FC3: dhcpd.conf gets rewritten, dchpd restarts every 3-4 minutes

Problem in a nutshell:

- dhcpd.conf gets rewritten and my DNS caching server info is lost
- dhcpd gets restarted every 3-4 minutes

More details:

I have a linux FC3 box that I use as my DNS server for the Win
machines. The box has two interfaces, one attached to the ISP and the
other to the LAN [192.168.1.*]. ISP modem has the 192.168.0.1
interface. I use ipatbles for NAT, as well as bind to establish a
caching name server.

Recently, looking into logs, i discovered that my dhcpd server is being
restarted every 3-4 minutes, coinciding with dhclient asking for a
lease renewal. The modem has [Speedstream 5100B] has the lease setup
to 10 minutes.

Example [sorry for the size]:
Sep 3 23:13:15 darkstar dhclient: DHCPREQUEST on eth0 to 92.168.0.1
port 67
Sep 3 23:13:15 darkstar dhclient: DHCPACK from 192.168.0.1
Sep 3 23:13:15 darkstar dhcpd: Internet Systems Consortium DHCP Server
V3.0.1
Sep 3 23:13:15 darkstar dhcpd: Copyright 2004 Internet Systems
Consortium.
Sep 3 23:13:15 darkstar dhcpd: All rights reserved.
Sep 3 23:13:15 darkstar dhcpd: For info, please visit
http://www.isc.org/sw/dhcp/
Sep 3 23:13:15 darkstar dhcpd: dhcpd shutdown succeeded
Sep 3 23:13:15 darkstar dhcpd: dhcpd shutdown succeeded
Sep 3 23:13:15 darkstar dhcpd: Internet Systems Consortium DHCP Server
V3.0.1
Sep 3 23:13:15 darkstar dhcpd: Copyright 2004 Internet Systems
Consortium.
Sep 3 23:13:15 darkstar dhcpd: All rights reserved.
Sep 3 23:13:15 darkstar dhcpd: For info, please visit
http://www.isc.org/sw/dhcp/
Sep 3 23:13:15 darkstar dhcpd: Wrote 8 leases to leases file.
Sep 3 23:13:15 darkstar dhcpd: Internet Systems Consortium DHCP Server
V3.0.1
Sep 3 23:13:15 darkstar dhcpd: Copyright 2004 Internet Systems
Consortium.
Sep 3 23:13:15 darkstar dhcpd: All rights reserved.
Sep 3 23:13:15 darkstar dhcpd: For info, please visit
http://www.isc.org/sw/dhcp/
Sep 3 23:13:15 darkstar dhcpd: Wrote 8 leases to leases file.
Sep 3 23:13:15 darkstar dhcpd: Internet Systems Consortium DHCP Server
V3.0.1
Sep 3 23:13:15 darkstar dhcpd: Copyright 2004 Internet Systems
Consortium.
Sep 3 23:13:15 darkstar dhcpd: All rights reserved.
Sep 3 23:13:15 darkstar dhcpd: For info, please visit
http://www.isc.org/sw/dhcp/
Sep 3 23:13:15 darkstar dhcpd: Wrote 8 leases to leases file.
Sep 3 23:13:15 darkstar dhcpd: Listening on
LPF/eth1/00:a0:cc:66:16:eb/192.168.1/24
Sep 3 23:13:15 darkstar dhcpd: Listening on
LPF/eth1/00:a0:cc:66:16:eb/192.168.1/24
Sep 3 23:13:15 darkstar dhcpd: Sending on
LPF/eth1/00:a0:cc:66:16:eb/192.168.1/24
Sep 3 23:13:15 darkstar dhcpd: Sending on
Socket/fallback/fallback-net
Sep 3 23:13:15 darkstar dhcpd:
Sep 3 23:13:15 darkstar dhcpd: Sending on
LPF/eth1/00:a0:cc:66:16:eb/192.168.1/24
Sep 3 23:13:15 darkstar dhcpd: Sending on
Socket/fallback/fallback-net
Sep 3 23:13:15 darkstar dhcpd: dhcpd startup succeeded
Sep 3 23:13:15 darkstar dhcpd: dhcpd startup succeeded
Sep 3 23:13:15 darkstar dhclient: bound to xxx.yyy.6.52 -- renewal in
303 seconds.

<and, after 303 seconds>

Sep 3 23:18:18 darkstar dhclient: DHCPREQUEST on eth0 to 192.168.0.1
port 67
Sep 3 23:18:18 darkstar dhclient: DHCPACK from 192.168.0.1
Sep 3 23:18:18 darkstar dhcpd: Internet Systems Consortium DHCP Server
V3.0.1
Sep 3 23:18:18 darkstar dhcpd: Copyright 2004 Internet Systems
Consortium.
Sep 3 23:18:18 darkstar dhcpd: All rights reserved.
Sep 3 23:18:18 darkstar dhcpd: For info, please visit
http://www.isc.org/sw/dhcp/
Sep 3 23:18:18 darkstar dhcpd: dhcpd shutdown succeeded
Sep 3 23:18:18 darkstar dhcpd: dhcpd shutdown succeeded
<...>

I also discovered that dhcpd.conf is being rewritten, and that the
"option domain-name-servers" gets changed from the original 192.168.1.1
to "127.0.0.1, 192.168.0.1" [the content of my resolv.conf, pointing
to the local, caching server at 127.0.0.1 and ISP modem at
192.168.0.1]. Needless to say, that is very annoying as this means
that my Win machines will not use the linux box at 192.168.1.1 as their
[caching] DNS server.

Here is my dhcpd.conf [before being rewritten]:
authoritative;
ddns-update-style none;
deny bootp; # not using it, so, why allow it...
default-lease-time 2592000;
max-lease-time 5592000;
option subnet-mask 255.255.255.0;
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.199 192.168.1.253;
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
option domain-name-servers 127.0.0.1, 192.168.0.1;
option domain-name "mydomain.com"; # real domain name not given
in this post
}


after being rewritten, the only thing that changes is the
option domain-name-servers 127.0.0.1, 192.168.0.1;

I suspect that the dhclient is responsible for this, but could not find
anything on this topic on the net. I made sure that dhclient-script is
not overwriting my resolv.conf, however, not sure how to remove this
problem...

Any help greatly appreciated...

Regards,

IV

(E-Mail Removed) wrote:

>
> I also discovered that dhcpd.conf is being rewritten, and that the
> "option domain-name-servers" gets changed from the original 192.168.1.1
> to "127.0.0.1, 192.168.0.1"

In what you present as "Here is my dhcpd.conf [before being rewritten]:"
there is already this bogus line..

>[the content of my resolv.conf, pointing
> to the local, caching server at 127.0.0.1 and ISP modem at
> 192.168.0.1].

If your caching dns runs locally there should be *only* 127.0.0.1 in
resolv.conf
Your ISP's dns should appear only in the "forwarders" settings of your
named.conf

> Here is my dhcpd.conf [before being rewritten]:
> authoritative;
> ......................................
> option domain-name-servers 127.0.0.1, 192.168.0.1;
?? This is bad.
Try proceeding this way:
stop dhcpd ( /etc/init.d/dhcpd stop )
edit dhcpd.conf and fix it
start dhcpd

> I suspect that the dhclient is responsible for this, but could not find
> anything on this topic on the net. I made sure that dhclient-script is

By the way, i do not understand at all your whole network setup.
What does your modem do exactly? Nat ? pppoe ? dns ? dhcpd?

Olivier wrote:
> (E-Mail Removed) wrote:
>
> >
> > I also discovered that dhcpd.conf is being rewritten, and that the
> > "option domain-name-servers" gets changed from the original 192.168.1.1
> > to "127.0.0.1, 192.168.0.1"
>
> In what you present as "Here is my dhcpd.conf [before being rewritten]:"
> there is already this bogus line..
>
> >[the content of my resolv.conf, pointing
> > to the local, caching server at 127.0.0.1 and ISP modem at
> > 192.168.0.1].
>
> If your caching dns runs locally there should be *only* 127.0.0.1 in
> resolv.conf
> Your ISP's dns should appear only in the "forwarders" settings of your
> named.conf

You are correct. That is what was put there by dchlient before I found
how to prevent it from overwriting the resolv.conf.

>
> > Here is my dhcpd.conf [before being rewritten]:
> > authoritative;
> > ......................................
> > option domain-name-servers 127.0.0.1, 192.168.0.1;
> ?? This is bad.
> Try proceeding this way:
> stop dhcpd ( /etc/init.d/dhcpd stop )
> edit dhcpd.conf and fix it
> start dhcpd

My bad--before being rewritten part should have had this information:
option domain-name-servers 192.168.1.1;

Once I stop dhcpd, edit dhcpd.conf and restart the dhcpd, upon next
DHCPREQUEST, dhcpd.conf part with option domain name servers gets
rewritten and becomes:
option domain-name-servers 127.0.0.1;


>
> > I suspect that the dhclient is responsible for this, but could not find
> > anything on this topic on the net. I made sure that dhclient-script is
>
> By the way, i do not understand at all your whole network setup.
> What does your modem do exactly? Nat ? pppoe ? dns ? dhcpd?

Modem [SpeedStream 5100B] provides pppoe and has DHCP capabilities. I
have enabled an option that allows the public IP address assigned to
the modem to be used by the local LAN device [eth0 in my case].
Therefore, eth0 gets the public IP address.


Thanks,

IV