kern/139204: [arp] DHCP server replies rejected, ARP entry lost before max_age

[Nikolai Saoukh]

The following reply was made to PR kern/139204; it has been noted by GNATS.

From: Nikolai Saoukh <nikolai.saoukh at gmail.com>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/139204: [arp] DHCP server replies rejected, ARP entry lost 
	before max_age
Date: Sat, 10 Oct 2009 13:25:46 +0400

 > I'm going to make a guess that this is ARP-related, based on a comment
 > in the PR.
 
 After some inspection I think the problem is in /sbin/dhclient.
 
 Patch in PR bin/96018 introduced unicast REQUESTs. That requests are
 sent from random port (not from bootpc (68)), thus defeating bpf
 filter in dhclient for replies. Moreover when there are two or more
 interfaces on the same network, that requests can be transmitted from
 another interface (with different ethernet address). IP packet with
 the same IP number (but changed ethernet address) confuse ARP
 machinery.
 
 See also PR ports/139405.
 
 IMHO, category, severity, ... of this PR should be edited.