Strange Failure Mode in FreeBSD 4.11

[Greg Barniskis]

Martin McCormick wrote:
> 	I built a FreeBSD 4.11 system recently which is to be remotely
> installed in another town.  The system worked on our network while I
> tested it and installed several ports, etc.  We then moved it to the
> town where it is supposed to live and now, there's big trouble.
> 
> 	The Ethernet interface, known as em0 on this system, comes up
> According to all the messages.  If, however, you try to use it, it is
> as dead as a stone.  If I try to ping the local host from root, I get this:
> 
> ping: sendto: Permission denied
> ping: sendto: Permission denied
> ping: sendto: Permission denied
> 
> 	I get the same response when trying to ping real hosts over
> the network.

This smells like ipfw denial -- at least, that is the exact same 
message I get on a box where ICMP is blocked by ipfw rules. When it 
shipped, did your new box go into an IP range for which ipfw rules 
(or other filter) would apply, where maybe they did not previously 
apply on your build/test network?

> 	Pinging that system from a known good system is like pinging a
> disconnected Ethernet jack in that absolutely nothing happens.

If I'm right, you'll see that something happens, in at least the 
target IP address is ARPed for and you should see the target's MAC 
in the arp table on the known good system, even if the pings never 
return. That should at least give you confidence that the NIC in 
question is functioning insofar as it responds to an ARP request.

tcpdump is possibly your friend as well here.


-- 
Greg Barniskis, Computer Systems Integrator
South Central Library System (SCLS)
Library Interchange Network (LINK)
<gregb at scls.lib.wi.us>, (608) 266-6348