OpenVPN primer

There are as many advantages to VPN tunnels as there are different VPN scenarios. One easy implementation is the "OpenVPN via tun-device" solution. An example: you'd like to connect your laptop to your LAN at home so that you can use your mail client without reconfiguring it anytime you switch from home to internet and back.

Let's say your mail-server is 192.168.1.10 in your LAN (192.168.1.0/24) at home, and you have got a router/firewall providing access to the Internet. You connect from work or school and want to read mail. OpenVPN can create two virtual devices for you when connecting two computers through an encrypted tunnel.

Naturally you then have the possibility of forwarding traffic into the networks behind them, and thus would be "virtually connected" to your LAN behind the firewall. To enable this, either your firewall or a server behind it should run OpenVPN (if you choose a server in your LAN, you'll have to forward the destination port to the OpenVPN server).