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kbk491's avatar
kbk491
Icon for Altostratus rankAltostratus
Aug 11, 2022

Using an irule/other method to preserve source ip

Can anyone help me with an irule to preserve source ip address based on nodes being selected in a pool?

Thank you.

application delivery

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  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    Aug 12, 2022

    Maybe I am not understanding the question.

     

    But is there a reason you can't disable SNAT? Or do you mean selectively disable it?

     

    H

    • kbk491's avatar
      kbk491
      Icon for Altostratus rankAltostratus
      Aug 12, 2022

      so we can accomplish this by disabling snat? i didnt try that yet. Is that a valid method for this scenario? thanks

    • kbk491's avatar
      kbk491
      Icon for Altostratus rankAltostratus
      Aug 12, 2022

      i have not talked to the server guys yet so it may or may not need selectively disabling so just preparing in advance in case it needs it, in that case i will need to create an irule right? Which is what i need help with.

    • kbk491's avatar
      kbk491
      Icon for Altostratus rankAltostratus
      Aug 12, 2022

      so we have a working pool which is not in production and tried testing it with that by changing address translation from auto map (can rach the side from client with auto map on) to none and on the packet capture it seems to work as it should as the source is no longer getting translated but im no longer able to get to the website, im assuming i need to change something else to get it to work?  By the way im using an ssl profile for both client and server side.

  • Mayur_Sutare's avatar
    Mayur_Sutare
    Icon for MVP rankMVP
    Aug 12, 2022

    Hi kbk491 ,

    Just changing SNAT settings to none is not going to work here. In order to work this, you should have backend server default gateway pointed to the F5. Then only it will work or else it will create asymmetric routing issue and url won't work. It seems you are having the same issue. 

    To achieve your requirement,

    1. You can enable XFF settings to preserve the true client IP when SNAT is enabled. Below article will help you on it.

    https://support.f5.com/csp/article/K4816

    2. If you want to try with disabling SNAT settings, then make sure backend app server default gateway is pointed to F5. But it will cause your internet traffic also sending to F5 first. So you need to take that into consideration. 

    Hope it helps!