Private in-house domain

[Stephen Ryan]

On Tue, 2007-05-15 at 20:10 -0400, Tech Writer wrote:
> Thanks for all of the suggestions, so far.  I'm going to look at them more 
> carefully, and see if I can fix this by changing my routing table.
> 
> Both replies suggested that I change my internal domain to a 192.168.1.x IP 
> range (to match the Linksys) or change my Linksys router to the 10.25.1.x 
> range (to match my mini-domain).  Actually, I'm aware that either of these 
> will work.  My goal was to try NOT to do this.  I purposely wanted my "mini 
> domain" to have a different IP range, since I will eventually have to set 
> this demo up in a larger lab.  When I move my sample, I will not be able to 
> have any control over the DHCP server in the larger lab environment (to 
> change its IP address) nor will I be able to define my own IP addresses 
> (which my domain server will need to do) in the range that the existing DHCP 
> server already owns.
> 
> So, my goal is to try to find a way to set up a mini-domain of 10.25.1.x 
> addresses within a LAN that's already set up with DHCP-assigned 192.168.1.n 
> addresses.
> 
> I hope that makes sense.

Yes, it does; you'll have to go the "create an additional route" method,
then.

If you don't need to access the rest of the surrounding network, a
static route just to the gateway will do; something like this:

$ sudo route add -host 192.168.1.1 dev eth0

If you do need to access the rest of the local network, too, then you'll
need a network route, like this:

$ sudo route add -net 192.168.1.0 netmask 255.255.255.0 dev eth0

Normally, there is a script that automatically runs these commands,
filling in the values from ifcfg-eth0.txt, but they are only set up for
simple networks; you'll need to find someplace to put the "route
add ..." command to have it run automatically on boot.

Either way, this gives the network stack information about where to send
packets destined for your gateway.

> >> ...  I'm not familiar with
> >> CentOS, so I don't know if there's an easy way to do that.
> >>
> 
> btw... CentOS is just Red Hat Enterprise Linux, with a different logo.

Thanks; I was aware of that, but I'm not familiar with RHEL, either.
I've got 10 years of Debian in my fingers, and 1 month of RHEL.  If it
was a Debian-based system, I'd tell you to put the extra route commands
in /etc/network/interfaces as a 'post-up' option.  As it is, somebody
with more RedHat-fu will have to answer that part.