Port Forwarding for Beginners

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Port Fowarding By : ComputerShack

Title: Port Forwarding URL: http://www.computershack.net/content.php'article.74 Description: An intermediate users guide to Port Forwarding. Written by www.computershack.net


Port Forwarding

(Skill Level: Intermediate)


Terms: IP address (IP for short) - A numbering system for networked computers (ex 255.255.255.0) TCP - type of connection, to one other computers or IP UDP - type of connection, broadcast to multiple computers or IPs Port - A communications opening on your computer to the internet Port Scanner - Utility that checks for open ports on a networked item


This Article will give you a well rounded understanding of Port Forwarding. The following guide will give you a complete walkthrough of port forwarding on a linksys router (used by most). If you do not have a Linksys Router, Computer Shack recommends to all its customers this brand for Securitry, Reliability, Compatibility, and the advanced options and settings available on Linksys routers. There will be links at the bottom of where to find instructions for other brands of routers also.

For those who do not know what port forwarding is, it's the act of taking all information coming in to your network on a specific port, and directing it straight to a computer or device on the network. This would allow a computer inside your network, which is normally blocked to the outside world by your router, to appear like it was outside your network. This allows you to maintain security from the router on whatever ports you do not forward. You get to be safe (except the ports you forward), while still accessing the internet fully.

linksys Linksys Website


Reasons for Port Forwarding:

  • Packets not reaching your computer due to firewalls or router problems
  • Bit Torrent, or p2p file sharing programs will not work for you
  • allowing packets on specific ports to be forwarded to one ip or computer


Limitations of port forwarding:

  • Originating IP in TCP header is from your router when enabled, not an external ip
  • Your ping increases a few percent due to the router having to make new TCP headers, in order for your computer to know how to respond properly
  • Your IP is open to the public on the ports you forward


Common Port Numbers:

Service

Associated Port: Bit Torrent

6881-6889 FTP

21 SMTP

25 HTTP

80 HTTPS

443 DNS

53 POP3

110 SSH

22 Steam (Counter Strike, etc)

27015

Note: In many programs the port number you use can be changed


Helpful Links:

Linksys Website - Research products, upgrade firmware, and learn more about network security Netgear Support - The place to find these instructions for netgear routers D-Link Support - The place to find these instructions for D-Link routers


Disclaimer:

Port Forwarding opens your computer to the public on those ports. Computer Shack cannot be held responsible for which ports you forward which may or may not lead to a security threat.

Coming Soon: Instructions for Linksys routers port forwarding

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