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List:       freebsd-hackers
Subject:    Re: (Fwd) ip_output() does not checksum outer header
From:       Skye Poier <skye () ffwd ! cx>
Date:       2002-01-29 21:45:33
[Download RAW message or body]

Where are you capturing the network traffic?  I've noticed some checksum
weirdness in tcpdump with NICs that provide hardware checksum.

Are you seeing bad header checksums in netstat -s ?

Skye

Word on the street is that Dan Langille said:
> I am forwarding this on behalf of Bruce (his DNS is borked and thus he 
> cannot send to the lists).  Please don't CC me in the replies, only Bruce. 
> 
>  Thanks.
> 
> ------- Forwarded message follows -------
> Date sent:      	Fri, 25 Jan 2002 23:35:38 +0000
> From:           	Bruce M Simpson <bms@spc.org>
> To:             	dan@langille.org
> Subject:        	ip_output() does not checksum outer header
> 
> Dan,
> 
> if you could forward this on to freebsd-net I would be most grateful.
> 
> I have completed most of the code to implement GRE as a regular
> interface driver under 4.4-STABLE using the cloner interface. This
> has all worked fine in local tests. Tonight, whilst testing with
> a remote site, we noticed that the encapsulating IP datagram header
> around the GRE header does not have any header checksum.
> 
> I have checked, checked and re-checked the m->m_len, m->m_pkthdr.len,
> m_pullup() results et al and can find nothing out of the ordinary.
> 
> This is driving me mad right now, can anybody shed any light on the
> problem?
> 
> Regards,
> Bruce.
> 
> ------- End of forwarded message -------
> 
> -- 
> Dan Langille
> The FreeBSD Diary - http://freebsddiary.org/ - practical examples
> 
> 
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