netdev - Re: Need a creative way to negate u32 filter matches

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Date:	Fri, 29 May 2015 23:36:34 -0400
From:	"John A. Sullivan III" <jsullivan@...nsourcedevel.com>
To:	netdev <netdev@...r.kernel.org>
Subject: Re: Need a creative way to negate u32 filter matches

On Fri, 2015-05-29 at 22:32 -0400, John A. Sullivan III wrote:
> Hello, all.  I understand there is no direct way to negate a u32 match.
> I have a setup where I am redirecting all ingress traffic from the
> physical interface to an ifb interface with a u32 match u8 0 0 action
> mirred egress redirect filter attached to ffff:
> 
> I do not want to send ingress ESP packets to the IFB interface.  How do
> I exclude those?
> I tried creating a filter with a lower prio and added before the above
> rule which matches ESP packets and does nothing with them (action pass)
> in the hope that it would be the first match and ESP packets would then
> not be matched against the second filter.  That does not appear to be
> working from tc -s filter.  The rule is hit, the match succeeds, but the
> success count is 0 and I see the filter on the IFB interface which
> identifies ESP packets is successfully being hit.
> 
> How do I redirect all packets EXCEPT ESP packets to an IFB interface?
> Thanks - John

I just stumbled across ematch.  This seems to do the trick by allowing
negation - John

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