OpenVPN

OpenVPN is a opensourse Software to establish virtual private network(VPN) via encrypted TLS connections. It provides a secure and encrypted user data communication between different hosts and networks.

• High compatibility and support for many Operation systems (Linux, OS X, Windows, iOS, and Android)
• High stability
• Easy Scalability
• Flexible VPN client extenions
• Easy installation

The following step by step instruction will guide you through a OpenVPN configuration. So basically OpenVPN does have two different modes:

Bridge mode (TAP):

Advantages

• behaves like a real network adapter (except it is a virtual network adapter)
• can transport any network protocols (IPv4, IPv6, Netalk, IPX, etc, etc)
• Works in layer 2, meaning Ethernet frames are passed over the VPN tunnel
• Can be used in bridges

Disadvantages

• causes much more broadcast overhead on the VPN tunnel
• adds the overhead of Ethernet headers on all packets transported over the VPN tunnel
• scales poorly

Routing Mode (TUN)

Advantages

• A lower traffic overhead, transports only traffic which is destined for the VPN client
• Transports only layer 3 IP packets

Disadvantages

• Broadcast traffic is not normally transported
• Can only transport IPv4 (OpenVPN 2.3 adds IPv6)
• Cannot be used in bridges

For this configuration we will use the most common mode, the routing mode.

See openvpn.pdf