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 From:  Christoph Gysin <cgysin at gmx dot ch>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  DHCP client problem
 Date:  Mon, 24 Jan 2005 19:58:33 +0100
It seems that my ISP has recently changed its DHCP server configuration. 
My IP changed about every 24h. Now, I receive an IP with a lease time of 
~1600s, which is a change every half an hour.

 From my System logs (public IP's hidden):

Jan 24 19:09:22:
dhclient: DHCPDISCOVER on sis2 to 255.255.255.255 port 67 interval 7
dhclient: DHCPOFFER from 10.182.192.1
dhclient: DHCPREQUEST on sis2 to 255.255.255.255 port 67
dhclient: DHCPACK from 10.182.192.1
dhclient: New Network Number: x.x.x.x
dhclient: New Broadcast Address: 255.255.255.255
dhclient: New IP Address (sis2): x.x.x.x
dhclient: New Subnet Mask (sis2): 255.255.240.0
dhclient: New Broadcast Address (sis2): 255.255.255.255
dhclient: New Routers: x.x.x.x
dhclient: bound to x.x.x.x -- renewal in 1618 seconds.

About 1618 seconds later, dhclient tries to refresh it's lease:

Jan 24 19:36:20:
dhclient: DHCPREQUEST on sis2 to y.y.y.y port 67
last message repeated 14 times

As you can see, the DHCPACK came from 10.182.192.1, a private IP. The 
second DHCPREQUEST, is sent to y.y.y.y, which is a completly different 
address (no private net). dhclient retries the DHCPREQUEST to y.y.y.y 
about 50 minutes, before it does a DHCPREQUEST to 255.255.255.255. After 
that, I get a new lease from a different DHCP server.

Now my Internet connection works 30 minutes, then it goes down for about 
50 minutes. Is there a way to tell dhclient to always send DHCPREQUEST's 
to the broadcast address?

Christoph Gysin

PS: I configured monowall to block private nets, why does the DHCPOFFER 
from 10.182.192.1 get through?
-- 
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