systems, Receiver Self-Service is the user interface that opens when you launch Receiver or Workspace app from the app launcher.
    • In Windows,¬†Receiver Self-Service is the user interface that you can open from the Receiver / Workspace app systray icon.
    • In Windows, Receiver Self-Service can download icons from StoreFront and put the icons on the client device’s app launcher (Start Menu and/or Desktop) without needing to actually open the Receiver Self-Service window.

Links:

Session Profiles

Partly based on Citrix Knowledgebase Article CTX139963 –¬†How to Configure NetScaler Gateway Session Policies for StoreFront

To create Session Profiles/Policies for ICA Proxy (StoreFront):

  1. On the left, expand NetScaler Gateway, expand Policies, and click Session.
  2. On the right, switch to the Session Profiles tab, and click Add.

    1. Name the first one Receiver Self Service or similar. This is for the Receiver Self-Service interface (not from a web browser).
    2. Switch to the Client Experience tab.
    3. On the Client Experience tab, check the Override Global box next to Clientless Access, and set it to Off. Scroll down.
    4. Check the Override Global box next to Plug-in Type, and set it to Java.
    5. Check the Override Global box next to Single Sign-on to Web Applications and enable it. Scroll up.

      • If you need two-factor authentication (RADIUS), the Session Policy for Receiver Self-Service needs to be adjusted to indicate which authentication field contains the Active Directory password. On the Client Experience tab is¬†Credential Index. This needs to be changed to SECONDARY. Only change this in the Receiver Self-Service profile; leave the session profile for Web Browsers set to PRIMARY.
    6. Scroll up and switch to the Security tab.
    7. Check the Override Global box next to Default Authorization Action, and set it to Allow.
    8. Switch to the Published Applications tab.
    9. Check the Override Global box next to ICA Proxy, and set it to ON.
    10. Check the Override Global box next to Web Interface Address, and enter the load balanced URL (FQDN) to the StoreFront servers. You can use an IP address instead of FQDN. Don’t add any path to the end of the URL.
    11. If you only have one domain, then check the Override Global box next to Single Sign-on Domain, and enter the name of your Active Directory domain. Enter the same domain name that’s configured in StoreFront’s¬†Configure Trusted Domains.

    12. For Account Services Address, enter the Base URL for StoreFront. NetScaler needs to be able to resolve this FQDN’s DNS name.
    13. Click Create.
  3. Right-click the just-added session profile, and click Add. This copies the settings from the existing profile into the new one.

    1. Change the name of the second Session Profile to Receiver For Web or similar.
    2. Switch to the Client Experience tab.
    3. On the Client Experience tab, Clientless Access should be set to Off. Scroll down.
    4. Plug-in Type should still be set to Java.
    5. Single Sign-on to Web Applications should be enabled.

      • If you need two-factor authentication, the session profile for Receiver for Web¬†needs Credential Index¬†set to PRIMARY.¬†Only the Receiver Self-Service policy needs SECONDARY¬†as detailed earlier.
    6. Scroll up and switch to the Security tab.
    7. The Default Authorization Action should still be Allow.
    8. Switch to the Published Applications tab.
    9. For the Web Interface Address field, add the path to your Receiver for Web site (e.g. /Citrix/StoreWeb).
    10. Everything else should be the same. If you only have one domain, then check the Override Global box next to Single Sign-on Domain and enter the name of your Active Directory domain. If you have multiple domains, then leave this field blank and ensure the LDAP authentication servers have userPrincipalName in the SSO Name Attribute field.
    11. Account Services Address is not needed in this profile but there’s no harm in leaving it.
    12. Click Create.
  4. On the right, switch to the Session Policies tab, and click Add.

    1. Name the Policy Receiver Self Service or similar.
    2. Change the Profile to Receiver Self Service.
    3. In the Expression box, type in the following expression:
      HTTP.REQ.HEADER("User-Agent").CONTAINS("CitrixReceiver")
    4. Then click Create.
  5. Right-click on the just-added Session Policy, and click Add.

    1. Change the name to Receiver For Web or similar.
    2. Change the Profile to Receiver For Web.
    3. In the Expression box, either type in the following, or use the Expression Editor. It’s the same as the Receiver Self-Service expression, except it¬†has .NOT on the end.
      HTTP.REQ.HEADER("User-Agent").CONTAINS("CitrixReceiver").NOT
    4. Click Create.

The CLI commands for these Session Policies/Profiles are shown below:

add vpn sessionAction "Receiver Self-Service" -transparentInterception OFF -defaultAuthorizationAction ALLOW -SSO ON -icaProxy ON -wihome "https://storefront.corp.com" -ntDomain Corp.local -clientlessVpnMode OFF -storefronturl "https://storefront.corp.com"

add vpn sessionAction "Receiver for Web" -transparentInterception OFF -defaultAuthorizationAction ALLOW -SSO ON -icaProxy ON -wihome "https://storefront.corp.com/Citrix/StoreWeb" -ntDomain Corp.local -clientlessVpnMode OFF

add vpn sessionPolicy "Receiver Self-Service" "HTTP.REQ.HEADER(\"User-Agent\").CONTAINS(\"CitrixReceiver\")" "Receiver Self-Service"

add vpn sessionPolicy "Receiver for Web" "HTTP.REQ.HEADER(\"User-Agent\").CONTAINS(\"CitrixReceiver\").NOT" "Receiver for Web"

NetScaler Gateway / Citrix Gateway Virtual Server

This section assumes LDAP authentication, with optional RADIUS for two-factor. Create the Authentication Policies before beginning this section.

  • You can configure StoreFrontAuth as an alternative to LDAP. StoreFrontAuth delegates authentication to StoreFront servers, instead of performing authentication on NetScaler.
  • For other forms of authentication, see the¬†NetScaler 12 / Citrix ADC 12.1 Authentication section in the NetScaler 12 / Citrix ADC 12.1 menu page.

To create the NetScaler Gateway Virtual Server for ICA Proxy and StoreFront:

  1. At Traffic Management > SSL > Certificates > Server Certificates, Create a Server Certificate for the NetScaler Gateway Virtual Server. The certificate must match the name users will enter to access the NetScaler Gateway.

    • For email discovery in Citrix Receiver / Workspace app, the certificate must have subject alternative names (SAN) for¬†discoverReceiver.email.suffix (use your email suffix domain name). If you have multiple email domains then you‚Äôll need a Subject Alternative Name for each suffix.
  2. Link the certificate to the Intermediate CA certificate. Do not link the Intermediate CA certificate to the Root CA certificate.
  3. On the left, right-click NetScaler Gateway, and click Enable Feature.
  4. On the left, expand NetScaler Gateway, and click Virtual Servers.
  5. On the right, click Add.
  6. Name it gateway.corp.com or similar.
  7. Enter a new VIP that will be exposed to the Internet (typically through NAT).
  8. Click More.

    1. If you don’t have enough NetScaler Gateway Universal licenses installed for all of your Gateway users, then check the box next to¬†ICA Only. This option disables SmartAccess and VPN features but¬†does not require any additional licenses. ¬†Note: most NetScaler ADC Editions come with built-in Gateway Universal Licenses.
    2. Note: it’s also possible to disable authentication on Gateway and make StoreFront do it instead as described in Citrix CTX200066 How to Log On to StoreFront When Authentication is Disabled on NetScaler Gateway VIP. However, it’s more secure to require Gateway to authenticate the users before the user can communicate with StoreFront.
    3. On the right, check the box next to DTLS.
      • DTLS enables¬†EDT¬†protocol,¬†UDP Audio, and¬†Framehawk.
      • EDT¬†requires UDP 443 on client side, and UDP 1494/2598 on the server side.
      • If this NetScaler Gateway is in Azure, then you might have to reduce the MTU/MSS. See EDT-Adaptive Transport with Azure Netscaler at Citrix Discussions.
    4. Click OK to close the Basic Settings section.
  9. In the Certificate section, click where it says No Server Certificate.

    1. In the Server Certificate Binding section, click where it says Click to select.
    2. Click the radio button next to a previously created certificate that matches the Citrix Gateway DNS name, and then click the blue Select button at the top of the window.
    3. Click Bind.
  10. Click Continue to close the Certificate section.
  11. In the¬†Basic Authentication¬†section, click the plus icon in the top right. Note: NetScaler Gateway 12 and Citrix Gateway 12.1 only seem to only support Basic Authentication policies, and not Advanced Authentication policies. For Advanced Authentication Policies, you’ll instead need to configure nFactor.

    1. Change the Choose Policy drop-down to LDAP,
    2. Leave the Choose Type drop-down set to  Primary, and click Continue.
    3. If you’ve already created an LDAP Policy, then click where it says¬†Click to select, and select the policy.

    4. If you used the Authentication Dashboard to create an LDAP Server, then you probably haven’t created the corresponding LDAP Policy yet. Click the plus icon (Add button) to create a new policy.

      1. Use the Server drop-down to select the previously created LDAP Server.
      2. Give the policy a name. The Policy name can match the Server name.
      3. In the Expression box, enter ns_true (a Basic or Classic expression), or select it from the Saved Policy Expressions drop-down. Click Create.
    5. Click Bind.
    6. Or for two-factor authentication, bind two Basic authentication policies to Primary and two Basic authentication polices to Secondary:
      • Primary = LDAP for Browsers (User-Agent does not contain CitrixReceiver)
      • Primary = RADIUS for Receiver Self-Service (User-Agent contains CitrixReceiver)
      • Secondary = RADIUS for Browsers (User-Agent does not contain CitrixReceiver)
      • Secondary = LDAP for Receiver Self-Service (User-Agent contains CitrixReceiver)
  12. Click Continue to close the Basic Authentication section.
  13. In the Advanced Authentication section, click Continue.
  14. Scroll down to the Profiles section, and click the pencil icon.
  15. In the TCP Profile drop-down, do one of the following:
    1. Follow the instructions at¬†Citrix¬†CTX232321¬†Recommended TCP Profile Settings for Full Tunnel VPN/ICAProxy from NetScaler Gateway 11.1 Onwards. In this case, there’s no need to change the TCP Profile.
    2. Or, select nstcp_default_XA_XD_profile, and click OK to close the Profiles section.
  16. To bind the Session Policies, scroll down to the Policies section, and click the plus icon near the top right.

    1. Select Session, select Request, and click Continue.
    2. Click where it says Click to select.
    3. Click the radio button next to one of the Receiver Session Policies, and click the blue Select at the top of the window. It doesn’t matter in which order you bind them.
    4. There’s no need to change the priority number. Click Bind.
  17. Repeat these steps to bind the second policy. In the Policies section, click the plus icon near the top right.

    1. Select Session, select Request, and click Continue.
    2. Click Add Binding.
    3. Click where it says Click to select.
    4. Click the radio button next to the other Receiver session policy, and click Select.
    5. There’s no need to change the priority number. Click Bind.
    6. The two policies are mutually exclusive so there’s no need to adjust priority. Click Close.
  18. To bind Secure Ticket Authorities (STAs), on the right, in the Advanced Settings section, click Published Applications.
  19. On the left, in the Published Applications section, click where it says No STA Server.

    1. Enter a Delivery Controller in the https://<Controller_FQDN> or http://<Controller_FQDN> format, depending on if SSL is enabled on the Delivery Controller or not. This must be a FQDN or IP address. Short names don’t work.
    2. Click Bind.
  20. To bind another Secure Ticket Authority server, on the left, in the Published Applications section, click where it says 1 STA Server.

    1. In the VPN Virtual Server STA Server Binding section, click Add Binding.
    2. Enter the URL for the second Controller, and click Bind.
    3. This view shows if the STAs are reachable or not. To refresh the view, close the STA Server Bindings list, and reopen it.
    4. The list of NetScaler Gateway Virtual Servers also shows you if the STAs (STA Status) are up or not.
    5. By default, STA server reachability is only checked every 2 minutes. You can change this at Traffic Management > Load Balancing > Monitors, and edit the sta and stasecure built-in monitors (source = CTX231916 NetScaler Takes 3-4 Minutes to Mark STA as DOWN)

  21. On the right, in the Advanced Settings column, click Portal Themes.
  22. On the left, in the Portal Theme section, change the drop-down to X1 or RfWebUI. You can also click the plus icon to create a theme. Note: many existing Portal Theme customizations are written for X1, but not for RfWebUI.
  23. Click OK to close the Portal Theme section.
  24. If you haven’t enabled the Default SSL Profile, then perform other normal SSL configuration including: disable SSLv3, bind an A+ Cipher Group, and enable Strict Transport Security.
  25. Click Done when done.
  26. Configure SSL Redirect for the NetScaler Gateway DNS name and VIP.
  27. Configure StoreFront to use NetScaler Gateway.

The CLI commands to create a NetScaler Gateway vServer for ICA Proxy are shown below:

add vpn vserver gateway.corp.com SSL 10.2.2.200 443 -icaOnly ON -dtls ON -tcpProfileName nstcp_default_XA_XD_profile
bind vpn vserver gateway.corp.com -policy "Receiver Self-Service" -priority 100
bind vpn vserver gateway.corp.com -policy "Receiver for Web" -priority 110
bind vpn vserver gateway.corp.com -policy Corp-Gateway -priority 100
bind vpn vserver gateway.corp.com -staServer "http://xdc01.corp.local"
bind vpn vserver gateway.corp.com -staServer "http://xdc02.corp.local"
bind vpn vserver gateway.corp.com -portaltheme RfWebUI

Verify SSL Settings

After you’ve created the NetScaler Gateway Virtual Server, run the following tests to verify SSL:

  1. Go to¬†https://www.ssllabs.com/ssltest/¬†and check the security settings of the website.¬†Citrix Blogs ‚ÄstScoring an A+ at SSLlabs.com with Citrix NetScaler ‚Äď Q2 2018 update.
  2. Citrix CTX200890 ‚ÄstError: “Failed with status 1110” When Launching Desktops or Apps Through NetScaler Gateway: You can use OpenSSL to verify the certificate. Run the command:¬†openssl s_client -connect gateway.corp.com:443.¬†Replace the FQDN with your FQDN. OpenSSL is installed on the NetScaler, or you can download and install it on any machine.

View ICA Connections

To view active ICA proxy sessions, click the NetScaler Gateway node on the left, and then click ICA Connections on the right.

show vpn icaconnection

To view historical ICA sessions, search your Syslog server for ICASTART and/or LOGIN.

Or, if you don’t have Syslog server configured, then search /var/log/ns.log¬†on the local appliance. Source =¬†CTX232581¬†How to View Active Users Sessions Connected to Specific NetScaler Gateway vServers.

Logoff is Successful

With newer versions of StoreFront and Citrix Gateway, when you logoff StoreFront 3.15+ that is proxied through Gateway, all you see is a white page with the text “Logoff is successful”.

Alternatively, you can redirect to the Gateway logon page by creating and binding a Responder policy: (source =¬†Storefront 3.15 “Logoff Is Successful” at Reddit)

  1. In the menu, go to AppExpert > Responder > Actions.
  2. Enable the Responder feature if it isn’t already enabled.
  3. On the right, click Add.
  4. In the Create Responder Action window:
    1. Give the Responder Action a name. The purpose of this Responder is to redirect to the Gateway logon page after StoreFront is logged off.
    2. Change the¬†Type drop-down to¬†Redirect. Note: it’s easy to miss this step.
    3. In the Expression box, you can enter "https://" + HTTP.REQ.HOSTNAME.HTTP_URL_SAFE or you can enter the actual https:// URL to the Gateway Virtual Server. The first option uses the Gateway FQDN originally entered by the user.
  5. Click Create.
  6. On the left, in the menu, click the Policies node under Responder.
  7. On the right, click Add.
  8. In the Create Responder Policy window:
    1. Give the Responder Policy a name.
    2. Change the Action drop-down to the name of the Responder Action you just created.
    3. In the Expression box enter HTTP.REQ.URL.CONTAINS("/cgi/logout")
  9. Click Create.
  10. In the menu, go to NetScaler Gateway > Virtual Servers.
  11. Edit your Gateway Virtual Server.
  12. Scroll down to the Policies section and click the plus icon.
  13. Change the Choose Policy drop-down to Responder and click Continue.
  14. In the Policy Binding section, click where it says Click to select.
  15. Click the radio button (circle) next to the Responder Policy you just created and then click the blue Select button at the top of the page.
  16. Click Bind.

Related Pages

5 thoughts on “ICA Proxy (StoreFront) – NetScaler Gateway 12 / Citrix Gateway 12.1”

  1. hi Carl question if i follow that storefront authentication guide, where via the wizard i configure the gateway vip i add the certificate and the storefront authentication method , do i need to create manually session profiles and session policies or they are created via that wizard???? . I did that wizard and i also checked default ssl profile enabled and ica only since i dont want vpn sesions via netscaler

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