> [...] They all three have static IP addresses. [...]
LAN IP addresses? Do you mean actual static addresses (configured on
the computers themselves), or reserved dynamic addresses (configured on
(the DHCP server on) the C3000 router section)?
> [...] I can forward Port 3389 to one of them [...]
True, but you can forward other ports to the other two systems (or,
as I'd advise, to all three).
> [...] I use Remote Desktop App [...]
On what, another Windows system, or a Mac, or some other?
> [...] and apparently are restritcted to that particular port.
Not so. You can specify a different port number in the "PC name"
field where your connection is defined.
You might, for example, specify port-forwarding rules like the
following (all TCP):
Ports
External Internal Server Address
14389 3389 PC1_LAN_addr
14390 3389 PC2_LAN_addr
14391 3389 PC3_LAN_addr
On the client side, you'd specify a "PC name" like:
<your_public_IP_address>:14389
<your_public_IP_address>:14390
<your_public_IP_address>:14391
When exposing a well-known service like Remote Desktop to the outside
world, I would not use the default port (externally). Why make it
easier for a lazy attacker to guess the right port?
I believe that it's also possible to configure the Remote Desktop
server on each system to use a non-default port, but I'd prefer to keep
things simple for intra-LAN communication, and let the router translate
the odd-ball external port numbers for external traffic.
