Router Port forwarding/port triggering WHAT DO THEY DO?

Discussion in 'Computer Support' started by ToyalP2, Dec 29, 2007.

  1. ToyalP2

    ToyalP2 Guest

    I have a netgear router and I can't have my webcam get through to FTP to
    my server. Webcam32 FTP works if I connect the PC directly to the cable
    modem but when I put the router in the chain it won't work.
    I believe it may have something to do with Port Forwarding and/or
    Triggering but I have no idea how do they work or how to set them up. I
    get confused by ports and IPs.
    I have fiddled with PF and PT to no avail.
    Thanks for any help.
    ToyalP2, Dec 29, 2007
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  2. ToyalP2

    Mr. Arnold Guest

    There are two types of traffic a router or a firewall deals with on inbound
    traffic. There are unsolicited and solicited inbound traffic.

    Solicited traffic is any inbound traffic from a remote IP that a program
    running on a computer behind the router or a firewall that has sent outbound
    traffic to the remote IP. That's a solicitation for inbound traffic, and the
    router or firewall will allow that traffic to pass through them back to the
    computer that made the solicitation.

    Unsolicited inbound traffic is any traffic inbound that was not solicited by
    a computer running a program behind the router or firewall, and that traffic
    is blocked by them.

    As an example, you have a Web server running on a computer behind the router
    or firewall, like IIS or Apache. Those are server applications, and a Web
    server has a client such as a browser, which the traffic is being
    transmitted over the Internet, and it's HTTP on TCP port 80. IIS or Apache
    never make the initial contact with a client application. There is no
    outbound traffic (the solicitation) that has been sent.

    It's the browser that must initiate the contact with the Web server. But
    that's unsolicited inbound traffic. Well, that's where Port Forwarding comes
    into play. Port Forwarding allows unsolicited inbound traffic to come in on
    a port past the router or firewall, which would be TCP port 80. All
    unsolicited inbound traffic that's on port 80 from a client application,
    like a browser, that needs to make the initial contact with the Web server
    is Port Forwarded on TCP port 80 to the LAN/IP/computer that has the Web
    server running. Only a single LAN/IP/computer can use Port Forwarding. No
    other IP on the LAN can have Port Forwarding in your case.

    IIS and Apache are just one example. There are other such programs that can
    run on your computer that can be a server application where the client
    application must initiate the contact with the server with unsolicited
    inbound traffic that would be blocked by the router or FW unless Port
    Forwarding is used.

    Port Triggering is a form of Port Forwarding. However, Port Triggering
    allows multiple LAN IP(s) to accept inbound traffic. As an example, you have
    5 people running a client game program on the computers, and the inbound
    TCP port being used for the game is port 10,000. There is the game server
    sitting out there somewhere and everyone is playing the game with the game
    server from behind your router. This is when Port Triggering will come into
    play on the router. Port Triggering on the router knows where to send the
    inbound traffic to the LAN/IP(s)/computers on port 10,000 that are playing
    the game with the game server application running on a computer that's on
    the Internet.
    Mr. Arnold, Dec 29, 2007
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  3. We don't know anything about your network topology.
    Is the server your PC or a webserver at a hosters location?
    Then, the webcam, does it sit on your monitor or is it elsewhere
    wisdomkiller & pain, Dec 29, 2007
  4. ToyalP2

    why? Guest

    If you know the model of the router try,
    What they do on a netgear router
    A port (channel/frequency) is a service something sends / listens on.
    list of ports,
    see (2)

    An IP address is a source / destination for connecting between.
    Fiddle, oh well. Have fun.
    why?, Dec 29, 2007
  5. ToyalP2

    Dan C Guest

    Dan C, Dec 29, 2007
  6. ToyalP2

    ToyalP2 Guest

    Well Mr. Arnold, first thank you for your reply, I have been to and I still don't understand but maybe what I want to do
    won't fall into that category:
    System is XPPro 3GHZ 1GB. NO firewall.
    I have installed Webcam32 and I have a Logitech QuickCam.
    I was able to have friends see my webcam LIVE with Javacam before
    installing the router, a Netgear WGT624.
    I was also able to use webcam32 to FTP an image (.jpg) to my web host at
    an set interval but of course that's not LIVE but it takes a few seconds
    and the image is just a sequence of .jpg images that could be see by
    accessing my <---- this is not a real link.
    I can do both things by taking the router out of the picture but not
    with it connected.
    Javacam will require the external viewer over the Internet to get to my
    computer and retrieve the address for the javacam for a live display. I
    guess this is where Port Forwarding is supposed to work, right?
    With the Webcam32 FTPing images to my web host I need to set the router
    to allow webcam32 to pass through as I can simply do when I upload files
    with Bulletproof FTP. However Webcam can't get passed the router.
    I don't know how to setup the router to do either one although I would
    obviously prefer to have Java cam working.
    In other words, I need to GO OUT with images to my FTP/web host and/or
    let others to COME IN to my PC to retrieve the necessary info for
    I don't know if this will explain the 2 situations better:

    Webcam32 sending FTP images to my domain (webhost)
    MyPC >>>>>>>Router>>>>>>>MyWebhost

    Javacam (live)
    MyPC<<<<<<<Router<<<<<<<Remote Viewer accessing my PC for the address of
    the cam.
    MyPC>>>>>>>Router>>>>>>>Replying with the address to the remote viewer.

    I hope this shines more light into the subject and forgive me if my
    English is not as good. I speak other 2 languages and English is not my
    ToyalP2, Dec 30, 2007
  7. ToyalP2

    Mr. Arnold Guest

    Your solutions behind the router the server applications, and the router
    itself are not the problem. They do not have any problems with sending
    outbound traffic through the router, once contact has been made initially
    with them by the client application running on a computer over the Internet
    from the client's remote/IP/computer running the client application.

    Like what was stated before, it is the client side application that must
    initiate the contact with the server application and to the computer behind
    your router that is running the server application.

    Let's get this straight as to what is meant by client/server. I am a
    customer in a restaurant, and I want some food (I am the client). I tell the
    waiter that I want to order, and the waiter (the server) servers me the
    ood -- the client/server relationship.

    The router is not in the picture at this point. And me the client/customer
    can order food from the server/waiter all day long, and the server will
    server me. The waiter (the server) can hear my orders for food, because
    there is nothing in the way that is preventing the (waiter/server) from
    hearing my orders (the client/customer), and the (waiter/server) will server
    me the (client).

    Now the router comes into play. The router is a very big and thick wall, and
    the wall has many doors that are closed. I the (customer/client) holler out
    to the (waiter/server) for an order, but the (waiter/server) cannot hear me
    (the customer/client) in this situation, because the wall is there blocking
    the sound from me. The (waiter/server) can't hear me. I the
    (client/customer) cannot make a solicitation to the (waiter/server) to have
    my orders served to me.

    But wait, there are doors (ports) on the wall, if the correct door (port) is
    opened and it remains open all of the time, then the (waiter/server) will
    hear me with my orders. The (waiter/server) doesn't know that the
    (doors/ports) are closed on the wall. In addition to this, I the
    (customer/client) need to use a particular (door/port) or it could be
    particular (doors/ports) on the wall so the (waiter/server) can hear me.

    There is a (wall/router) master (an administrator) and that's (you), and he
    knows what (door/port) or (doors/ports) must be opened on the
    (wall/router), and they must remain open at all times for me or other
    (customers/clients), in order for any of us to make that first/initial
    contact with the (waiter/server). Once the initial contact with the
    (waiter/server) has been made, then the (waiter/server) knows we are there,
    and the (wall/router) knows we are there, and it's free flow communications
    between us (the customers/clients) and the (waiter/server) and the
    (wall/router) is controlling the communications, once the first/initial
    contact has been made with the (waiter/server).

    The (wall/router) master (the administrator) (you) knows to use Port
    Forwarding on the (wall/router), and he knows what inbound (doors/ports) on
    the (wall/router) that must be opened at all times so that the
    (waiter/server) can hear its potential (customers/clients) making the
    first/initial contact for orders.

    The bottom line here is that you must know what port/ports must be opened
    and Port Forwarded to the LAN/IP/computer that has the server running so
    that the clients can make the initial contact with the server. Who ever is
    viewing the pictures from the Web cam is the client, and the Web cam is the

    If you don't know what the inbound port or ports the Web cam server is
    listening on, then you must find that out by either using Google to find out
    the ports that the Web cam is listening on, or you use something like Active
    Ports (free) install it on the computer, you start it up, start the Web cam
    server application up, and Active Ports will show you what port or ports the
    Web cam application is listening on for the inbound traffic.

    However, the router that you are using may not work with the Web cam
    application too, and you need to find that out.

    The other choice you have is to put the computer into the DMZ of the router,
    so that basically, the router is not protecting the computer, blocking the
    ports. It as if the router in not there when the computer in exposed to the
    Internet using the router's DMZ. I suggest that you use a personal firewall
    on the computer, close all ports on the personal firewall, and only open the
    inbound ports or ports the Web cam application needs open so that the
    clients can make the first initial contact, otherwise, the computer is wide
    open to attack.

    The computer was wide open to attack when you connected the computer to the
    modem, without the router being there and the computer had no personal
    firewall -- wide open to attack. And it doesn't take a computer long at all
    to be attacked when it's running the Windows O/S with no protection exposed
    to the Internet.

    Take the computer out of the router's DMZ if you put the computer there,
    and/or, make sure you close the ports on the router when you are done with
    the Web cam stuff.
    Mr. Arnold, Dec 30, 2007
  8. ToyalP2

    ToyalP2 Guest

    Mr Arnold, you are something else, to take the time to make such a
    lengthy explanation of Port Triggering/Forwarding is very special
    Considering the number people that use and read this newsgroup you are
    simple one in a million.
    When I have a problem that I can't resolve I usually post it here and
    the best and more precise replies have been usually from Mike and now I
    have to add you to my very short list of great guys!
    I read and very much enjoy your analogies and I will make a hard copy of
    your explanation and carefully read it off line to understand it better.
    Thanks you very much from the bottom of my heart and I wish you a very
    great year 2008.
    ToyalP2, Jan 7, 2008
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