This page explains how to set up a network for RuCTFE 2012. Here is step-by-step guide for Ubuntu 12.04.
Public NIC - eth0;
Private NIC - eth1;
Your team network is 10.23.N.0/24, where N is your team number.
Install Ubuntu 12.04 Server.
Configure your network in /etc/network/interfaces.
iface lo inet loopback
iface eth0 inet static
address 126.96.36.199 # your public ip
netmask 255.255.255.0 # your netmask
gateway 188.8.131.52 # your gateway
iface eth1 inet static
sudo apt-get install openvpn
Unpack OpenVPN config (should be in your POC's mailbox).
tar xzf teamN.tar.gz
Copy your private key to teamN directory (which has been extracted from archive), rename it to teamN.key and run
Now you should have your VPN up and running. Ping 10.23.0.1 to check it. Note: once OpenVPN connection is established, it can take up to 1 minute before pings will actually fly. If you experience longer delays, feel free to contact us.
Uncomment #net.ipv4.ip_forward=1 line in your /etc/sysctl.conf and then run sysctl -p
Set up NAT for the networks outside VPN.
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
Put this line to /etc/rc.local to run it automatically during boot.
Set the IP of each team's workstation taking out one from 10.23.N.0/24 pool.
Set the 10.23.N.1 as a gateway on each workstation.
Set the virtual machines NICs bridged to the NIC of the machine hosting the VM.