| Virtual private network (VPN) is a special network created by a computer. |
 | | The computer which creates the VPN is generally on a local area network (LAN). In order to prevent IP address conflicts, LAN and VPN should have different IP address ranges.
To create the virtual private network:
1) The computer which is VPN server must allow VPN connections.
2) The computers which are VPN clients must have necessary programs to connect. |
| The client computers should not be necessarily on the same LAN. They can make connection to server computer over internet. The LANs in different locations can have same IP address range. For example, in the below picture, the IP address range of LAN1 and LAN2 can be same. |
| For internet connection, the TCP protocol 1723 and GRE protocol 47 of the router should allow for incoming and outgoing traffic (Firewall) and forwarded to the IP address of the VPN server computer (NAT). For example, if the IP address of the server computer is 192.168.1.101, router setting must be similar to one in below. |
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