Re: dhclient problems on FreeBSD-6

On Thu, Oct 20, 2005 at 01:35:28PM -0400, Forrest Aldrich wrote:
> I'm running:  6.0-BETA5 #0: Sat Oct  8 14:41:44 EDT 2005
> 
> Recently, I posted a quesiton about dhclient becoming "wedged" in the 
> mornings, it would raise the system load and basically hang.   A simple 
> kill -HUP and restart would solve the problem.
> 
> The only indication I'm seeing in the logs is:
> 
>    Oct 20 13:25:26 forrie dhclient[11061]: 5 bad IP checksums seen in 5
>    packets
> 
> 
> My provider is Comcast.   Does the above message indicate something 
> "bad" being sent from their DHCP servers or am I hitting a known bug.
> 
> The dhclient I'm using is whatever comes with the stock system build.

Sounds like the bpf input is buffer is getting mangled.  I find that
unlikely outside a hardware problem at this point, but it's possible
there's some sort of bpf bug that is triggered by your system.  The most
useful thing you could do is try to get a version of dhclient with debug
symbols to fail and find out where it's actually looping.

http://lists.freebsd.org/pipermail/freebsd-current/2005-August/054224.html

Also, if you haven't done so already try the following patch.  If it
fixes it, there's a bpf bug.

-- Brooks

Index: bpf.c
===================================================================
RCS file: /home/ncvs/src/sbin/dhclient/bpf.c,v
retrieving revision 1.6
diff -u -p -r1.6 bpf.c
--- bpf.c	23 Aug 2005 23:59:55 -0000	1.6
+++ bpf.c	24 Oct 2005 17:45:33 -0000
_at__at_ -288,7 +288,7 _at__at_ receive_packet(struct interface_info *in
 			if (length <= 0)
 				return (length);
 			interface->rbuf_offset = 0;
-			interface->rbuf_len = length;
+			interface->rbuf_len = BPF_WORDALIGN(length);
 		}
 
 		/*

-- 
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