Product Documentation

Sample Deployment with SSL Relay and the Web Interface

May 08, 2015

This deployment uses SSL Relay and the Web Interface to encrypt ICA and HTTP communication between the XenApp server and the web server. Encrypted communication between the web browser and the web server is by using the network protocol HTTPS.

This diagram shows deploying with SSL Relay and the Web Interface.


The following table lists the components of the deployment and the operating systems required for the servers and user devices.

  Components Operating systems
XenApp farm

XenApp 6.5 for Microsoft Windows Server 2008 R2

SSL Relay enabled

Secure Ticket Authority installed on XenApp server

Windows Server 2008 R2

Web server Web Interface 5.4 for Internet Information Services

Windows Server 2008 R2

Windows Server 2008

Windows Server 2003 with Service Pack 2

.NET Framework 3.5 or 2.0 (IIS 6.0 only)

Visual J#.NET 2.0 Second Edition

User devices

Citrix Receiver for Windows 3.0

TLS-enabled Web browser

Windows 7

Windows Vista

Windows XP Professional

How the Components Interact

Use HTTPS to secure the connections between users’ Web browsers and the Web Interface. Secure the connection between the Web Interface and the SSL Relay using TLS. Additionally, use TLS to secure the connections between user devices and the SSL Relay.

The SSL Relay operates as an intermediary in communication between user devices, the Web Interface, and the XML Service on each server. Each user device authenticates the SSL Relay by checking the SSL Relay’s server certificate against a list of trusted certificate authorities. After this authentication, the user device and the SSL Relay negotiate requests in encrypted form. The SSL Relay decrypts the requests and passes them to the XenApp servers. All information sent from the servers to the user device passes through the SSL Relay, which encrypts the data and forwards it to the user device to be decrypted. Message integrity checks verify that each communication has not been tampered with.

This diagram shows a detailed view of SSL Relay with the Web Interface.


Security Considerations

FIPS 140 Validation

In this deployment, the SSL Relay uses the Microsoft cryptographic service providers (CSPs) and associated cryptographic algorithms available in the Microsoft Windows CryptoAPI to encrypt and decrypt communication between user devices and servers. For more information about the FIPS 140 validation of the CSPs, see the Microsoft documentation.

SSL/TLS support and the supported ciphersuites can also be controlled using the Microsoft security option System cryptography: Use FIPS compliant algorithms for encryption, hashing, and signing for the following configurations:

XenApp farm Operating System
XenApp 6.5 Windows 7, Windows Vista, Windows XP, Windows Server 2008 R2
XenApp 6.0 Windows 7, Windows Vista, Windows XP, Windows Server 2008 R2
XenApp 5.0 Windows Server 2008, Windows Server 2003

For more information, see the documentation for your operating system.

SSL/TLS Support

You can configure the SSL Relay and the Web Interface to use either the Secure Sockets Layer 3.0 protocol or the Transport Layer Security 1.0 protocol. In this deployment, the components are configured for TLS.

When using the SSL Relay Configuration Tool, ensure that TLS is selected on the Connection tab.

Supported Ciphersuites for Sample Deployment D

In this deployment, the SSL Relay and the Web Interface can be configured to use government-approved cryptography, such as the ciphersuite RSA_WITH_3DES_EDE_CBC_SHA, to protect “sensitive but unclassified” data. When using the SSL Relay Configuration Tool, ensure that only GOV is selected on the Ciphersuite tab.

For TLS connections, you can choose other Government Ciphersuites that employ RSA key exchange and the Advanced Encryption Standard (AES).

Certificates and Certificate Authorities

Citrix products use standard Public Key Infrastructure (PKI) as a framework and trust infrastructure. In this deployment, a separate server certificate is configured for each XenApp server on which the SSL Relay is used. A root certificate is required for each user device. For information on the root certificate source for your user devices, see Citrix Receiver and Plug-ins.

Smart Card Support

In this deployment, you can configure XenApp to provide smart card authentication. To do this, you must configure authentication with Microsoft Active Directory and use the Microsoft Certificate Authority.

Plug-ins Used

In this deployment, users access their applications using Citrix Receiver. For more information about the security features and capabilities of Citrix Receiver, see Citrix Receiver and Plug-ins.