Forum Discussion

Lead's avatar
Lead
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Jan 13, 2023

irule creation based on Host Address contains IP Address

help in creating irule for disabling ASM policy when traffic from certain Source IP address and violation triggered as Host header contains IP address

application delivery
  • Mohamed_Ahmed_Kansoh's avatar
    Mohamed_Ahmed_Kansoh
    Icon for MVP rankMVP
    Jan 13, 2023

    Hi Lead ,

    Do you want to allow users to access your web service directly from ip without DNS resolution or what ?? 

    Or 

    Do you want to disable ASM policy from inspecting certain source ip address ? 

    Could you please clarify more ?

  • CA_Valli's avatar
    CA_Valli
    Icon for MVP rankMVP
    Jan 13, 2023

    Assuming that HTTP::host will always match VS IP:

    when HTTP_REQUEST {
  if {[HTTP::host] eq [IP::local_addr] }{ ASM::disable }
}
    • Lead's avatar
      Lead
      Icon for Nimbostratus rankNimbostratus
      Jan 13, 2023

      Hi,

      Additionaly we want 1 more condition if request blocked under ASM violation (Host header contain IP address)

      then only it gets allowed and for other violation it should gets blocked only.

       

      Thanks,

      Amit

      • CA_Valli's avatar
        CA_Valli
        Icon for MVP rankMVP
        Jan 13, 2023

         

        Hello, I've been messing with lab a little and I've seen that this violation triggers "HTTP protocol compliance failed" violation with "HTTP parser attack" (I'm running v13.x) 

        So, according to https://clouddocs.f5.com/api/irules/ASM__violation_data.html  we should be able to intercept this running the following:

         

        when HTTP_REQUEST {
  set bypass 0
  if {[IP::client_addr] eq "10.0.0.1" && [HTTP::host] eq [IP::local_addr]}{ set bypass 1 }
}
when ASM_REQUEST_DONE {
  if {$bypass}{
     if {[ASM::violation names] eq "VIOLATION_HTTP_SANITY_CHECK_FAILED" && [ASM::violation attack_types] eq "ATTACK_TYPE_HTTP_PARSER_ATTACK" }{ ASM::unblock }
  }
}

         

         

        I've tested this but had no success, as ASM_REQUEST_DONE seems to never fire in my lab amongst with all ASM_* events for some reason .. I'll look into that when I have some more free time next week.

         

  • Lead's avatar
    Lead
    Icon for Nimbostratus rankNimbostratus
    Jan 13, 2023

    Hi,

    If request come from specific IP instead of getting it blocked under ASM violation as (Host Header contains IP address)  we want request to be allowed with the help of irule. 

    Thanks,

    Lead

      • Lead's avatar
        Lead
        Icon for Nimbostratus rankNimbostratus
        Jan 13, 2023

        Yes it will work, but it will allowed all the traffic

         

        Thanks,

        Amit

    • Paulius's avatar
      Paulius
      Icon for MVP rankMVP
      Jan 13, 2023

      Lead Because you want to first match a function of the ASM policy and then disable the ASM policy I do not believe this is possible because it's an all or nothing from what I can tell in process order.