If you’re trying to do asymmetric routing in Ubuntu 12.04..

..you will need to disable rp_filter on the inbound interface. rp_filter has been enabled by default since Ubuntu 12.04, so even if it worked in earlier versions, you’ll need this setting.

You can add an “ip_rp_filter 0” line to the relevant interface in /etc/network/interfaces, and you’re golden.

3 thoughts on “If you’re trying to do asymmetric routing in Ubuntu 12.04..

  1. Rik

    Hi,

    Would it not be better to set it to 2 instead of turning it off?

    Regards,

    Rik

  2. Soren Post author

    Possibly. It’s not entirely clear to me in what situations setting it to 2 would suffice and when I need to disable it entirely.

    I should have pointed out that you should try with 2 first, and if that failed, go all the way to 0.

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