dhcpd setup

Josh328 · 10-19-2005, 04:47 PM

I'm seting up a basic DHCP server, and I have a few questions...
I want infinite lease times to "known" clients and short lease times to "unknown clients".
Here's what I've got, basically pulled straight from the man pages. I have some questions throughout... Any help would be appreciated. Thanks..

Code:

       subnet 192.168.3.0 netmask 255.255.255.0 {
         option routers 127.0.0.1;  #THE ROUTER/FIREWALL IS RUNNING LOCALLY

         # Unknown clients get this pool.
         pool {
           option domain-name-servers 127.0.0.1; #BIND WILL ALSO RUN LOCALLY
           max-lease-time 300;
           range 192.168.3.200 192.168.3.253;
           allow unknown-clients;  #HOW ARE 'unknown-clients' DEFINED? AS A GROUP?
         }

         # Known clients get this pool.
         pool {
           option domain-name-servers 127.0.0.1;
           max-lease-time 28800;   #HOW BIG CAN THIS BE?
           range 192.168.3.5 192.168.3.199;
           deny unknown-clients;
         }
       }

SirGertrude · 10-19-2005, 06:29 PM

Known clients are simply clients that have been defined using the "host" parameter.

Code:

host Todd { hardware ethernet 00:E0:18:9B:B3:2C; }
host Bill { hardware ethernet 00:11:d8:70:6b:04; }
host Don { hardware ethernet 00:50:8D:AE:07:27; }

You can have the host defined in a group if you want.

Code:

group {
	next-server 192.168.0.129;
	host Todd { hardware ethernet 00:E0:18:9B:B3:2C; }
	host Bill { hardware ethernet 00:11:d8:70:6b:04; }
	host Don { hardware ethernet 00:50:8D:AE:07:27; }
}

This is the same as above except parameters here affect all group members.

If you were to incorporate either of the two above examples in your configuration the �unknown-clients� would be any machines with mac addresses not set in a �host� parameter. Hope this helps.

Josh328 · 10-19-2005, 06:33 PM

ok, that makes sense. so this should be fine...

Code:

       host one { hardware ethernet 00:E0:18:9B:B3:2C; }
       host two { hardware ethernet 00:11:d8:70:6b:04; }
       host three { hardware ethernet 00:50:8D:AE:07:27; }

       subnet 192.168.3.0 netmask 255.255.255.0 {
         option routers 127.0.0.1;  #THE ROUTER/FIREWALL IS RUNNING LOCALLY

         # Unknown clients get this pool.
         pool {
           option domain-name-servers 127.0.0.1; #BIND WILL ALSO RUN LOCALLY
           max-lease-time 300;
           range 192.168.3.200 192.168.3.253;
           allow unknown-clients;
         }

         # Known clients get this pool.
         pool {
           option domain-name-servers 127.0.0.1;
           max-lease-time 28800;   #HOW BIG CAN THIS BE?
           range 192.168.3.2 192.168.3.199;
           deny unknown-clients;
         }
       }

how large can the max and default lease times be? I'd like known host lease times to be infinite.

Thanks,
Josh

SirGertrude · 10-21-2005, 08:51 PM

Quote:

how large can the max and default lease times be? I'd like known host lease times to be infinite.

I'm not sure how long the lease can be, but I am pretty sure it cannot be infinite. It is not wise to have an infinite lease because you may fill your DHCP pool (especially if you pass many computers through your network) and run into problems. I have always set static DHCP leases to overcome the problem of infinite leases.

Code:

host Jack {
	hardware ethernet 00:04:61:98:E9:EC;
	fixed-address 192.168.1.2;
	}

Using the above example, the DHCP server will read the host statement and assign the specified fixed address to the host. It is a good idea to leave any fixed addresses out of the DHCP range so the IP addresses are always available for the hosts to which they belong.