I finally figured out why I was getting this message:
geoff at newzippy:~$ ssh dammit
You have no controlling tty. Cannot read passphrase.
As root I wouldn't get this, so I figured it to be some permission
problem.
Using strace I see:
open("/dev/tty", O_RDWR) = -1 EACCES (Permission
denied)
write(2, "You have no controlling tty. Ca"..., 54) = 54
then comparing the permissions on /dev/tty between the this system, and
another where I am not having the problem I see that /dev/tty wants to be
world writeable.
I don't know if this is the best case, but it seems most my boxes have
this. The system I got that didn't have this set was Essential Debian
from CheapBytes, which had similar odd settings like read-only /dev/null
and /tmp
I hope this helps.
Geoff Cummins