Subject: Re: Stripping GRE Too Early?
To: Curt Sampson <firstname.lastname@example.org>
From: None <email@example.com>
Date: 01/07/2000 06:55:21
>>It seems that under NetBSD 1.4.1, at least, when you set up a gre tunnel
>>between two machines, the `real' interface that the tunnel's packets pass
>>over is showing de-encapsulated incoming packets to bpf, ipfilter, etc.
>>(Outgoing are shown encapsulated.) Here's an example:
>>16:33:38.755359 fmh.blink.com > 192.168.10.32: icmp: echo request (gre encap)
>>16:33:38.788769 192.168.10.32 > fmh.blink.com: icmp: echo reply
>>What's up with this? Does current still do it?
> bpf sends encapsulated packet to userland.
> NetBSD 1.4.1 tcpdump(8) skips outer header, if you don't have -v on
> command line. If you have -v, it will print like this:
>>16:33:38.755359 fmh.blink.com > 192.168.10.32: gre 10.1.1.1 > 10.1.1.2: icmp: echo request (gre encap)
> I think this is a bit confusing that the order is reversed.
I may be wrong about the above 1.4.1 example; anyway, -v should help