Share internet connection

Braynid · 05-26-2006, 01:49 PM

Hello,
I relize that this topic has been discussed over and over again, and i to have read manny posts of this sort but it seems that i cannot have it done.
I have tried usig iptables but it won't work
I have Ubuntu on a computer, and another WinXP. eth2 is my internet and eth1 is my lan.
Could you pease teach me how to do this other than settup squid?
Thanks for your understanding.

acid_kewpie · 05-26-2006, 01:52 PM

tell us what you've actually tried and what did and didn't work. ultimately you MUST use iptables to do this, so you must have just missed a step out. you might like to use a gui tool like firestarter to configure it for you.

Braynid · 05-26-2006, 02:18 PM

I do not have firestarter or anything of the sort

apt-get install firestarter
Reading package lists... Done
Building dependency tree... Done
E: Couldn't find package firestarter

I have tried:
# iptables --flush
# iptables --table nat --flush
# iptables --delete-chain
# iptables --table nat --delete-chain
# iptables --table nat --append POSTROUTING --out-interface eth2 -j MASQUERADE
# iptables --append FORWARD --in-interface eth1 -j ACCEPT
# echo 1 > /proc/sys/net/ipv4/ip_forward

I work as root.The above are commands that I try from a HOW-TO, I have tried to follow the one on this forum but i get

apt-get install dnsmasq ipmasq
Reading package lists... Done
Building dependency tree... Done
E: Couldn't find package dnsmasq

Thank you for the quick reply!

Braynid · 05-26-2006, 02:20 PM

P.S: On the other computer i have: IP: 192.168.0.10 // MASK: 255.255.255.0 // GW: My ISP provided GW // DNS: My ISP DNS.
I use a cable modem.

Braynid · 05-26-2006, 03:22 PM

It seems that now I have broke it completely... i don't know how but now there is no ping reply between the two computers...
Any suggestions will be highly appreciated

Brian1 · 05-26-2006, 03:41 PM

To build an easy quick firewall router setup. Goto http://easyfwgen.morizot.net/gen/ and answer the questions it ask. Then it will build a script that you just need to cut and paste to a file and run. Also when you mean eth2 and eth1 do you mean eth0 and eth1 or does it have three nics installed. For me I perfer to make eth0 the wan internet side and use the rest as lan, dmz, other other network configurations.

Brian1

manishsingh4u · 05-26-2006, 04:06 PM

Run these commands on Linux (as root) or prefix "sudo " to these commands

Code:

iptables -P FORWARD ACCEPT
iptables -t nat -A POSTROUTING -o eth2 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward

Yout /etc/network/interfaces should look like this

Code:

auto lo
iface lo inet loopback
address 127.0.0.1
netmask 255.0.0.0
mapping hotplug
        script grep
        map eth2
iface eth2 inet dhcp
iface eth1 inet static
address 192.168.0.1
netmask 255.255.255.0
auto eth2
auto eth1

And your /etc/resolv.conf should have your dns entries

Code:

search somedomain.com
nameserver X.X.X.x
nameserver x.x.x.x

Replace somedomain.com with your isp's domain and "x.x.x.x" with your isp's dns ipaddresses.

Now, your windows XP machine must have configuration similar to this
ipaddress = 192.168.0.x
subnet mask = 255.255.255.0
default gateway = 192.168.0.1 (hint - linux eth1)
primary dns = your first dns (hint -used in /etc/resolv.conf on linux machine)
secondary dns = your second dns

If all this is correct and u have proper cabling, etc. Your internet connection sharing must work for sure. (I have this configuration...and it works).

Braynid · 05-26-2006, 04:43 PM

Dude you saved me. Now it's working!!!! Only one problem.. now i cannot access web-sites from the linux machine. It has ping reply only it does not resolve DNS correctly. I'll handle that tomorrow.
Many thanks to you, finally it's working.

manishsingh4u · 05-26-2006, 04:55 PM

Good Luck.

Braynid · 05-27-2006, 06:24 AM

I know it sounds lame, but how can i make a script that runs the commands on boot?

manishsingh4u · 05-27-2006, 12:25 PM

Quote:

how can i make a script that runs the commands on boot?

1) just write the commands of your choice line by line in any text file and save it by any name of your choice (eg. sinternet)
2) copy this file to your /etc/init.d/ directory

Code:

sudo cp sinternet /etc/init.d/ -v

3) Make this file executable

Code:

sudo chmod 0755 /etc/init.d/sinternet

4) Add this script to your default runlevel to start automatically, the default runlevel is ubuntu is 2. (Don't forget to type the dot at the end of the command)

Code:

sudo update-rc.d sinternet start 99 2 .

And there you are done.

Braynid · 05-27-2006, 02:21 PM

I thank you verry much for the help given. You have been most kind to a noob like me. B Good.

manishsingh4u · 05-27-2006, 03:10 PM

Quote:

Originally Posted by Braynid

I thank you verry much for the help given. You have been most kind to a noob like me. B Good.

It's your kindness. Some day, I was a noob too.