IP Address Problems

[Michael J. Lynch]

Roger Haxton wrote:
> On Tuesday 10 January 2006 08:58, Derek Broughton wrote:
> 
>>The "name" business is simple to fix.  Add:
>>        send host-name NAME;
>>to your dhclient.conf
>>--
>>derek
> 
> 
> Ok, that change is easy enough to make, but why isn't it honoring the DHCP 
> lease time from my DHCP server?  I checked today and I have a different IP 
> address than the one I had yesterday.  The lease time on the server is 30 
> days.  I should hardly ever see a new IP address on my box.  The DHCP server 
> here at the office is Win2k FWIW.  Like I said, when my laptop ran SuSE, it 
> honored the lease time.  I don't know if the difference is that SuSE uses 
> dhcpcd vs. the dhclient3 that Ubuntu uses.

I don't think it's a dhcpcd vs. dhclient3 issue.  I'm using both 5.04
(Hoary) and 5.10 (Breezy) here with DHCP and neither have any sort of
issue like the one seen.  As a matter of fact, the machines do get the
same IP address assigned each time I reboot them.

I really suspect a problem with configuration or something on your end.
That being said, it's strange that the problem is occurring on two
different machines.

Just out of curiosity, how do you know how long the server lease times
are?  One other note, it's the server end that enforces the lease times
not the client (your) end.  When your machine initializes its network
via dhcp, it sends a DHCPDISCOVER request to the server.  When the
server receives it, the MAC address is checked against existing leases
and if one exists, the IP address from that lease is assigned.  You
*can* be assigned a different IP address if the IP address you *were*
assigned got re-assigned between the time you disconnected and when you
reconnect.

You mentioned that your ISP is complaining because they are running out
of IP addresses to assign.  This would suggest that their DHCP server
is, in fact, assigning you a different IP address because the one you
had previously got re-assigned.

Take a look at /var/log/syslog.  There should be some entries tagged
*dhclient*.  These should show the request and ack sequence exchange
with the server.  It should also show the IP address assigned by
the server and the renewal time (in seconds).  Post the info if you
can.

-- 
Michael J. Lynch

What if the hokey pokey IS what it's all about -- author unknown