[Wylug-discuss] screen - cannot open ttys

[Paul Brook]

> I've a system running debian stable with 2.6.18.8-xen kernel and udev (its
> a xen domU so effectively its a regular linux system. Its headless & can
> only be accessed via ssh.
> 
> I can login fine & create subshells OK by running "bash" from within an
> active login, but if I run screen or try to create a subshell within
> screen
> 
> Cannot open /dev/ttyp3: Permission denied
> 
> ttyp3 exists & is unused.
> 
> any ideas? I do have root on this computer.
> 
> crw--w---- 1 aidan tty 3,  0 Nov 30 13:17 /dev/ttyp0
> crw--w---- 1 steve tty 3,  1 Nov 30 13:31 /dev/ttyp1
> crw------- 1 steve tty 3,  2 Nov 30 13:31 /dev/ttyp2
> crw--w---- 1 root  tty 3,  3 Nov 30 13:22 /dev/ttyp3
> crw--w---- 1 root  tty 3,  3 Nov 30 13:22 /dev/ttyp4

What do "who" and "tty" say?

I note that ttyp3 is owned by root. Are you also trying to switch users? i.e. 
did you login as root then su to a different user? If so that's your problem. 
ttys are deliberately only accessible by the user that created them. Giving 
other users access to your tty would effectively allow them to spy on you and 
run keyloggers.

Paul