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Originally Posted by dnvikram
Thanx for the reply..
subnet mask is 255.255.255.0..I mustve typed it wrong here in the post..I tried with the correct mask only..I checked what all files I knew..so,can u kindly suggest what I may be doing wrong?
Thanks.
DNV
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use this iptables script
his is a how-to about sharing the internet via a linux box to the rest of your internal network.
In windows this is know as ICS (Internet Connection Sharing).
In linux it is called NAT (Network Address Translation).
1. On the linux box (that is directly connected to the internet, and is supposed to do the internet sharing), start a terminal. Run the command su and then type the root password to become root.
2. Open the file /etc/rc.d/rc.local in your favorite text editor and add this on a new line at the bottom
/etc/rc.d/rc.ipmasq and save the file.
3. Then, create a new file called rc.ipmasq in the /etc/rc.d/ directory and open this file in a text editor and add these lines
#!/bin/sh
IPTABLES=/sbin/iptables
#All The lines below are NAT routing
# flush any old rules
$IPTABLES -F -t nat
# turn on NAT (IP masquerading for outgoing packets)
$IPTABLES -A POSTROUTING -t nat -o eth0 -j MASQUERADE
# enable IP forwarding (of incoming packets)
echo 1 > /proc/sys/net/ipv4/ip_forward
Save this file.
This script assumes that eth0 is the ethernet adaptor connected to the internet (say, thru a DSL/cable modem). Change it depending on your configuration (eth1, eth2 and so on). If the connection to the internet is not thru an ethernet device (as in the case of ordinary dialup or USB modem), you have to use ppp0 (or ppp1, ppp2 and so on).
The network connections to the internet and intranet should already be up (how to do that is outside the scope of this document).
4. Make this script file executable by running chmod 755 /etc/rc.d/rc.ipmasq
5. Then run the command /etc/rc.d/rc.ipmasq to enable the internet sharing.
6. Now you can stop being root by running exit
The above script will work after the following have been already done:
Set up the network on all the computers in the LAN. Make sure every computer can be reached from another computer by "ping".
On each client computer, set the gateway to the internal IP address of the linux computer that is connected directly to the internet. Under DNS put in the primary and/or secondary DNS IP addresses of your ISP (Internet Service Provider).
