Subject: kern/17867: UDP broadcast is broken
To: None <firstname.lastname@example.org>
From: None <email@example.com>
Date: 08/07/2002 03:01:27
>Synopsis: UDP broadcast is broken
>Arrival-Date: Wed Aug 07 03:02:00 PDT 2002
>Originator: Emmanuel Dreyfus
The NetBSD Project
NetBSD mmX 1.6_BETA5 NetBSD 1.6_BETA5 (GENERIC) #0: Fri Aug 2 19:35:27 UTC 2002 firstname.lastname@example.org:/autobuild/i386/OBJ/autobuild/src/sys/arch/i386/compile/GENERIC i386
When sending UDP/IP packets to a broadcast address on 1.6_BETA5, the generated packets are corrupted.
Here are tcpdump outputs on 1.6_BETA5:
10:39:23.484316 truncated-ip - 9945 bytes missing!mmX.info.local.65506 > 192.168.3.255.4000: udp 782
and on 1.5.3:
10:50:35.352326 mmX.info.local.65534 > 192.168.3.255.4000: udp 782
The two dumps are caused by exactly the same command (netcat), ran on
the same machine, with just the OS changed. The problem exists on
1.6BETA_5 when using a netcat built on 1.6BETA5 and a netcat built on
1.5.3, so this is not a binary compatibility problem.
Additionnaly, I discovered the problem with a home grown program,
so it is not netcat specific. I beleive the problem happens in sendto()
Of course no host on the LAN is able to understand the packets sent
by NetBSD-1.6BETA5, so this is quite serious. I have not checked if
multicast programs are affected.
simple test with netcat such as
nc -u -b 192.168.3.255 < /etc/passwd
while dumping packets with tcpdump on another machine will show the problem
not known yet.