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How to open ports on your router

By ragne2
Nov 30, 2010
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  1. I was wondering on how to open ports so i can run a server and be a host.
    Can u please give me a simple guide on how to open ports on your router.
    OR:
    Is there any programs that can actually open ports on ur router for you?
    cause im too lazy to do all that command promt stuff. but if using command prompt is the only wy ill do it.

    Can u also teach me how to forward those ports to your router so that outside sources can access them.
     
  2. jobeard

    jobeard TS Ambassador Posts: 13,450   +324

    Opening a port is a goofy term - - let's start with just using a port.
    For a port to exist, some program creates a socket and then uses it to LISTEN for connections. You can see this with (command prompt tool) netstat -oan
    Programs which are awaiting connections show up like
    Code:
      TCP    0.0.0.0:[B]135            [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]445            [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]1030           [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]3389           [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]4186           [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]8019           [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]44334          [/B]0.0.0.0:0              LISTENING
      TCP    0.0.0.0:[B]44501          [/B]0.0.0.0:0              LISTENING 
    the nnn are the 'port numbers' created by the program.

    Q? Which ports are open? A: only those that exist, eg: port 135 is open, and port 136 is closed (ie doesn't exist).
    Regardless of your other setups for the router and firewall, the port is not open unless a program is LISTENING.

    HOWEVER, that's only one-third of the story; two other conditions must be met
    1. the firewall on that system must be configured to ALLOW traffic to the specific port(s) desired
    2. and, if a system not on your LAN needs access to a program on that system, then
      the router must port forward
    Consider this network
    Code:
    ISP==modem/router 
                   |
                   + ------- System A
                   |
                   +-------- System B
    
    if System A has the program (and the port is listening and the firewall allows)
    then System B can get to it without concern for the router at all.[*]

    Now if your friend in New York wants to connect to System A located in Los Angeles,
    then the router must port foward.

    Port Forwarding requires that the server address never change,
    so first you need to arrange to have System A use a static IP address on your router.
    Once that's correct, then, using the documentation for the program on system A, you add a port forward like
    forward port xxx to IPaddress-for-systemA​

    SO; get [*] to work first and then deal with the router
     


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