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I'm new to VPN so please bear with me if I do any mistake. Earlier I also posted this question but no luck.

What I know: How to create a VPN connection on the client.

What I want: In order to access the server I need its IP address but since I'm accessing the company's server, the IP address of the server is not public, but private. The ISP has given five set of public IP addresses to the company, but I don't know how to give that public IP address to the server or any other peer connected to the server. It's a small firm so the server does not have any DNS on the Internet.

Please give me some suggestions. If possible give me some videos as well giving a complete description of the process. You can also suggest me some books but only on Windows setup and not for Linux. In some books I have also studied OpenVPN and closeVPN, what is it?

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up vote 3 down vote accepted

You need to reconfigure your router to forward ports from public IP addresses to the server private IP address.

Traffic goes: Internet public IP address (one of five IP addresses the ISP provided you) -> router -> server (private IP address).

Depending on your needs, you need to forward the following ports from the public IP address to the server private IP address on the router side:

PPTP VPN uses TCP Port 1723

IP Protocol 47 (GRE)

L2TP: UDP Port 1701

IPSec: UDP Port 500

Pass IP protocol 50 and 51.

Note: 47 is a protocol number and not a TCP port. The protocol name is GRE. The Generic Route Encapsulation (GRE) protocol is used in conjunction with Point-to-Point Tunneling Protocol (PPTP) to create virtual private networks (VPNs) between clients or between clients and servers. It'll make a big difference when configuring your firewall or router.

Note: On the client side, when you configure the VPN client, you need to use the public IP address.

Note: If you have a web based configured router (Linksys, Netgear, Firebox, SonicWALL, etc.) it's pretty simple.

But if you have a Cisco (PIX series or similar) it is a different story. You can configure cisco using the console COM port configuration or a Cisco web based manager. And on the client side use Cisco VPN client to connect.


What kind of router do you have?

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ok let me make it more clear.. – sumit Sep 7 '10 at 10:58
we have a linksys router and a switch.through the switch all the computers are connected through LAN and they have been assigned private IPs. – sumit Sep 7 '10 at 11:01
Ok, what kind of linksys model? Do you have linksys router on other end too? – S.T.A.L.K.E.R. Sep 7 '10 at 18:04
I m sorry its not linksys router It is WRT354 NETGEAR router. – sumit Sep 7 '10 at 19:50
as you told me that i need to forward the ports from public ip to can i do server is connected to switch only which in turn is connected to the netgear router. – sumit Sep 7 '10 at 19:52

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