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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.
The focus on OpenVPN is on
How to setup OpenVPN
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
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
See openvpn.pdf