Five Computers with DHCP behind Public IP on Cable Modem


I have cable modem service (Roadrunner in particular). On my network, I have five Macintosh computers running, each at a different 192.x.x.x local address. My public address is 74.x.x.x. Additionally, the cable people have ensured that each computer will always have the same local address, and that the public address will be static for us.

I’ve had the cable modem people forward ports 5900-5905 to each of the 5 computers (5901 to 192.x.x.1, 5902 to 192.x.x.2, etc)

Three of the computers are running OSX Leopard 10.5.6 (G5 Towers), one is running Tiger 10.4.11 or whatever the most recent 10.4 is (iMac Intel first issue) and one is running Panther OSX Server 10.3.9 (XServe G4).

All have the ARD option shut off, although all have been running it (we previously had static public IPs on every machine).

I have put Vine server on one of them (one of the Leopard machines) and can get it to work internally, setting it up as a desktop server. I can’t seem to find it on the public internet, though, using my public (74.x.x.x) address in the Vine viewer - nor does it come up in my shared list at Finder level, as it does when I am within the network).

Also, I’ve installed the Vine server on the other two Leopard machines, but when I go to START SERVER, nothing happens. They will not start. I’ve tried the Desktop and System servers. Each has been tried at AUTO for the Port, and I’ve tried the specific port that’s been forwarded to that internal IP address. But, the servers will not start.

I got the server to start on the first computer I tried. In order to try to get the other computer, I even tried quitting the Vine server on the first, but it did not help. The other computers do nothing when you hit START SERVER.

In Leopard, I’ve examined the Firewall under Security in the System Prefs, and it is set to ALLOW ALL INCOMING CONNECTIONS. Since I’ve only tried this on the Leopard machines, I’ve not looked at Firewalls on the other computers.

SOOOOO… my questions are:

  1. How do I configure a VNC setup that handles multiple computers behind a single public IP? Can Vine Server run on more than one machine and if so, why can I not START SERVER on more than one?

  2. How do I get to these machines behind the public IP address? There seems to be facility in Vine Viewer to add only that public IP address. So how do you find more than one computer behind it?

  3. Would I need desktop servers or system servers in this configuration? There is only one user per computer.

That’s it. I am newb to this, but thought I had a grasp of the basics. I hope I’ve stated the situation clearly. If not, please ask - I am desperate to make this work!

Please help!

Bob Martin

  1. There’s no problem running it on multiple machines. Check the console (/Applications/Utilities/ for messages concerning Vine (or OSXvnc), and let us know what you find.

  2. It sounds like you have things set up properly. You differentiate between the different computers by the port you have the VNC server running on.

  3. Either desktop or system servers will work. The system server will be available as soon as the machine boots up (before a user logs in) so you can access the machine without having a user auto logged in. The desktop server requires that a user be logged in and it launches under that user account. The main difference that you’ll see once they are running is that you can’t access the clipboard of the system server, while you can access the clipboard of a desktop server.

Thank you for the very quick reply.

I need to know, then, if there is only one public IP address, how are the various machines displayed? Will there be a selection box that comes up after the viewer makes contact that asks me to pick which I’d like to connect to?

Never having made it that far, I am not sure what to expect.



Actually you’ve done a very thorough job and are 95% of the way there. Let’s close the gap.

1- It sounds like you’ve done everything right with the router and the forwarding. You will definitely need to run each VNC server on the specific port forwarded to that machine (eg 5902 for 192.x.x.2, etc).

I don’t quite understand what is happening when you see the server will not start. You hit the start button and … it just never goes to “The server is running”? If that’s the failure then it almost sounds like the application got corrupted or something. Maybe you should try downloading it directly to that machine. You can also use the Server->View Log menu item to get more information.

2- You will access them from your external IP AND the particular port for that machine (that’s why having each port forwarded to a different machine (and VNC running on that port) is critical. Note – the Bonjour discovery ONLY works within your local subnet, so those machines will not appear via bonjour. If you use Vine Viewer it has an option to do an availability check. That check will work outside your network.

3- If your computers are set to auto-login then I would just run Vine Server as a Desktop server and set it to launch on Login. If you want to access the login panel you MUST run a system server.