redirecting connections based on probability

[Max Laier]

Am Fr, 29.02.2008, 16:35, schrieb Bartosz Giza:
> Hi,
>
> I have to do such a thing like redirecting connections to port 80 based on
> probability. For example i need to redirect 10% requests to my web server
> and
> other 90% of requests should go to the original location.
>
> I know that pf has probability feature but there is no probability option
> for
> rdr rules. I have tryied couple of methods that could work but they didn't
> :(
>
> The problem is that rdr rules works on incoming packets so i can't use
> them
> dirrectly because i don't want to redirect all packets to different
> location.
>
> Could somebody tell me is such a thing possible in pf ? If yes please
> point me
> how is that possible.

Say you want to share 1/3 -> IP_A and 2/3 -> IP_B (for the sake of brevity):

     rdr on $ext_if proto tcp from any to any port 80 \
           -> { $IP_B, $IP_A, $IP_B } round-robin

This also works with random pool selection.  src-hash and bitmask are
obviously another story.  sticky-address might also skew the results, but
could be a good idea nontheless.

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