Dropping of network connection on Linux system

[gaf at blu.org (Jerry Feldman)]

I'm going to take a stab at this one also based on some of the problems I 
had with DHCP when I was running older versions of SuSE.
First, Linux will not drop a connection with a static IP unless either there 
is a hardware problem, or if you have a PC card and shake it lose. 
These are not your problem, but I wanted to isolate the problem to dhcp.

Next, your DHCP Client should log its activities. It also should be running 
as a daemon. There are several DHCP clients and the configurations are 
a bit different. 

Lets look at some scenarios:
First, you establish the initial connection and the DHCP client exits. This 
is unlikely. 
Second, your lease expires. The lease is established by the DHCP 
server, and can be short (minutes) or long (months). The dhcp client tries 
unsuccessfully to reacquire the lease. Result, your IP address is 
dropped. 

You really need to look at your logs on both the client and the server 
side. I suspect that your dhcp client is failing to reacquire the lease. In 
addition to the logs, dhcp also maintains a database (depends on the 
client, but on SuSE is was somewhere like /var/state/dhcpclient. I found 
that there was a bug in the client that would cause it to fail to acquire a 
lease when the dates were out of sync. I went into the database and 
tweaked the dates and it worked. (Note that the last couple of releases of 
SuSE have worked flawlessly). I currently use SuSE 7.1, and my laptop 
acquires a lease at Compaq, Northeastern U and home with no problem.
Jerry Feldman <gaf at blu.org>
Associate Director
Boston Linux and Unix user group
http://www.blu.org
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