How do I make a TCP server work behind a router (NAT) without any redirection configuration needed.

Posted by Chetane on Stack Overflow See other posts from Stack Overflow or by Chetane
Published on 2009-10-02T20:10:32Z Indexed on 2010/05/01 21:37 UTC
Read the original article Hit count: 185

Filed under:

nat

|

p2p

|

tcpip

|

networking

The scenario is the following. I have two machines A and B: A: Client (behind NAT) B: Server (behind NAT)

I want B to be able to listen on any given port, so that A can send packets to B through that specific TCP port and receive any response. If both machines are not behind a NAT it is pretty straight foward process. However how do I make it work so that it works even when B is behind a router, without him having to go change the router configuration enable some port forwarding etc...

For example, how do p2p program like torrent clients work without the user having anything to configure?

Thanks and I hope my question is clear enough.

© Stack Overflow or respective owner

Related posts about nat

Cisco 881 losing NAT NVI translation config after reload

as seen on Server Fault - Search for 'Server Fault'
This is a weird one, so I'll try to explain in as much detail as I can so I'm giving the whole picture. As I've mentioned in my other questions, I'm in the process of setting up a new Cisco 881 as my WAN router and NAT firewall. I'm facing an issue where NAT NVI rules that I have configured are not… >>> More
IPtables AWS EC2 NAT/Reverse NAT - For Reverse Proxy style setup but with IPtables

as seen on Server Fault - Search for 'Server Fault'
I was thinking initially needing to do a reverse proxy or something so I could get some SSL/TLS traffic look like it is being terminated at a server and IP address in the AWS cloud, and then that traffic is forwarded onto our actual web servers that aren't in the cloud... I've not done much iptables… >>> More
asterisk/freeswitch in nat/no-nat setup

as seen on Server Fault - Search for 'Server Fault'
hi, my current setup - i use bunch of sip hard-phones around few offices. all devices have two sip accounts configured - one on internal sip proxy [for calls between the branches], another - at 3rd party voip providers [ since it's in different countries - those are different providers, but that's… >>> More
Problem with setup VPN in Ubuntu Server 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I have a problem with setup VPN server on my Ubuntu VPS, here is my server environments: Ubuntu Server 12.04 x86_64 xl2tpd 1.3.1+dfsg-1 pppd 2.4.5-5ubuntu1 openswan 1:2.6.38-1~precise1 After install software and configuration: ipsec verify Checking your system to see if IPsec got installed and… >>> More
Problem with setup VPN on Ubuntu Server 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I have a problem with setup VPN server on my Ubuntu VPS, here is my server environments: Ubuntu Server 12.04 x86_64 xl2tpd 1.3.1+dfsg-1 pppd 2.4.5-5ubuntu1 openswan 1:2.6.38-1~precise1 After install software and configuration: ipsec verify Checking your system to see if IPsec got installed and… >>> More

Related posts about p2p

Wifi Direct P2P-go and P2P-client support in ubuntu

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I am trying to get wifi direct working on a laptop with ubuntu 12.04 When I type the command 'iw list' it doesn't show P2P-client or P2P-go under 'supported interface modes.From http://wireless.kernel.org/en/users/Documentation/iw/replace-iwconfig I found that 'iwconfig' was replaced with 'iw'.Does… >>> More
.NET and P2P - writing a P2P messenger

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi there, Does anyone have any advice how to write such app? Or maybe knows some nice tutorial? I would like to use System.Net.PeerToPeer namespace, but everything I can find about it is MSDN which I can't read without getting mad. Or maybe using "old-school" TCP/IP would more efficient? I will… >>> More
Are there RTMFP tutorial for P2P video streaming ?

as seen on Stack Overflow - Search for 'Stack Overflow'
Are there RTMFP tutorial for P2P video streaming ? >>> More
Silverlight P2P App (In Browser) - Will we get RTMFP?

as seen on Stack Overflow - Search for 'Stack Overflow'
Ok so from all my research I'm fairly positive P2P is not possible in Silverlight 4 (in browser). Flash can do P2P using Stratus/RTMFP which I believe uses UDP hole punching and a Stratus server to help initialize the connection. Is there any plans for Microsoft to add some kind of p2p rendezvous… >>> More
Writing a P2P Snippet sharing Extension for Visual Studio 2010 (VSX 2010)

as seen on Code Project - Search for 'Code Project'
CodeXchange is a simple Visual Studio extension which allows you to create, edit and share snippets with your peers without leaving the Visual Studio 2010 IDE. >>> More