Compressed Config

[Glenn Satchell]

>Subject: Compressed Config
>Date: Tue, 13 May 2008 15:43:10 -0400
>From: "Todd Snyder" <tsnyder at rim.com>
>
>Good day,
>
>I'm setting up a new DHCP server, which will serve about 300 new
>subnets.  My subnets are all exactly the same:
>
>subnet 172.25.1.0 netmask 255.255.255.0 {
>         range 172.25.1.16 172.25.1.254;
>         option broadcast-address 172.25.1.255;
>         option domain-name "prov0.cfg2";
>         option domain-name-servers 172.25.70.16, 172.25.65.33;
>         option routers 172.25.1.1; 
>} 
>
>And I increment my 3rd octet all the way up to 254.
>
>Same with another network.
>
>Given the sameness of all the subnets, is there a clever way to define
>these so each one isn't declared?  Something similar to the $GENERATE
>directive in named?  It seems like a lot of work when you have hundreds
>of the exact same lines, except 2 numbers changing ...
>
>I'm not fond of the number of lines in the above - my understanding is
>that I could do this as well:
>
>Subnet 172.25.1.0 netmask 255.255.255.0 { range 172.25.1.16
>172.25.1.254; option routers 172.25.1.1; }; 
>
>And define the rest of the options as a more global scope ... Am I
>mistaken?

$GENERATE is a BIND thing. Some company, different project :)

You are spot on. Broadcast address gets worked out from subnet and
netmnask, domain-name and domain-name-servers specified in global scope
is easier for the dhcp server too.

I think a simple script to generate the subnet definitions is what you
need.

eg in perl
foreach my $n in (1..254) {
  print "subnet 172.25.$n.0 netmask ....\n";
}

regards,
-glenn