Linux Firewall/Proxy/ ???

[Erates]

Hello,

So to begin, we are going to have a LAN party (just with some friends) on doomsday (21 december). So the plan is, that i install a Server (wich i have) between the modem and the router. (Yes the server has 2 network ports)

Now i want to block all internet connection from a certain time. I just don't know how to do it.

Any help?

Erates

[Lazydog]

You could read up on what rules do and how to use them with this TUTORIAL

Here is a very simple setup that will allow all connections out and only established connection back in.

iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
iptables -A INPUT -i <inside> -m conntrack --ctstate NEW,RELATED,ESTABLISHED-j ACCEPT
iptables -A OUTPUT -o <inside> -m conntrack --ctstate NEW,RELATED,ESTABLISHED-j ACCEPT
iptables -A FORWARD -i <inside> -m conntrack --ctstate NEW,RELATED,ESTABLISHED-j ACCEPT
iptables -A FORWARD -i <outside> -m conntrack --ctstate RELATED,ESTABLISHED-j ACCEPT

You will need to replace the <inside> and <outside> with your interfaces that are connected to the inside and outside.

What the above does is allow you to log into the server from the LAN only.
Traffic will pass from the LAN to the WAN and only established connection will be allowed to pass from the WAN to the LAN