setting up centos to act as a router / bridge

the2k · 11-13-2012, 05:38 PM

Hi there

I am having problems setting Centos to act as a bridge between my wired LAN and the wireless internet connection. Where I have my LAN I can't get any wireless signal to get access to the internet. The only machine that can get wireless access is my newly acquired server.

so currently I have 1 machine and a server on a wired connection (soon to add another machine) and the server has a wireless connection to the outside world.

I am hoping that this problem is reasonably simple, I've had a very long day at work, and my knowledge of Linux networking is poor at best!

so far from what I have read online is to...

Code:

echo 1 > /proc/sys/net/ipv4/ip_forward

then

Code:

iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

however when I go to the workstation and try pinging 173.194.67.99 (google) I get the following error

Code:

From 192.x.x.x icmp_seq=1 Dest Unreachable, Bad Code: 10

Now I think this could be an issue with iptables, but I have no idea what or how to fix it. To be fair I might be completely wrong with this and i'm barking up the wrong tree altogether!

If anyone has any idea's about how to solve this please say, then I get on with trying to sort out the nameserver issue.

I don't know if it is relevant but the server is running Centos 6.3 my workstation is running Suse 12.2 and the other machine isn't connected to the network yet!

the2k · 11-13-2012, 06:12 PM

Hmmm,

Now I'm completely confused. when I set up eth0 as a trusted interface in the firewall configuration program or turn iptables off I just get 100% packet loss, this is beginning to get really confusing.

custangro · 11-13-2012, 06:22 PM

This is how I've always done it...

vi /etc/sysctl.conf and edit the following

Code:

 net.ipv4.ip_forward = 1

Now sync it with sysctl

Code:

sysctl -p

Restart networking

Code:

service network restart

Next set up your iptables like so...

Code:

service iptables stop
iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
service iptables save
service iptables restart

the2k · 11-16-2012, 03:22 PM

Sorry for the late reply, I had to dash to London for a couple of days business

Cheers for your help!

now to get the nameserver working

the2k · 11-16-2012, 03:37 PM

bizarre, it seems to have started working! its incredibly slow, but at least it seems to work... maybe I need a gigabit switch?

edit... I don't think the switch is at fault, I need to investigate this further, but it shouldn't be this slow...

cheers for your help so far

Mike