[K12OSN] DHCP, NAT or other problem. . . help!

Eric Harrison eharrison at mail.mesd.k12.or.us
Mon Jul 25 13:56:14 UTC 2005

On Mon, 25 Jul 2005, Doug Simpson wrote:

> I have a server set up for K12LTSP.
> eth0 is set to obtain IP via dhcp from another server and is connected to
> the 'external' network and it does get an ip from that network's dhcp.
> eth1 is set static to and is connected to the 'internal'
> network.

This is backwards from a default K12LTSP install. Is that correct, or is
your reversed eth0/eth1 a typo?

If it is correct, there are a couple of things that may need to be adjusted.

> A workstation connected to the internal network gets an ip in the 192.168.
> range and can ping this server, but cannot see anything on the external
> network and nothing out on the internet.
> Where can I look for a misconfiguration?

The most likely candidate is the nat service itself. By default it
expects eth1 to be the public interface, but your's is eth0. Edit
/etc/init.d/nat and change PUBLIC_ETHERNET="eth1" to

If it is still broken, the next thing I would check is the IPTables
rules. The default IPTables rules expects eth1 to be the public
interface...   If you did not alter the firewall rules during the
installation, you'll need to swap the referrences to eth0 to eth1 and
eth1 to eth0. The config file is /etc/sysconfig/iptables


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