Routing on Red Hat Linux 9

I am trying to set up a LAN consisting of a machine running Red Hat Linux 9
acting as a firewall and router and a Windows 2000 machine that I would like
to use to access the Internet from behind the firewall. The Linux machine
accesses the Internet correctly through the eth0 interface. The Windows
machine, however, cannot access the Internet; it can successfully ping the
IP address of the network card in the Linux machine it is connected to
(eth1) and the IP address of the eth0 card, but pinging our gateway fails.
The Linux machine can successfully ping both the Windows machine and the
gateway. Could someone please tell me what causes this problem and possibly
how to fix it? Thank you.

"Aleksandr Zingorenko" <(E-Mail Removed)> wrote:

> I am trying to set up a LAN consisting of a machine running Red Hat Linux
9
> acting as a firewall and router and a Windows 2000 machine that I would
like
> to use to access the Internet from behind the firewall. The Linux machine
> accesses the Internet correctly through the eth0 interface. The Windows
> machine, however, cannot access the Internet; it can successfully ping the
> IP address of the network card in the Linux machine it is connected to
> (eth1) and the IP address of the eth0 card, but pinging our gateway fails.
> The Linux machine can successfully ping both the Windows machine and the
> gateway. Could someone please tell me what causes this problem and
possibly
> how to fix it? Thank you.
>

To an extent, this depends on your setup. If you are using static IP's,
then you probably need to run the command :-

echo 1 > /proc/sys/net/ip_forward

To enable IP forwarding, then setup appropriate routing for your network.
If you are using a private IP range, then you need to setup IP Masquerading,
in which case, search google for 'IP masquerading howto' for more
information on how to set that up.

--

Martin

Do you have the IP address of the Linux eth1 specified as the gateway for
the Win2k box?

Some setup specifics would help, such as the output of 'ifconfig',
'route -n', and 'iptables -L -n' on the Linux box and 'ipconfig /all' from
the Win2k box.


"Aleksandr Zingorenko" <(E-Mail Removed)> wrote in message
news:beco94$pt7$(E-Mail Removed)...
> I am trying to set up a LAN consisting of a machine running Red Hat Linux
9
> acting as a firewall and router and a Windows 2000 machine that I would
like
> to use to access the Internet from behind the firewall. The Linux machine
> accesses the Internet correctly through the eth0 interface. The Windows
> machine, however, cannot access the Internet; it can successfully ping the
> IP address of the network card in the Linux machine it is connected to
> (eth1) and the IP address of the eth0 card, but pinging our gateway fails.
> The Linux machine can successfully ping both the Windows machine and the
> gateway. Could someone please tell me what causes this problem and
possibly
> how to fix it? Thank you.
>
>

Thank you very much for your advice - I now have a working Linux router.
However, I found out that after setting up IP Masquerading, as shown in the
Red Hat Linux 9 Bible, the Kernel IP routing table was set up wrong - it had
2 identical routes to the Windows machine via interface eth2, which at this
point is unconnected, even though the Windows machine is connected to the
router via eth1 and could connect to the Internet after a manually added a
single appropriate route. Did I do something wrong beforehand, or did I
encounter a (mis)feature of Red Hat Linux that must be manually corrected if
necessary?

"Martin Cooper" <(E-Mail Removed)> wrote in message
news:gemini.3f09f478014ebf21%(E-Mail Removed). ..
> "Aleksandr Zingorenko" <(E-Mail Removed)> wrote:
>
> > I am trying to set up a LAN consisting of a machine running Red Hat
Linux
> 9
> > acting as a firewall and router and a Windows 2000 machine that I would
> like
> > to use to access the Internet from behind the firewall. The Linux
machine
> > accesses the Internet correctly through the eth0 interface. The Windows
> > machine, however, cannot access the Internet; it can successfully ping
the
> > IP address of the network card in the Linux machine it is connected to
> > (eth1) and the IP address of the eth0 card, but pinging our gateway
fails.
> > The Linux machine can successfully ping both the Windows machine and the
> > gateway. Could someone please tell me what causes this problem and
> possibly
> > how to fix it? Thank you.
> >
>
> To an extent, this depends on your setup. If you are using static IP's,
> then you probably need to run the command :-
>
> echo 1 > /proc/sys/net/ip_forward
>
> To enable IP forwarding, then setup appropriate routing for your network.
> If you are using a private IP range, then you need to setup IP
Masquerading,
> in which case, search google for 'IP masquerading howto' for more
> information on how to set that up.
>
> --
>
> Martin