Integrating and Troubleshooting Citrix Access Gateway

External Internal DMZ Basic Firewall and Port Rules AGEE Admin Remote End User VIP NSIP XenApp WI STA 443,80* (HTTP/TCP) NSIP DNS * Port 80 used for https redirect NSIP LDAP/ LDAPS SNIP or MIP 389/636 (TCP) 53 (UDP) 443,80 (TCP/HTTP) 3010, 3008,22 (TCP) 80, 8080, 443 (HTTP/TCP) 1494, 2598 (TCP)

External Remote End User LDAP WI Internal DMZ STA and XML / /636 SmartAccess Workflow EE returns EPA results to WI Session policy EPA check results returned to AGEE Web Interface sends credentials & EPA results to Citrix XML Service which validates them and returns user’s “smart access” application set to Web Interface. Web Interface generates “Smart Access” application set page and sends the web page back to user. Access Gateway passes credentials to Directory Service for validation. EPA ActiveX sends results back to AGEE On Pre-Authentication EPA success AGEE returns login page Post-AuthN AGEE Session policy EPA checks done with the existing EPA ActiveX Web Interface Authenticates credentials provided via custom SSO AGCitrixBasic Header AGEE Pre-AuthN EPA ActiveX download & client scan 1)AGEE does a HTTP redirect to the website configured in ‘-homepage’ option 2) Web Interface returns a 401 and AGEE detects that this is a Web Interface server. User supplies credentials to logon page. User accesses AGEE VPN Virtual Server 3) Access Gateway next performs pass- through SSO to Web Interface via a custom AGCitrixBasic HTTP Header 4) A SessionToken is also provided WI makes a XML callback to a preconfigured-on-WI AGEE VPN Virtual Server URL with the previously provided SessionToken to get the EPA Results XenApp

Deeper Look at Security Scans – Pre-Auth Redirect to /epa/epa.html EPA client sends a GET for /epaq which causes the Access Gateway to return a 200 OK response with a HTTP header called CSE If the security scan passes, the very next GET from the client will contain a value of 0 for the CSEC header. If the scan fails, the value will be 3. Example:

Web Interface then validates the credentials via a POST back to Access Gateway If that connection succeeds, the Access Gateway then returns a 200 OK containing all the Smart Access information needed by Web Interface. Example: Deeper Look Into Smart Access Client logs in to Access Gateway and is redirected to Web Interface During this redirection the client sends a request to /auth/agesso.aspx Web interface denies access and requests credentials. Access Gateway then sends another request to /auth/agesso.aspx but this time with an authentication header How Did I Do That ????

Decrypting a Network Trace In order to be able to analyze the data on the previous slide I had to run a network trace on the Access Gateway appliance. This can easily be done via GUI: Or via the command line: Once the network trace has run it will be placed under /var/nstrace/ *** important: since this is SSL traffic the trace has to start before any request is made *** Once the trace is downloaded to a workstation that has Wireshark installed, open Wireshark click on Edit and then Preferences. Select SSL under Protocols: Under RSA Key List you enter:,,, Once that is done the traffic will be decrypted and you will be able to analyze it.

What if private key is not available? How to create a HTTP debug virtual server:

What if private key is secured? If the private key was created with a passphrase, it can be decrypted via openssl:

External Remote End User XenApp WI InternalDMZ STA and XML / /2598 User clicks application icon. Request is sent to Web Interface. Web Interface contacts Citrix XML Service to determine least loaded XenApp server hosting application. XML Service returns XenApp IP address. Web Interface contacts STA to exchange XenApp IP address for ticket. Web Interface generates ICA file that includes Access Gateway FQDN and STA ticket. ICA file is sent back to client device. ICA Client sends ICA request to Access Gateway. Access Gateway contacts STA to validate ticket and exchange the ticket for the XenApp IP address. Access Gateway contacts XenApp to initiate ICA session. ICA session is established. Published Application Launch Process

XenApp Integration: Web Interface Site Type Specify the URL to the Virtual Server’s FQDN Web Interface must be able to resolve the FQDN Specify the URL to the Virtual Server’s FQDN Web Interface must be able to resolve the FQDN Web Interface XenApp Access Gateway

XenApp Integration: Web Interface DMZ Settings Set the DMZ Access Method to Gateway Direct Web Interface XenApp Access Gateway

Specify the Access Gateway Virtual Server’s FQDN as the Gateway Server XenApp Integration: Web Interface Gateway Settings Web Interface XenApp Access Gateway

Enter the STA server URL address XenApp Integration: Web Interface Gateway Settings Web Interface XenApp Access Gateway

URL to the Web Interface site e.g. HTTP(S)://wiserver/citrix/accessplatform ICA Proxy ON tells AGEE not to launch the Secure Access Client ICA Proxy ON enables SSO to WI Single Sign-On Domain defines the users domain name Embedded Web Interface display format Full or Compact Embedded Web Interface display format Full or Compact XenApp Integration: Session Profile Configuration

The STA Server ID and State are monitored by AGEE Multiple STA Servers can be defined for failover The STA Server ID and State are monitored by AGEE Multiple STA Servers can be defined for failover XenApp Integration: Defining STA Server Web Interface XenApp Access Gateway

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