Version:           KRDC: 4.2.00 (KDE 4.2.0) (using KDE 4.2.0)
OS:                Linux
Installed from:    Fedora RPMs

When you close a session in krdc the TCP/IP connection stays open. This is annoying when you're tunneling VNC connections through ssh, i.e. you are only able to exit ssh when you close krdc completely.

I have only tested VNC connections, so I don't know if this applies to RDP connections too. In my test I connected to a Xvnc running on the remote side.

Before starting krdc:

$ netstat -tnp | fgrep 5901
$

Starting krdc and setting up a connection to vnc://localhost:5901 which is tunneled through SSH to a remote host:

$ netstat -tnp | fgrep 5901
tcp        0      0 127.0.0.1:5901              127.0.0.1:50242             ESTABLISHED 3719/ssh
tcp        0      0 127.0.0.1:50242             127.0.0.1:5901              ESTABLISHED 3683/krdc

After closing the session, but krdc still running:

$ netstat -tnp | fgrep 5901
tcp        0      0 127.0.0.1:5901              127.0.0.1:50242             ESTABLISHED 3719/ssh
tcp     3470      0 127.0.0.1:50242             127.0.0.1:5901              ESTABLISHED 3683/krdc

After closing krdc:

$ netstat -tnp | fgrep 5901
$