Vncsend

vncsend (note lower case) is one half of the vncsend/vncrecv pair of programs which allow a current VLAB or lab computer session screen to be shared with another user.

Intended uses:

1. A tutor in a class who, while helping a student at the student's computer, decides that it might be useful for the rest of the class to be able to see what the tutor is doing. vncsend can be run on the student's computer to "project" the student's screen to the large monitors connected to the tutor's machine (which would already be running vncrecv).
2. Two students working in a pair, can share either of their lab computer or VLAB screens with any other lab computer or VLAB screen they're using, locally or remotely.

vncsend and vncrecv are both command-line programs.

vncrecv is run first. It takes an optional TCP port number on which it listens for incoming connections from vncsend. If this port is not specified it defaults to 65509.

vncsend is then run inside the session that you want to share. It takes one or two arguments:

1. The first is the name or IP address of the host running vncrecv, and
2. An optional second argument is the TCP port to share to. This would be useful when multiple users on, say, a VLAB host, are using vncrecv at the same time.

Notes

• vncsend and vncrecv use a VNC server (vncsend) and a VNC viewer (vncrecv) to do most of the magic. Because using VLAB also uses a VNC viewer, the default VNC viewer menu key of F8 is changed in vncrecv to F7 so exiting a shared session in VLAB via the viewer menu doesn't accidentally actually exit your VLAB session.
• For security, the VNC sessions don't use TCP connections and instead use UNIX sockets (which can be owned by the user and have appropriate permissions to limit access) to avoid snooping.
• Once started, the mouse and keyboard on BOTH screens are active.
• vncrecv will only accept connections originating from CSE lab or VLAB subnetworks.