To be able to run the LANdialler server you need a Unix box configured to do some sort of Network Address Translation (NAT) or IP Masquerading. You can use any modern Unix system, so long as it can run Python software. I use Linux, so I've included information on that here. You could use any of the BSD variants (e.g. FreeBSD, OpenBSD, NetBSD), Solaris, etc. instead if you prefer.
If it wasn't for the excellent documentation then setting it up would be quite a long and painful process for the uninitiated. First find out which version of the Linux kernel you are running (type uname -r) and then follow the relevant links below.
These are the scripts that I use to run iptables on a Linux
2.4 kernel. They provide both NAT and a firewall. If you want
to re-use these scripts just drop them in the
/etc/ppp/ip-up.d directory to have them
automatically run when dialling up. Once you've dialled up you
can check that they've run by running
#!/bin/sh # # $Id: routing-docs.html,v 1.4 2004/03/14 15:12:42 graham Exp $ # # Home firewall script, put together from commands in the NAT and # packet filtering HOWTO documents. # # Suitable for dropping into /etc/ppp/ip-up.d if you're running # Debian, to be automatically run by /usr/bin/pon after dial up. # Load the NAT module (this pulls in all the others). modprobe iptable_nat # insmod ip_conntrack (autoloaded by iptable_nat by the looks of it) insmod ip_conntrack_ftp # Clear all current rules, so we start from a clean slate. iptables -F # Create chain which blocks new connections, except if coming from inside. iptables -N block iptables -A block -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A block -m state --state NEW -i ! ppp0 -j ACCEPT iptables -A block -j DROP # Jump to that chain from INPUT and FORWARD chains. iptables -A INPUT -j block iptables -A FORWARD -j block # In the NAT table (-t nat), Append a rule (-A) after routing # (POSTROUTING) for all packets going out ppp0 (-o ppp0) which says to # MASQUERADE the connection (-j MASQUERADE). iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE # Turn on IP forwarding echo 1 > /proc/sys/net/ipv4/ip_forward
#!/bin/sh # # $Id: routing-docs.html,v 1.4 2004/03/14 15:12:42 graham Exp $ # # Home firewall stop script. # # Suitable for dropping into /etc/ppp/ip-down.d if you're running # Debian, to be automatically run by /usr/bin/pon after dial up. # Turn off IP forwarding echo 0 > /proc/sys/net/ipv4/ip_forward