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jwlarger's avatar
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Sep 23, 2021

During which event is SNI evaluated?

Where in the event flow is SNI evaluated? And would it interfere with an iRule that fired on the same event?








3 Replies

  • Hi ,


    the earliest event you can evaluate the SNI is CLIENTSSL_CLIENTHELLO. Please see this diagram at packetpushers:

    It describes the order of iRule events in a HTTPS connection.


    How will it interfere when there is an iRule that uses the same event?

    Read this devcentral article:, pay attention to the section headlined "What happens if I have the same event in multiple iRules on a virtual server?".





  • Forget about iRules - bit of a red herring. I am familiar with the event order charts and event priorities. None of them include info about SNI.


    What I want to know is: during which event, during the normal, default course of events. without an iRule involved, is SNI evaluated and matched?

    • You listed five iRule events as examples and you asked if it could interfere with iRules. Hence my assumption was, you are asking for an iRule event.


      RFC 6066: In order to provide any of the server names, clients MAY include an extension of type "server_name" in the (extended) client hello.

      Is this the kind of event you are looking for? Or what do you understand as "default course of events"?