Problems with Linksys WRT54GS Routers and Potential Intercepted DHCPACKS causing IP Conflicts

[Joel Dunifon]

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Joel Dunifon
Sent: Friday, April 14, 2006 10:42 AM
To: dhcp-users at isc.org
Subject: Problems with Linksys WRT54GS Routers and Potential Intercepted
DHCPACKS causing IP Conflicts


WRT54GS Linksys Wireless-G routers on my network.  As I mentioned in my
previous message (my problem was resolved, BTW, and was related to the
max execution time setting in php.ini), I am running a static isc dhcp
v3.0.3 configuration where client host MAC addresses are entered into a
php-mysql interface which builds the dhcp configuration and restarts the
dhcpd process.
 
    The behavior I am seeing is that a customer with a Linksys router
will call in with no connectivity, and no IP address can be obtained by
the router.  Looking at DHCP logs, I see repeated 'DHCPDECLINE' messages
for the customer's router.  After checking for an ARP entry for his IP,
I find another Linksys Router is using his address.  I check for dhcp
logs for the second router and find nothing, or in a few cases I am
actually found DHCPDECLINE messages for router #2 and a third router
that is using the second customer's address!  After contacting the owner
of the 'thieving' router and checking settings, we have been able to
confirm that the router is using the first customer's IP.  A manual
release/renew on the second customer's router results in a pull of the
proper address.  
 
    This only seems to be affecting the newest WRT54GS routers that
linksys makes.  I assume this is some sort of firmware bug.  Contacts to
Linksys have, unsuprisingly, been a huge waste of time.  A year or so
ago, we were having widespread problems with Linksys BEFSR41 Routers
locking up randomly and requiring a power cycle.  I ended up
mass-mailing my users and requesting they all update their firmware.
Within a few days, the problem was nearly gone.
 
    Anyone else seeing this?
 
    There was a time that I was an avid Linksys user.  Those days are
far over.  I can appreciate the possibility that other vendors have
these problems as well and that the fact that Linksys has such a huge
market share seems to magnify issues when they arise.  However, the
support and treatment I have received from the company have been awful.