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

Doug Simpson simpsond at leopards.k12.ar.us
Mon Jul 25 14:44:06 UTC 2005

On Mon, 25 Jul 2005, Doug Simpson wrote:

> On Mon, 25 Jul 2005, Eric Harrison wrote:
> > 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?
> Actually, the default install did not set up the eth0 and eth1. I had to 
> set them post-install.  For some reason the installer didn't detect the 
> interfaces until after the first reboot.
> > 
> > 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
> I didn't touch iptables during install (don't know anything about iptables 
> at all. . .)
> Think the best way would be to just re-configure the eth(x) interfaces to 
> the default setting aand see if itmwilol work that way?
> That will be easier and probably better.
> Thank you for your quick response!
> Doug

I set then interfaces correctly. Obtain by DHCP on eth1 and set static on 

Now, that server won't see out of itself to internet or anywhere except 
the 'internal' network.

A workstation will get an internal IP and can see the server but nothing 

Do I just need to start over and try to remember which interface is which 
when it wants the info during the install?  Since it doesn't detect any 
interfaces during the install, it goofs up the settings and apparently the 
install program don't know how to handle it. It detects the interfaces 
during the reboot after install. Kudzu comes up and asks to install them.

Could it be that since it detects no interfaces during the install that is 
don't bither setting up nat and iptables correctly?

Getting frustrated and very pressed for time on this one!


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