Ok, I may have the unsolvable problem here worth looking into. To generalize, we cannot connect to a specific win2000 server WHEN it is on a specific IP, from a specific geographic location, only from windows clients (desktop or VM), BUT NOT from an Ubuntu RDP client. Did you get all that? We think it has to be from our ISP, but we not sure how. As a matter of fact, nothing about our solution makes any iota of sense.
If you are still curious, or curiously confused, please read on. I'd like to know how and why this is fixed (although not really), because none of us here can wrap our head around this.
REMEBER: Our solution was to change the (actually add a second) outside IP address for our win2000 Server. This fixed it.
Yesterday, we had problems RDPing into one of our many Win2000 servers we use. At first we thought it was licensing, and maybe it still is, but set that aside for a moment. We have two locations with two ISPs. Location A is where our staff is. We have a business account with mid continent, a couple static IPs. Location B is in another geographic location with a different ISP on a dedicated T1 connection. Loc B is where all our client hosting servers are located. All of their servers I mentioned are on a KVM-VM environment. One of the Win2000 servers I'll say is on public IP x.x.x.09. We have a clone of this same VM that does other functions, and it is on IP x.x.x.03.
At some point yesterday, we could no longer RDP into x.x.x.09 using any windows type client. XP, 2000, win7, vista, etc (either desktop or VM). We could log into x.x.x.09 using Ubuntu's RDP client. So we assumed it must be a licensing problem. But, we could still log into x.x.x.03. These machines are identical as far as licensing goes.
Anyway, we did not know until today, that all of our other clients nation/world wide could still get in using IP x.x.x.09. So everyone could get into location B, unless you were at location A … AND using windows not ubuntu.
So, one of our IT guys got a crazy idea, add a second IP to the machine. So you can now get to the non-working server machine using either of the two outside IPs x.x.x.09 or x.x.x.05. Well, wouldn't you know. Everyone at Loc A, using a windows RDP client can now log in with no problems using x.x.x.05. We still have problems with IP x.x.x.09, but only if you are in Loc A, and using a windows RDP client. Ubuntu RDP client can connect to either x.x.x.09 or x.x.x.05 from Loc A. And, if you are anywhere else in the world, x.x.x.09 is just fine.
If a block or a DOS was on the firewall, then it didn't matter if I was using a Windows RDP or Ubuntu, no one would get in, but Ubuntu does. ====> this points to No Firewall blocking, not a DOS attack
If there was a real problem with the win2000 server, then adding another outside IP would NOT have fixed this problem ===> this points to a network problem, not a server problem.
If other people around the world can get in, but Loc A cannot ==> points to a problem with our network, or mid continent.
My assumption is that mid continent is throttling our RDP traffic on this specific address and port. But why then does ubuntu RDP client work? ===> Point to Ubuntu RDP client is somehow better than Windows RDP client, and indeed mid continent is throttling our traffic.
I hope someone else can shed some light on this issue.