DSL internet sharing

Forum: Networking
Topic: DSL internet sharing
started by: Alexalamode

Posted by Alexalamode on Jan. 20 2006,22:16

I am very new to Linux. I think this would be possible, but before I invest a lot of time in trying it, I thought I'd make sure by asking..

Here is my situation. I live out in the middle of nowhere, and must use a 56k modem. Because of the two people in the house, we have to used a shared modem.. Because of it being a modem, we need a computer online all the time running the network. Right now, it's my computer, and I'd rather have a dedicated computer to it, so I don't have to have mine running full time (Is rather loud).

Would it be possible to take an older computer (400 megahertz, 128 mb of ram. Definitely can run DSL) and use it to run a wireless network that will share the modem connect across multiple computers?

Thank you for your time.

Posted by cbagger01 on Jan. 22 2006,16:14

Anything is possible, provided:

1) Your ISP uses a standard PPP dialup instead of some custom MSWindows application.
2) Your modem is not a "winmodem" and is supported by DSL. One exception: Lucent-based winmodems are supported.
3) Your wireless adapter is supported by DSL and can work as an AP OR:
You buy a cheap wireless router that can run as an AP and a wired LAN card that works with Linux.
4) You learn how to do commandline network configuration, IE routing, for Linux. It is not point-and-click to do such things.

Posted by northface on Jan. 22 2006,22:16

I was thinking about your post as I was trying to set up my dial-up connection. I was looking around and found something that you might be able to use:

/etc/network/interfaces

in the file * if you open it up for editing using vi

there is a line

ip_forward= no

change to:

ip_forward=yes

then you will have to check out iptables.
I am not sure it runs by default. but you will definitely have to set up iptables to handle the traffic. The terminiology is different from ipchains. I dont know how so I cant help you there...but if you go to tldp.org and look up iptables there might be something there for you to get this going.

that is if your modem is supported in dsl.

I hope this helps.

NorthFace

Posted by Alexalamode on Jan. 23 2006,03:49

Ah, I see. Thanks both of you. I'll see what kind of modem it is.

Posted by skaos on Jan. 23 2006,11:20

I think you need something called a firewall or router. There are special linux distros for this, look for "Top 5 Firewalls" in this page
< http://distrowatch.com/dwres.php?resource=major. > I have never used any of these, so I have no idea if they're simple to set-up and use. What I know is that setting up a firewall from scratch is anything but simple, but if you're interested, take a look at: < http://linuxgazette.net/103/odonovan.html >

Posted by northface on Jan. 24 2006,03:44

IPCHAINS
This assumes that your external interface is called `ppp0'. Use ifconfig to find out, and adjust to taste.
# ipchains -P forward DENY
# ipchains -A forward -i ppp0 -j MASQ
# echo 1 > /proc/sys/net/ipv4/ip_forward

IPTABLES
< http://en.tldp.org/HOWTO....TRONGER >

that link will take you to a howto for IPTABLES

look for:

#CRITICAL: Enable IP forwarding since it is disabled by default since
#
# Redhat Users: you may try changing the options in
# /etc/sysconfig/network from:
#
# FORWARD_IPV4=false
# to
# FORWARD_IPV4=true
#
echo " Enabling forwarding.."
echo "1" > /proc/sys/net/ipv4/ip_forward

if you pay close attention to the directions its quite possible to turn linux into a router and firewall. you could buy one, or you could save money but not time and configure it manually.

"Without struggle there is no progress"
Frederick Douglas

Posted by AwPhuch on Jan. 24 2006,23:38

Why do all that?!?!?!

Just get the iptables.dsl and rc.firewall.dsl
< http://projectfiles.com/firewall/ >
< http://projectfiles.com/firewall/config.html >

Then if you are using "frugal" mode just edit the rc.local file...

It is a simple script, but is capable of doing tons upon tons of stuff..internet sharing, port forwarding, routing, you name it..with just a few simple script modifications you could make a small DSL machine into one hell of a powerful router/firewall...

or you could build you a < SmoothWall Express 2.0 > box

Brian
AwPhuch