Sharing abduco sessions

Some script to share abduco sessions with socat and SSH.

Client setup

Clone or download this repository.

Dependency	Viewing lectures	Giving lectures	Pair programming
SSH & shell	required	required	required
abduco		required	required
socat		required	required
dvtm		required	required on host
uuidgen			required on host
not Windows		required	required

Installation links (or use your package manager)

• socat
• abduco
• dvtm
• uuidgen: in your util-linux package, or something similar
• Not windows

Usage

Viewing a lecture

Before you start: press the space bar to leave. Run ./view <lecture>, replacing <lecture> with the lecture name your lecturer gave you. You should get a view of the terminal emulator of your lecturer in yours.

On windows? The script won't work for you, but if you have SSH on your computer (and you probably do), just running the command on the second line in the view script in a large command prompt window should work.

Pair programming

For one-on-one pair programming. The host should run the host script. The script will print out a session ID which should be shared with the guest. Then, it will open a new shell which is controlled by both the host and the guest. Yes, there may be remote code execution. Exit the shell to stop hosting.

$ ./host
Session ID: e989a26d-17dd-4d8e-bad3-43074f813148

The guest receives a session ID from the host and passes this to the guest script. Press Ctrl+\ to leave (or exit the shell, or shut down their computer).

$ ./guest e989a26d-17dd-4d8e-bad3-43074f813148

Giving a lecture

Run ./share <lecture>, replacing <lecture> with a nice name for your lecture (alphanumeric and - allowed).

Share the name of your lecture with your students so they can get a view of your terminal emulator. Exit the shell to stop sharing.

Server setup

Lecture viewing and pair programming require the same setup, with a different script. Do this twice (with a different user) if you want both.

Choose a username, e.g. pairing. Append to /etc/ssh/sshd_config the lines below:

PrintLastLog no
Match User pairing
	AllowTcpForwarding no
	X11Forwarding no
	PermitTunnel no
	GatewayPorts no
	AllowAgentForwarding no
	PasswordAuthentication yes
	PermitEmptyPasswords yes

Also comment the AcceptEnv line to avoid locale warnings and add pairing to the AllowUsers list.

If using pam, modify /etc/pam.d/common-auth to change nullok_secure to nullok to permit empty passwords with pam (as per https://superuser.com/questions/1152645/openssh-server-anonymous-account). Modify /etc/pam.d/sshd to comment out the two motd lines.

Create the user with the server/viewing (for lecture viewing) or server/pairing (for pair programming) script as shell and an empty password:

sudo useradd -m -s /home/pairing/shell pairing
sudo su -s /bin/sh pairing
cp <the script> shell
chmod 500 shell
exit
sudo passwd -d pairing

Fork this repository and change the SERVER constant in the scripts (or instruct your student to change it).