[2083] in linux-net channel archive
IP forwarding bug in 1.3.73
daemon@ATHENA.MIT.EDU (Zoltan Hidvegi)
Thu Mar 14 11:29:13 1996
From: Zoltan Hidvegi <hzoli@cs.elte.hu>
To: alan@lxorguk.ukuu.org.uk, linux-net@vger.rutgers.edu
Date: Thu, 14 Mar 1996 16:42:38 +0100 (MET)
We have a ppp dial-in server running linux-1.3.73. Normally it uses 296
MRU/MTU on the ppp interfaces and 1500 MTU on the ethernet card.
Unfortunately it cannot forward UDP packages larger that 296 bytes correctly.
When I raise the MTU on the ppp line to 1500 everything works fine.
This problem showed up when sendmail asked the nameserver to resolve an
address. Sendmail use type=ANY requests and the reply can be quite large.
The reply arrived to the ppp client but with bad UPD checksum and the IP
address of the originator of the packet was also wrong. Also the size of the
bogous reply was 319 bytes despite the 296 byte MTU. As I remember tcpdump
told that it is a fragment. I can provide tcpdump output for that if required
(but I left home the floppy which contains that).
1.3.72 (or was it 1.3.71?) did not have this bug.
One more bug which is probably not related to that (in fact I did not notice
anything bad related to it but it appeared in my kernlog):
arp_cache_bind: fe06b59d backlogged
arp_find: fe06b59d backlogged
arp_run_bh: fe06b59d reinstalled
arp_run_bh: entry fe06b59d was born dead
Bye,
Zoltan
