Subject: Re: /dev/tap and tcpdump don't go together very well?
To: Rhialto <firstname.lastname@example.org>
From: Johnny Billquist <email@example.com>
Date: 04/08/2007 15:41:13
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This all reminds me of another thing.
Are there any way, or plans to be able to, change the mac address of an
ethernet interface in NetBSD? I don't think there is, but I might have
When doing stuff like Olaf is doing here, changing the MAC address might
be desireable (in his case if he wants his PDP-10 to run TOPS-20 with
DECnet enabled, since DECnet wants specific MAC addresses on interfaces...)
> On Sun 08 Apr 2007 at 06:47:14 -0400, Greg Troxel wrote:
>>Please be far more clear about how this is all supposed to work.
> I wish I could point to some easy example program, but alas. What I'm
> using involves a pdp-10 emulator with TOPS-20 (http://panda.trailing-edge.com)
> plus some private patches to add /dev/tap to it.
> (http://www.falu.nl/~rhialto/klh-diffs should be all, if I did it right)
> Is there some system program or possibly something in pkgsrc that I can
> try, that uses /dev/tap, so that we can verify independently? Writing a
> separate program that injects some packets into /dev/tap isn't so
> difficult but I am currently wondering how one would verify that they
> arrive at the other end.
>>Running tcpdump on the host as '-i tap0' will put the tap device in
>>promiscuous mode. But packets should still function in both directions.
> I looked at the source (of course) and I could find no obvious
> explanation. That's why I was wondering if perhaps it was some
> non-obvious but known problem.
>>Try adding -p to not force promiscuous mode.
> Interesting. I still see (the? all?) packets with tcpdump, but the
> telnet connection still functions. This may be a clue towards finding
> the cause.
>> Greg Troxel <firstname.lastname@example.org>
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: email@example.com || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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