DHCP server on CentOS 5.5 not working

banexx · 12-02-2010, 02:40 AM

Hi

I'm no expert on DHCP so i come to you for help.

My problem is that i have a CentOS 5.5 server on which i want to install a DHCP server. I have two NICs where eth0 has access to the internet and where eth1 should act as an DHCP server.

I have installed dhcpd and this is how my dhcpd.conf file looks like.

Code:

ddns-update-style ad-hoc;
ignore client-updates;

default-lease-time 600;
max-lease-time 7200;

subnet 10.0.0.0 netmask 255.255.255.0 {
  range 10.0.0.2 10.0.0.25;
  option domain-name-servers 10.0.0.100;
  option routers 10.0.0.100;
  option broadcast-address 10.0.0.255;
  default-lease-time 600;
  max-lease-time 7200;
}

ifconfig looks like this

Code:

eth0      Link encap:Ethernet  HWaddr 00:1B:21:4A:F5:72
          inet addr:10.0.15.107  Bcast:10.0.15.255  Mask:255.255.255.0
          inet6 addr: fe80::21b:21ff:fe4a:f572/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4251 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4097 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:355808 (347.4 KiB)  TX bytes:516984 (504.8 KiB)

eth1      Link encap:Ethernet  HWaddr 00:04:76:F5:94:9D
          inet addr:10.0.0.100  Bcast:10.0.0.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:225 Base address:0xcc00

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:560 (560.0 b)  TX bytes:560 (560.0 b)

When i start dhcpd on eth1 i get no error messages but when i connect any devices to eth1 they don't get any IP. I cant find anything in any logs about devices trying to get an IP address.

I dont have any firewall rules in iptables.

Anyone have a hint about whats wrong?

kaushalpatel1982 · 12-02-2010, 05:47 AM

FYI, Your configuration run successfully on my centos 5.5.

I dont know what command you are using to start the DHCP server. Can you please provide output of the following :

1. do "service dhcpd restart" what is the output of the command ?
2. after running this command few lines going to add in /var/log/messages for DHCP server actions. Provide the logs.

david1941 · 12-02-2010, 06:10 AM

Check out the authoritative statement in man dhcpd.conf.

banexx · 12-02-2010, 07:07 AM

Quote:

Originally Posted by kaushalpatel1982

I dont know what command you are using to start the DHCP server.

Im using /usr/sbin/dhcpd eth1

Quote:

Originally Posted by kaushalpatel1982

1. do "service dhcpd restart" what is the output of the command ?
2. after running this command few lines going to add in /var/log/messages for DHCP server actions. Provide the logs.

1. The output from "service dhcpd restart"

Code:

Shutting down dhcpd:                                       [  OK  ]
Starting dhcpd:                                            [  OK  ]

2. From the log

Code:

Dec  2 13:58:42 xx dhcpd: Internet Systems Consortium DHCP Server V3.0.5-RedHat
Dec  2 13:58:42 xx dhcpd: Copyright 2004-2006 Internet Systems Consortium.
Dec  2 13:58:42 xx dhcpd: All rights reserved.
Dec  2 13:58:42 xx dhcpd: For info, please visit http://www.isc.org/sw/dhcp/
Dec  2 13:58:42 xx dhcpd: Wrote 0 leases to leases file.
Dec  2 13:58:42 xx dhcpd: Listening on LPF/eth1/00:04:76:f5:94:9d/10.0.0/24
Dec  2 13:58:42 xx dhcpd: Sending on   LPF/eth1/00:04:76:f5:94:9d/10.0.0/24
Dec  2 13:58:42 xx dhcpd: Sending on   Socket/fallback/fallback-net

I think that my NIC is the problem. I have tested the DHCP server on the other NIC and it just works.

kaushalpatel1982 · 12-02-2010, 07:09 AM

as you said you may have problem with you eth1 else Your service is running successfully.