Share screen session with users in the same group (Linux)

Question

I can create a detached screen session using the following command:

[user1@host-pc ~]$ screen -d -m -S sname program

...and resume to it using this command:

[user1@host-pc ~]$ screen -r sname

Is there a way to let users that are in the same group as user1 access the session?

Edit: I've read the man page, and I know about the multiuser mode. I'm asking specifically about allowing to share screen sessions by user groups (/etc/group).

i.e. all users in group users are allowed to share session sname. Without manually acladd'ing each user to screen.

Answer 1

You can enable multiuser mode either via .screenrc, or within the session by using Ctrl+a : with multiuser on. Access can then be controlled by adding individual users with acladd user2, or by re-creating group lists within screen acls (aclgrp).

I do not believe there is a way to directly use unix groups for screen multiuser ACLs.

See man screen or http://aperiodic.net/screen/multiuser

Answer 2

Yes, it is possible, but your screen should have suid bit on and this has some security implications. Basically you should do the following in order to be able to share a screen session:

chmod u+s /usr/bin/screen

Then as a user (let's suppose that its username is user1), you should run screen and run the following two commands in it:

<ctrl+a>:multiuser on
<ctrl+a>:acladd user2

Finally, user2 should be able to connect to the session with the following command:

screen -x user1/

You can find more information here.