A virtual private network (VPN) is a private computer network that interconnects remote (and often geographically separate) networks through primarily public communication infrastructures such as the Internet. VPNs provide security through tunneling protocols and security procedures such as encryption. For example, a VPN could be used to securely connect the branch offices of an organization to a head office network through the public Internet. A VPN can also be used to interconnect two similar networks over a dissimilar middle network; for example, two IPv6 networks over an IPv4 network.
VPN systems can be classified by:
- the protocols used to tunnel the traffic
- the tunnel’s termination point, i.e., customer edge or network-provider edge
- whether they offer site-to-site or remote-access connectivity
- the levels of security provided
- the OSI layer they present to the connecting network, such as Layer 2 circuits or Layer 3 network connectivity
There are mainly four protocols of VPN
1) Pure Ipsec
2) Ipsec with L2tp
3) ssl Vpn
Soon i will post howto setup all of above on Your Linux System and howto establish tunnel
using this protocol and howto securely communicate..