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Problem: DHCP-daemon does not work.
Symptom: You have a Linux server running as DHCP server
(dhcpd). Some clients in the network shall use dynamic ip-adresses assigned by the Linux
server, but this does not work and the following error message appears in "/var/log/messages":
dhcpd: DHCPDISCOVER from 00:60:97:8b:2a:32 via eth0
dhcpd: DHCPOFFER on 192.168.0.111 to 00:60:97:8b:2a:32 via eth0
dhcpd: sendpkt: Network is unreachable
If you check the routing table it might look like this:
[root@powerlink robert]# netstat -rn
Kernel IP routing table
Destination Gateway Genmask
Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U
1500 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U
3584 0 0
lo
Reason: The DHCPD are answering on the broadcast adress
255.255.255.255, but for the subnet 255.255.255.0 there is no route, so the server can not
reach that net. That's why the error says "Network is
unreachable".
Solution: As a workaround you can insert an extra route by
running the following command:
/sbin/route add 255.255.255.255 netmask 0.0.0.0 dev
eth0
This adds an extra route:
[root@powerlink robert]# netstat -rn
Kernel IP routing table
Destination Gateway Genmask
Flags MSS Window irtt
Iface
255.255.255.255 0.0.0.0 255.255.255.255 U
1500 0 0
eth0
192.168.0.0 0.0.0.0 255.255.255.0 U
1500 0 0
eth0
127.0.0.0 0.0.0.0 255.0.0.0
U 3584 0
0 lo
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