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From: Stuart Lynne <sl@whiskey.enposte.net>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] u32 nexthdr problem
Date: Sat, 30 Jun 2001 22:50:18 +0000	[thread overview]
Message-ID: <marc-lartc-99394374501221@msgid-missing> (raw)
In-Reply-To: <marc-lartc-99385197003270@msgid-missing>

In article <993851937.8529@whiskey.enposte.net>,
Don Cohen <don-lartc@isis.compsvcs.comwrote:
>I'm having trouble with nexthdr.
> tc filter add dev eth0 protocol ip parent 10:0 prio 1 u32 \
> match ip protocol 0x6 0xff match u8 0x02 0x12 at nexthdr+13 flowid 10:3
>fails to match my test packets whereas
> tc filter add dev eth0 protocol ip parent 10:0 prio 1 u32 \
> match ip protocol 0x6 0xff match u8 0x02 0x12 at 33 flowid 10:3
>does match them.
>Of course, the second one is really wrong since it means something
>totally different if your packet contains any IP options (which my
>test packets do not, of course).
>
>Does anyone either see what I'm doing wrong?
>Anyone else experience the same problems?
>Anyone know how to fix them?

The last time I looked at nexthdr (circa 2.4.0) it appeared to simply not
be fully implemented. 

I was trying to match tcp acks:

    # match acks using nexthdr - doesn't currently work
    tc filter add dev eth0 parent 20:0 protocol ip prio 10 u32 \
           match ip protocol 6 0xff \
           match u8 0x10 0xff at nexthdr+13 \
           flowid 20:23

And had to do it the hard way:

    # match acks the hard way, 
    #       IP protocol 6, 
    #       IP header length 0x5(32 bit words), 
    #       IP Total length 0x34
    #       TCP ack set (bit 5, offset 33)
    tc filter add dev eth0 parent 20:0 protocol ip prio 10 u32 \
	    match ip protocol 6 0xff \
	    match u8 0x05 0x0f at 0 \
	    match u8 0x34 0xff at 3 \
	    match u8 0x10 0xff at 33 \
	    flowid 20:23

Which of course only works with normal sized IP headers.

Has nexthdr been finished?

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Stuart Lynne <sl@fireplug.net      www.fireplug.net        604-461-7532


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      reply	other threads:[~2001-06-30 22:50 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-06-29 21:59 [LARTC] u32 nexthdr problem Don Cohen
2001-06-30 22:50 ` Stuart Lynne [this message]

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