NetBSD Problem Report #38388

From  Tue Apr  8 21:50:32 2008
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Date: Tue,  8 Apr 2008 23:50:29 +0200 (CEST)
Subject: ipnat won't let GRE get redirected
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>Number:         38388
>Category:       kern
>Synopsis:       ipnat won't let GRE get redirected
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 08 21:55:00 +0000 2008
>Last-Modified:  Mon Jun 02 11:45:01 +0000 2008
>Originator:     Quentin Garnier
>Release:        NetBSD 4.0
	ipnat will drop incoming GRE packets if you try to redirect that

	Also, the PPTP proxy (undocumented of course) doesn't work.
	Maybe that's worth another PR, maybe not.
	Redirect GRE in any way, specifically or not.


		rdr on iface external/32 -> internal/32 gre
	or even
		rdr on iface external/32 -> internal/32

	And note that protocol 47 doesn't get through.  With the second
	line, protocol 46 and 48 do get through.
	Remove all the remaining references to IPPROTO_GRE in the code of
	ipfilter does solve the issue (but does not make the pptp proxy
	work of course).
	A lot of them are already commented out.  I'm not sure exactly
	which of the remaining ones is the culprit, but commenting them
	all out was enough for me.

From: Darren Reed <>
Subject: Re: kern/38388
Date: Mon, 02 Jun 2008 04:42:53 -0700

 At one point I was going to try and demultiplex GRE "connections" based on
 what was in the GRE header...

 If you can send me some complete packet dumps using tcpdump of live GRE
 packets then I'd be interested to see them...

 I would be curious to know which are the magic lines that when commented
 out make it work for you...


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