TLS Server Name Indication
Problem this snippet solves:
Extensions to TLS encryption protocols after TLS v1.0 have added support for passing the desired servername as part of the initial encryption negotiation. This functionality makes it possible to use different SSL certificates with a single IP address by changing the server's response based on this field. This process is called Server Name Indication (http://en.wikipedia.org/wiki/Server_Name_Indication).
It is not supported on all browsers, but has a high level of support among widely-used browsers. Only use this functionality if you know the bulk of the browsers accessing your site support SNI - the fact that IE on Windows XP does not precludes the wide use of this functionality for most sites, but only for now. As older browsers begin to die off, SNI will be a good weapon in your arsenal of virtual hosting tools.
You can test if your browser supports SNI by clicking here: https://alice.sni.velox.ch/
Supported Browsers: * Internet Explorer 7 or later, on Windows Vista or higher * Mozilla Firefox 2.0 or later * Opera 8.0 or later (the TLS 1.1 protocol must be enabled) * Opera Mobile at least version 10.1 beta on Android * Google Chrome (Vista or higher. XP on Chrome 6 or newer) * Safari 2.1 or later (Mac OS X 10.5.6 or higher and Windows Vista or higher) * MobileSafari in Apple iOS 4.0 or later (8) * Windows Phone 7 * MicroB on Maemo
Unsupported Browsers: * Konqueror/KDE in any version * Internet Explorer (any version) on Windows XP * Safari on Windows XP * wget * BlackBerry Browser * Windows Mobile up to 6.5 * Android default browser (Targeted for Honeycomb but won't be fixed until next version for phone users as Honeycomb will be reserved to tablets only) * Oracle Java JSSE
Note: The iRule listed here is only supported on v10 and above.
Note: Support for SNI was added in 11.1.0. See SOL13452 for more information.
How to use this snippet:
Create a string-type datagroup to be called "tls_servername". Each hostname that needs to be supported on the VIP must be input along with its matching clientssl profile. For example, for the site "testsite.site.com" with a ClientSSL profile named "clientssl_testsite", you should add the following values to the datagroup.
String: testsite.site.com Value: clientssl_testsite
If you wish to switch pool context at the time the servername is detected in TLS, then you need to create a string-type datagroup called "tls_servername_pool". You will input each hostname to be supported by the VIP and the pool to direct the traffic towards. For the site "testsite.site.com" to be directed to the pool "testsite_pool_80", add the following to the datagroup:
String: testsite.site.com Value: testsite_pool_80
Apply the iRule below to a chosen VIP. When applied, this iRule will detect if an SNI field is present and dynamically switch the SSL profile and pool to use the configured certificate.
Important: The VIP must have a clientSSL profile AND a default pool set. If you don't set this, the iRule will likely break. There is also no real errorhandling for incorrect/inaccurate entries in the datagroup lists -- if you enter a bad value, it'll fail.
This allows you to support multiple certificates and multiple pools per VS IP address.