Forum Discussion

Mike757's avatar
Mike757
Icon for MVP rankMVP
Feb 11, 2023

behavior of SSL::disable serverside

Hello! I've configured an https virtual server, with an associated iRule that chooses the server pool according to the URI. The only unusual thing is that some of the pools have SSL servers and o...
application delivery
LTM iRule SSL
  • xuwen's avatar
    xuwen
    Feb 11, 2023

    Better give the config of list ltm virtual xxx and serverside tcpdump to watch whether F5 send clienthello to this pool member

    modify this iRules to test:

     

     

    when HTTP_REQUEST {
  set usessl 0
  switch -glob [string tolower [HTTP::uri]] {
    "/path1/*" {
        set usessl 1
        pool POOL-path1
        persist cookie insert cookie1
    }
    "/path2/*" {
        set usessl 1
        pool POOL-path2
        persist cookie insert cookie2
    }
    "/path3/*" {
        set usessl 0
        # SSL::disable serverside
        pool POOL-path3
    }
    default {
     set usessl 1
    }
 }
}
when SERVER_CONNECTED {
  log local0. "usessl value is $usessl"
  if { $usessl == 0 } {
    SSL::disable
  }
}

     

     

     

Mike757's avatar
Mike757
Icon for MVP rankMVP
Feb 11, 2023

Hi xuwen,

and thanks for the answer. I can indeed share my VS config (below) but it probably will take a little while to get a tcpdump (no remote access to customer).

 

ltm virtual /Common/VS-wwwq-443 {
  description "VIP https://wwwq.xxxxxxx"
  destination /Common/10.x.x.12%2:443
  ip-protocol tcp
  mask 255.255.255.255
  profiles {
    /Common/HTTP-wwwq { }
    /Common/SSL-C-wwwq {
      context clientside
    }
    /Common/serverssl {
      context serverside
    }
    /Common/tcp-lan-optimized { }
  }
  serverssl-use-sni disabled
  source 0.0.0.0%2/0
  source-address-translation {
    type automap
  }
  rules {
    IRULE-wwwq-443
  }
  translate-address enabled
  translate-port enabled
  vlans {
    /Common/VLAN-1319
  }
  vlans-enabled
}

I can also try some iRule logging, but wouldn't the SSL::disable command, without the serverside option, try to disable SSL also from clientside?

[Edit]

Just took a closer look at https://clouddocs.f5.com/api/irules/SSL__disable.html, and I see your point. Will try to test this ASAP... which might mean next Monday.

/Mike

  • xuwen's avatar
    xuwen
    Icon for Cumulonimbus rankCumulonimbus
    Feb 11, 2023

    your iRules and vs config look normal,iRules Home SSL::disable says:

    Disables SSL processing on one side of the LTM. Sends an SSL alert to the peer requesting termination of SSL processing

    is F5 send SSL alert packet on the serverside to the pool member cause this scene?

    so,you need to tcpdump in serverside watch whether F5 send ClientHello or SSL alert to the http pool member

    • Mike757's avatar
      Mike757
      Icon for MVP rankMVP
      Feb 12, 2023

      xuwen, you're the man!

      Improved iRule worked like a charm. And yes, before the changes I saw the attempt of SSL handshake with the server.

      /Mike

      • xuwen's avatar
        xuwen
        Icon for Cumulonimbus rankCumulonimbus
        Feb 12, 2023

        Because SSL:: disable describes that it will send an ssl alert message to the peer, and I'm not sure because I did not experiment with VE. 

        In short, iRules Home should simply describe the scope of use of the function, and BIGIP VE should do the experiment for the specific details. In the previous few days [TCP:: option get 28], someone directly copied the example Code displayed by CLIENT_ACCEPTED event, cause [string length [TCP::option get 28] value is 0,  Let Akamai capture packets. Akamai truely carry the tcp option 28 field, Finally, take VE to test and find that this situation should be CLIENT_DATA event use [TCP::option get 28] and not in CLIENT_ACCEPTED event

        iRules Event flow order display SSL::disable should be in CLIENT_ACCEPTED or SERVER_CONNECTED event

        Here is the link to the iRule Events flow order

        https://clouddocs.f5.com/training/community/irules/html/class1/module1/iRuleEventsFlowHTTPS.html