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Centos v.5, DHCP server running but not responding to clients

Posted on 2008-10-20
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Last Modified: 2013-12-16
Hey All,

So Ive recently installed a Centos v.5 server (the frontend of a ROCKs cluster for those of you familiar with it) however, the DHCP server is not functioning.

When I boot a client who attempts to get a DHCP address from the server, the clients packets reach the server (determined with tcpdump) however the server never responds with a packet back to the client with an address.

The dhcpd daemon is running, there appears to be nothing unusual with the /etc/dhcpd.conf file, and I cant find any errors in any logs (although I may not be looking in the right place).

Any suggestions?

Thanks!
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Question by:Mike R.
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kyleb84 earned 250 total points
ID: 22763622
Then do a "tail -f /var/log/messages" and watch for DHCP requests, if the DHCP daemon is running it'll print when a client makes a request.

If nothing comes up, please do an "iptables-save > iptables.cfg" and post that file "iptables.cfg"

If your DHCP server isn't a gateway, do a
- "service iptables stop"
- "chkconfig iptables off"
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by:kyleb84
ID: 22763630
Also if you do a:
cat /var/log/messages | grep dhcpd
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by:kyleb84
ID: 22763644
sorry accidentally click submit...

If you do the above, try copy the contents of it's output and paste it in here.
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LVL 3

Author Comment

by:Mike R.
ID: 22769705
So, here's some interesting tidbits from /var/log/messages...

[root@azumaseki log]# grep -i dhcp ./messages
Oct 20 14:39:26 azumaseki dhcpd: DHCPDISCOVER from 00:1b:fc:5f:c6:6c via eth0: network 10/8: no free leases
Oct 20 14:43:03 azumaseki dhcpd: DHCPDISCOVER from 00:1b:fc:5f:c6:6c via eth0: network 10/8: no free leases
Oct 20 21:48:15 azumaseki sshd[17390]: pam_succeed_if(sshd:auth): error retrieving information about user dhcp

So, the requests are getting to the host, but it doesn't seem to think there are free leases. How do I correct this.

I'm not sure if the PAM authentication is related...?

Thanks!
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Assisted Solution

by:Static-shock
Static-shock earned 250 total points
ID: 22772010
From the message it seems your dhcp pool is all been allocated. How long are you leases and whats the range of IP address in the pool.

Here is an example of mine it will allocate ip address 192.168.1.60-90.
subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.60 192.168.1.90;
  option broadcast-address 192.168.1.255;
  #option routers ourrouter.thatisanexample.com;
}

Here is how you set the lease time
default-lease-time 3600;
max-lease-time 7200;

Hope this helps.
Cheers
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Expert Comment

by:Static-shock
ID: 22772034
Regardless ether increase your pool or turn down the lease time.

Then have your windows client do a "ipconfig /release" and "ipconfig /renew"

After restarting your dhcpd server of course /etc/init.d/dhcpd restart

Hope this helps.
Cheers
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Author Comment

by:Mike R.
ID: 22788966
Thanks for all the input. Actually, as it turns out, it was a ROCKs 5 specific issue. Normally ROCKs requires there to be a /home/install directory...but in v5 they changed that directory location and forgot to tell the rest of the system :-)

I manually created a link for /home/instal, and now it's working fine.

Thanks again for the help and points to everyone for effort :-)
M
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