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Manually open ports (star topology)

Discussion in 'Networking' started by renegade X, Feb 8, 2005.

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  1. renegade X

    renegade X Thread Starter

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    Hello all. My home network uses a switch and I want to use some remote software to access my Home PC from Work. I am not firewalled, but it seems that all of my ports are closed, due to the switch. Is there anyway to manually open ports.
     
  2. Monstrous Mi

    Monstrous Mi

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    You have to go into the configuration of the switch and allow port forwarding. Thus, when a port request comes from the outside, the switch will know which internal host to forward the request to.

    BTW, this is very dangerous if you are accessing your home PC from the Internet. People are constantly scanning the Internet looking for open ports and they will find yours very quickly and begin trying to access whatever you have opened.

    Maybe you describe what exactly you need to access your home PC for and then somebody can describe a much safer way to it.
     
  3. renegade X

    renegade X Thread Starter

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    Thanks for the concern, but on my PC, I really would not care if someone went into it, if they get pass the password. I bypassed my switch, but still can't get in. I can access through the program PC 2 PC on my home network. What am I missing?
     
  4. angel

    angel

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    Have you checked with your ISP to see if they are blocking the ports there?
    Some ISP's do not allow running servers of any kind (game, http, ftp, etc) and actively take steps to not allow it. (My old ISP used to block ALL incoming traffic unless the request was initiated from my side.)
     
  5. renegade X

    renegade X Thread Starter

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    My co-wotker uses the same program with the same ISP with no problems. I bypassed my switch and still can not get in. I think I may be able to force a port in my cable modem, do you think so?
     
  6. Monstrous Mi

    Monstrous Mi

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    I don't understand what you mean by "bypassing the switch"? I've never heard of a modem which is concerned with ports.

    BTW, to see if you are actually getting to your PC, you can use the telnet command.

    At a command prompt: e.g.
    C:/windows/system32/telnet <IP Address> <Port Number>

    If you get a connection, then you have a settings problem in your software. If you don't get a connection, then the suggestions of myself and renegade X still apply.
     
  7. squidboy

    squidboy

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    A pure 'switch' will not block traffic, just create different virtual paths to each host. It really depends on the brand of switch you have. Some have routing capabilities. It would be helpful if you specified which brand/model 'switch' you have.
     
  8. JohnWill

    JohnWill Retired Moderator

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    I'm guessing the "switch" is really a broadband router. :)
     
  9. renegade X

    renegade X Thread Starter

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    What I mean by bypassed the switch is; I hooked muy PC dirrectly to the cable modem. When I checked to see if any ports were available, there were none. I looked in the modems configuration, and there is no option for ports.

    I tried the telnet command from the DOS prompt, but it keeps returning "Could not open connection to the host, on port 23:", but I never typed in 23. How should I type the IP/port in the prompt?
     
  10. Monstrous Mi

    Monstrous Mi

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    I think I get what you are trying to do. However, you cannot simply manually open up a port on your PC. Some program has to be running which uses a certain port. Then that port will be listening.

    At a command prompt type in c:/netstat -a

    This will show you which ports are listening on your PC. If the port you want is listening it will show up. Then do the telnet command but add the port number. If you don't add a port number, it will default to 23. For example, on your PC, if you type in: c:/telnet localhost 2300 it will connect if 2300 is an open port.

    If you can do this on your PC and not from another PC on the Internet, then I believe your ISP is blocking it.
     
  11. angel

    angel

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    As Monstrous stated, some kind of server must be running on your machine and listening on a specific port(s). What server are you trying to connect to (vnc? ftp? telnet? something else?)? and what port did you configure it to listen on?
     
  12. renegade X

    renegade X Thread Starter

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    I am using VNC. With the tellnet command I typed the port that VNC is using (5900), and the prompt goes blank, verses givng that error. Does this mean that the port is waiting?
     
  13. Monstrous Mi

    Monstrous Mi

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    Yes, you are getting a connection. The port is open and listening.

    This is likely a firewall issue. Is there a firewall on the other computer you are using to try and connect? Do you have another computer on your home network that you can try to connect with?

    Also be aware that VNC requires a java-enabled browser, although your first step is the telnet command which will show at the most basic level that a connection can be opened.

    Finally, perhaps this will help: http://www.realvnc.com/documentation.html
     
  14. angel

    angel

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    On the PC with VNC server running, go to GoToMyVNC to verify port is open.
    Also, does your ISP give you a static IP or are you using something like DDNS?

    A note... even though I had my PC and router configured properly for VNC I was never able to connect to it from work due to restrictions on the work end. I found instructions somewhere about setting up an ssh tunnel or something but just figured it wasn't worth it. I ended up taking the easy route and now use LogMeIn (free version.
     
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