UltraVNC

I'll double check with the person holding the viewer that he is using version 1.0.1. He only downloaded and installed it today, he may of clicked the wrong link somehow.

Well, the machines that are having the problems are the ones running the SC software. They are initiating an outgoing connection to a waiting vncviewer. I dont think having that viewer run on a different port is going to make any difference.

The machine that is awaiting a connection from one of my ...

No.

Network topology is:

ADSL, 8 IP Block
Zoom x3 ADSL Router, NAT disabled.
Debian Box running iptables with source natting. Amongst other things.
-- 2 network cards, 1 going to router, 1 to a 5-port switch with internal LAN
2 PCs on LAN, the OP issue happens with both.

When the connection is ...

I'm having a problem on 2 machines, both fresh installs a week ago, although they both have a similar software setup, hardware wise they are miles apart.

We have Computer A being either of the above mentioned PC's, and Computer B is the one with UltraVNC Viewer in Listen Mode.

A dbl clicks the SC ...

heh

Another way, to make things slightly easier, is to make a shortcut on the desktop, or quick launch, or a batch file, with this command.

rundll32.exe user32.dll, LockWorkStation

Good luck.

You could pass ctrl-alt-del and choose lock computer from the corresponding option window.

hm, yeah, I guess that is theoretically possible. As the NAT router will know within its own database which ports on the internal PC to actually send the packets.

Now thats interesting. The original RFC 2663 for NAT states each connection should be uniquely identified by Source IP/Port and Target IP/Port. Some companies must of decided to change this implementation specifically for peer-to-peer when both are behind NAT. Perhaps UPnP is what is being exploited ...

Which weekend would this be?

What you are working on isnt possible with NAT. It isnt possible for you to simply pass on a connection.

The way NAT works is an outgoing connection from internal IP to outside internet is tracked, so the rebound packets, coming from the original destination back to the original sender are ...