Internet Connection Sharing Problem

[garysteinert]

I have googled this to death, followed countless tutorials and not had any joy, so here goes:

I am trying to set up a router to provide internet access (among other things, just getting the internet to work for now) to a number of desktops and laptops.

I have followed a number of different tutorials, all of which seem to insist I need to:

• Set up a DHCP server
• Create firewall rules
• Some say I need to install ipmasq and dnsmasq

I have set up a working DHCP server.

/etc/dhcp3/dhcpd.conf

ddns-update-style none;

default-lease-time 600;
max-lease-time 7200;
log-facility local7;

subnet 192.168.1.0 netmask 255.255.255.0 {
	authoritative;
	range 192.168.1.0 192.168.1.254;
	option routers 192.168.1.1;
	option domain-name-servers 192.168.2.1;
	}

I have also set up the firewall rules:

/etc/iptables.up.rules

# Generated by iptables-save v1.3.8 on Wed May  7 15:48:06 2008
*nat
:OUTPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -o wlan0 -j MASQUERADE
COMMIT
# Completed on Wed May  7 15:48:06 2008
# Generated by iptables-save v1.3.8 on Wed May  7 15:48:06 2008
*mangle
:PREROUTING ACCEPT [102:15465]
:INPUT ACCEPT [99:15345]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [75:11388]
:POSTROUTING ACCEPT [83:12602]
COMMIT
# Completed on Wed May  7 15:48:06 2008
# Generated by iptables-save v1.3.8 on Wed May  7 15:48:06 2008
*filter
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
# Internal Network
-A INPUT -i eth0 -j ACCEPT
# Local Loopback
-A INPUT -i lo -j ACCEPT
# Existing connections
-A INPUT -m state -i wlan0 --state ESTABLISHED,RELATED -j ACCEPT
COMMIT
# Completed on Wed May  7 15:48:06 2008

The only line in that that does anything at the moment should be:

-A POSTROUTING -o wlan0 -j MASQUERADE

I have been using webmin to set these services up, so there should be no problem with the config files.

The problem:
The laptop I am using cannot connect to the internet

Connections:
Internet
-->
Virgin Cable Modem
-->
Belkin Wireless Router (basic config)
192.168.2.1
--> (Wireless)
192.168.2.2 (DHCP) (wlan0)
Ubuntu 8.04 Server
192.168.1.1 (eth0)
--> (Wired)
192.168.1.254 (DHCP) (eth0)
Laptop

The situation:

• Server and laptop both running Ubuntu 8.04 fully updated
• Laptop can reach wireless router through server (192.168.2.1)
• Server can reach the internet
• Laptop cannot reach internet (no ping, or web browsing)

I currently do not have ipmasq or dnsmasq installed because when I do install them, the server can no longer browse the internet or the router.

Also, I have checked IP forwarding and it is enabled.

Hope this is enough information for someone to see what I'm doing wrong.

Thanks

Gary

[athlon_crazy]

What nameserver your laptop currently use?

[garysteinert]

It uses 192.168.2.1. But either way, I thought the DHCP server assigned that?

Thanks

Gary

[athlon_crazy]

Yes but probably the server prevent your laptop talking to DNS services port 53. Try open this tcp udp port first..

[secondmouse]

Gary,
got a few questions:

1. How is your laptop connected to the desktop? Is it through a crossover cat5 cable, or a switch or else?
2. Can your laptop ping the Internet through IP? For example, 64.233.167.99 (one of google's IPs)
3. I know you mentioned ip forwarding in your post but I would like to know how you determined that ip forwarding is enabled.