[nSLUG] Need help seting up ICS in Redhat 9

Donald Teed dteed at artistic.ca
Tue Jul 15 22:56:18 ADT 2003

Writing the complete steps out for this task, covering every
possible step along the way (such as configuring your
network cards) is quite a task.  It could be a small
book if one wanted to write it for an audience that knew
absolutely nothing about Linux.  It would be easier if we
knew more about your set up, what works, what doesn't, and
some of the crucial config files.  If you simply don't have
the time to spend learning something about Linux and networking,
you should keep the router option open.  They are cheaper
than you might think.

Staples has a basic router (Dlink DI-604)
that would work for you for $60 and has a mail in $40
rebate that expires on Sunday.  (Cost of tax on 
$60 plus $20 = $29 in the end.)  This works fine
unless you plan to run a DNS server behind the
router, which seems unlikely.

Going the linux way...
You need to have these basic requirements met:

1. Network drivers loaded for each NIC in the redhat machine
2. Configuration of each NIC in the redhat machine (try 'neat')
   a.  Assign NIC attached to cable modem as a DHCP configuration
   b.  Assign NIC attached to hub with a static address such as
3. Configuration of DHCP server on Linux machine, or set up notebook with
   a static IP address for the home use
4. Configuration of iptables to do NAT (network address translation)
I doubt there is a script or a wizard that will do all of the above.
It will require acquiring knowledge about these things, so do
not expect it to progress like installation of a satellite
dish or McAfee Virus Scan.

You need to test the progress along the way:

1. Can your Redhat machine set and get the two IP addresses?
   Use ifconfig command to show the settings of eth0
   with 'ifconfig eth0', same can be done for eth1 .
2. Is the NIC attached to the cable modem getting an IP address?
   Can Redhat ping www.google.ca ?
3. Is the notebook able to get an IP address from the DHCP server on Redhat?
   Test with ipconfig /all   Can notebook ping Redhat and vice versa?
4. Finally, once iptables rules are configured with nat, can both
   the Redhat machine and the notebook machine see the internet?

If you run into difficulty, post back here with details on
what you've tried, what works and what doesn't work, and then
we will have an idea where to fill you in.

To start, check this manual from Redhat, and it will allow you to
set up your network and DHCP server.  It isn't very good
for instructions on iptables, but this can be tackled later.


See the sections on network configuration:


and then DHCP server set up:


These instructions are specific to Redhat 9 and should be quite
applicable.   They also include the benefit of using graphical
dialog boxes to set up fields rather than editing text files
(where available), which can be easier for a new linux user.

If you are completely new to linux, networking and such, don't
be surprised that it can take a few hours to days to get through
this.  If your time is more valuable, or patience wears thin,
that router box at Staples might be the way to go.

Depending on why you have the Redhat machine, you might
want to consider another Linux solution.  If this is
purely a router and you don't do much else on Linux,
you could try one of the many Linux Router mini-distrbutions out
there.  Some of them will set up a router with DHCP and iptables
with a run of a simple install wizard.

--Donald Teed

On Tue, 15 Jul 2003, Michelle and George wrote:

> I'm having a hell of a time trying to get my redhat workstation to share
> it's cable connection with my wifes (acadia u) winxp laptop. She needs
> access from home and I have searched the web for days in vain. I am a
> complete newbie- the documentation out there is WAY over me little head
> and I'm about to scream!! I have two nics in the redhat box, and a wee
> hub. Before you say it, no, I can't go out and buy a router right now.
> Any help you can throw my way would be great.
> George Vincent-Cross
> _______________________________________________
> nSLUG mailing list
> nSLUG at nslug.ns.ca
> http://nslug.ns.ca/cgi-bin/mailman/listinfo/nslug

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