Subject: Re: [PATCH/RFC 01/10] Implement local diversion of IPv4 skbs

From: Patrick McHardy <[email-masked]>
Date: Wed, 10 Jan 2007 14:42:52 +0100

Ingo Oeser wrote:
> Patrick McHardy schrieb:
> 
>>We support bitwise use of the mark everywhere in current kernels, so
>>that shouldn't be a problem anymore.
> 
> 
> For firewall mark based policy routing to work, one must still disable 
> rp_filter, because this lookup doesn't take the mark into account[1].

If distributions wouldn't enable it by default there would be no need
to disable it again :)

> So this statement is not quite true, although I believe you are probably right 
> for this case.
> 
> BTW: This rp_filter=0 requirement isn't even officially documented 
> 	(e.g. in the LARTC).

The kernel defaults to rp_filter = 0.

> [1] But does take TOS into account for historic (???) reasons.

With TOS the assumption of symetry is a bit more realistic than
with fwmarks, but it will probably still not work properly if
you actually use routing by TOS value.