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From: rhialto@polder.ubc.kun.nl (Olaf Seibert)
Newsgroups: comp.unix.bsd.netbsd.misc
Subject: Suspected broadcast bug
Date: 2 Aug 95 20:46:48 GMT
Organization: University of Nijmegen, The Netherlands
Lines: 51
Message-ID: <rhialto.807396408@polder.ubc.kun.nl>
NNTP-Posting-Host: polder.ubc.kun.nl
Organisation: Polderland Language & Speech Technology
(This is with NetBSD/i386 1.0 with 3c509 ethernet card, but may be
independent of that info)
Below I included a fragment of output from tcpdump, called as tcpdump -v
-l -e -x with the following expression:
( ether broadcast ) or
(
( not ip ) and
( not ( ether src 00:00:0c:01:9a:87 and ether dst 00:00:0c:01:9a:87 ) )
)
(the excluded ethernet address is the local gateway):
22:24:45.603313 1:28:27:5f:0:0 2:0:0:0:45:0 4011 300:
1deb 83ae 1520 83ae 17ff 020d 020d 0114
7192 0301 aaf0 0000 0000 f031 3230 706f
6c64 6572 2e75 6263 2e6b 756e 2e6e 6c00
0710 8dba 0710
22:24:45.603399 0:60:8c:67:c2:3d ff:ff:ff:ff:ff:ff ip 310: polder.ubc.kun.nl.timed > 131.174.23.255.timed: udp 268 (ttl 64, id 10079)
4500 2801 5f27 0000 4011 1deb 83ae 1520
83ae 17ff 0d02 0d02 1401 7192 0301 aaf0
0000 0000 f031 3230 706f 6c64 6572 2e75
6263 2e6b 756e
The first frame is weird - the source address in it changes every time
and it is of an unknown protocol.
You will notice that the weird (first) frame is about the same as the
correct (second) frame minus its first 10 bytes. These bytes end up in
the Ethernet header.
Since the bad frame comes first, I would suspect a bug in NetBSD. OTOH
we have some other network trouble here the last few days, so maybe the
erroneous frame is generated externally and the order we see the frames
in is simply wrong.
Can anybody reproduce this behaviour? To get timed to do its thing,
restart it (as root), if you like with "-d -t" as arguments.
Our network interface is configured thusly:
ep0: flags=8963<UP,BROADCAST,NOTRAILERS,RUNNING,PROMISC,SIMPLEX,MULTICAST>
inet 131.174.21.32 netmask 0xfffffc00 broadcast 131.174.23.255
Please reply by mail since I rarely have time to read this group
(unfortunately).
-Olaf.
--
___ Olaf 'Rhialto' Seibert D787B44DFC896063 4CBB95A5BD1DAA96
\X/ There are no lemurs in this post rhialto@polder.ubc.kun.nl