VNC viewer connects on iPhone but not work PC

By Animalhungry ยท 6 replies
Oct 10, 2008
  1. Hi - I've been trying to get remote access up and running so I can control my home PC from my work office. I've installed TightVNC Server on the home XP SP2 PC, setup a static IP address and DNYDNS and then forwarded the VNC server ports on my home router.

    Using the TightVNC Viewer I can remote in from another PC (running Vista Home Premium) on the same network and using Mocha VNC via wi-fi I can remote in on my iPhone on the same network i.e. connecting to my home wi-fi that both PC's also connect to. I can also connect using Mocha VNC on my iPhone using the Edge connection i.e. not on the same network as the VNC Server machine.

    However, I cannot connect using TightVNC viewer from my office XP SP2 PC. I can't even ping the VNC server machine (using the dnydns domain name) from my office machine. When I went on to I also couldn't ping my dyndns domain name.

    What I don't understand is how the crappy iPhone can connect (albeit at an almost unusable refresh rate) but my PC in my office can't connect. Also I don't know how my iPhone can connect over Edge but I can't ping the dnydns address even using a web-based ping test.

    If anyone has any ideas where I might start troubleshooting this, they would be much appreciated.

  2. tuant

    tuant TS Booster Posts: 202

    firewall is off?
  3. Animalhungry

    Animalhungry TS Rookie Topic Starter

    Sorry, which firewall? I have a firewall (at least one - we're a big company) at work which my employer's IT team controls, and then I have a software firewall on the VNC server machine and the router's hardware firewall at home.

    My home firewall (Zonealarm) is always on and I have used VNC with it before and given it full rights to act as a server and access the net etc. In any event, my iPhone can get through to it via Mocha VNC so I didn't think that would be the problem. What should I check?

    Could it be something on my work PC or on the work network preventing me from accessing the net? Do certain ports need to be open on the VNC viewer PC at work for it to work? I could run a netstat -a from the command prompt to find open ports I guess, but I thought VNC Viewer just needed a regular net connection like an internet browser?

  4. Animalhungry

    Animalhungry TS Rookie Topic Starter

    So here's more info. I just went to shieldsup and probed port 5900 and it says:

    Port 5900

    vnc access

    Virtual Network Computing

    This port (and port 5800) are opened by the VNC system allowing remote multi-platform console access.

    Related Ports:

    Then at it says:

    Checking you out at IP address "**.**.13.36"...

    **.**.13.36 is accepting connections on Display 0 (TCP port 5900).

    **.**.13.36 is not responding on Display 1.

    **.**.13.36 is not responding on Display 2.

    **.**.13.36 is not responding on Display 3.

    **.**.13.36 is not responding on Display 4.

    **.**.13.36 is not responding on Display 5.

    **.**.13.36 is not responding on Display 6.

    **.**.13.36 is not responding on Display 7.

    **.**.13.36 is not responding on Display 8.

    **.**.13.36 is not responding on Display 9.

    Scan of "**.**.13.36" is complete.

    Hit 'reload' or 'refresh' in your browser to scan again.

    Also, I can connect between computers behind the same firewall, and the iPhone connects over its Edge network.

    So, it looks like my VNC server PC is accepting VNC traffic and should work so the problem must be my work PC running the VNC client? What can I do to test my work PC?

  5. jobeard

    jobeard TS Ambassador Posts: 11,177   +990

    Likely the firewall at work disables outbound 5900; typical of the I.T. department.

    Get permission and they will assist you in the setup.
  6. Animalhungry

    Animalhungry TS Rookie Topic Starter

    Thanks, I'll speak to the IT dept. If they are not willing to help me is there any way I can identify open outbound ports on my work PC and then tell the VNC server (and client?) to use that open outbound port? Would I just have to change the port the server uses from the default 5900 to the same number port as the open outbound port on my work PC (and forward it on my home router, of course)?

  7. wilcan888

    wilcan888 TS Rookie

    Hi, there

    Have you try using a different remote admin software, like teamviewer, or radmin, try it, it may work, but you must install and configure your office PC and your home, and by the way, have you try to configure your pc firewall? try unblocking it, or configure your routers firewall and port settings.


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