DHCP Server Problem

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Is it possible to setup a DHCP server that lends a range of ips to a subnet where the DHCP server doesn't have the interface?

For example the DHCP server is setup to a red hat box with only one interface card with ip 165.65.110.99.

The /etc/dhcp/dhcpd.conf is:

 

DHCPDARGS=eth0;
 
subnet 192.168.100.0 netmask 255.255.255.0 {
        option routers                  192.168.100.1;
        option subnet-mask              255.255.255.0;
 
        option domain-name              "lsnet.ucla.edu";
        option domain-name-servers       164.67.7.60, 164.67.60.60;
 
        option time-offset              -8;
 
        range 192.168.100.11 192.168.100.100;
        range 192.168.100.110 192.168.100.200;
}
 
# reservation example
host apex {
   option host-name "test.lifesci.ucla.edu";
   hardware ethernet 00:A0:78:8E:9E:AA;
   fixed-address 192.168.6.47;
}
DHCPDARGS=eth0;
 
subnet 192.168.100.0 netmask 255.255.255.0 {
        option routers                  192.168.100.1;
        option subnet-mask              255.255.255.0;
 
        option domain-name              "lsnet.ucla.edu";
        option domain-name-servers       164.67.7.60, 164.67.60.60;
 
        option time-offset              -8;
 
        range 192.168.100.11 192.168.100.100;
        range 192.168.100.110 192.168.100.200;
}
 
# reservation example
host apex {
   option host-name "test.lifesci.ucla.edu";
   hardware ethernet 00:A0:78:8E:9E:AA;
   fixed-address 192.168.6.47;
}

 

DHCPDARGS=eth0;
 
subnet 192.168.100.0 netmask 255.255.255.0 {
        option routers                  192.168.100.1;
        option subnet-mask              255.255.255.0;
 
        option domain-name              "lsnet.mydomain.org";
        option domain-name-servers       165.67.7.60, 165.67.60.60;
 
        option time-offset              -8;
 
        range 192.168.100.11 192.168.100.100;
        range 192.168.100.110 192.168.100.200;
}
 
# reservation example
host apex {
   option host-name "test.mydomain.org";
   hardware ethernet 00:A0:78:8E:9D:AA;
   fixed-address 192.168.6.47;
}
 
The red hat box where I'm running the DHCP server doesn't have a defined interfact to the newtowk 192.168.100.0.
 
After I start the service I get this in the /var/log/messages
 
May  2 16:02:29 deneb dhcpd: Wrote 0 deleted host decls to leases file.
May  2 16:02:29 deneb dhcpd: Wrote 0 new dynamic host decls to leases file.
May  2 16:02:29 deneb dhcpd: Wrote 0 leases to leases file.
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: No subnet declaration for eth0 (164.67.110.33).
May  2 16:02:29 deneb dhcpd: ** Ignoring requests on eth0.  If this is not what
May  2 16:02:29 deneb dhcpd:    you want, please write a subnet declaration
May  2 16:02:29 deneb dhcpd:    in your dhcpd.conf file for the network segment
May  2 16:02:29 deneb dhcpd:    to which interface eth0 is attached. **
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: Not configured to listen on any interfaces!
May  2
May  2 16:02:29 deneb dhcpd: Wrote 0 deleted host decls to leases file.
May  2 16:02:29 deneb dhcpd: Wrote 0 new dynamic host decls to leases file.
May  2 16:02:29 deneb dhcpd: Wrote 0 leases to leases file.
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: No subnet declaration for eth0 (164.67.110.33).
May  2 16:02:29 deneb dhcpd: ** Ignoring requests on eth0.  If this is not what
May  2 16:02:29 deneb dhcpd:    you want, please write a subnet declaration
May  2 16:02:29 deneb dhcpd:    in your dhcpd.conf file for the network segment
May  2 16:02:29 deneb dhcpd:    to which interface eth0 is attached. **
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: 
May  2 16:02:29 deneb dhcpd: Not configured to listen on any interfaces!
 
 
Could anybody shed some light on what is wrong on m configuration?
 
Thanks
Marcello

Responses

Marcello,

 

The posting is hard to read, due to lack of newlines.

So could you please add newlines to the post?

I never done this, but I guess it has to do with the DHCPARGS=eth0.

 

Are your routers configured as dhcp-helpers? If not the dhcp client in the network 192.168.100.0/255.255.255.0 will not reach your dhcp server to get ip-info.

dhcp traffic is not routed without a dchp-helper for it is a "broadcast" type of trafic.

What I do not understand in your setup: Why put the server in a different network segment?

I would only do this, if you would either try to setup a dhcp server for virtual machines running on the server itself or if you would server multiple network segment.

The latter you do not do, if I understand your configuration.

 

Kind regards,

 

ir. Jan Gerrit Kootstra