/dev/tty keeps changing permissions..?

Thomas Park tpark at drivespeed.com
Mon Jun 9 09:44:19 PDT 2003

> -----Original Message-----
> From: Matthew D. Fuller [mailto:fullermd at over-yonder.net] 
> On Sat, Jun 07, 2003 at 10:21:17PM -0700 I heard the voice of
> Thomas Park, and lo! it spake thus:
> > I've been having an interesting problem with my FreeBSD 5.0 
> install -
> > for whatever reason, the permissions and ownership on 
> /dev/tty keep on
> > being automatically changed in such a way that it becomes 
> impossible for
> > most users of the system to initiate outbound SSH sessions.
> If you're having a problem with ssh, /dev/tty permissions 
> have nothing to
> do with it.  It's something of a phantom device which always refers to
> YOUR tty.  YOUR tty will naturally be owned by you, and 
> either 620 or 600
> (depending on mesg(1)).  Vis:

Interesting.  I have access to several FreeBSD 4.6 STABLE boxes, and
/dev/tty on each of them looks thusly:

crw-rw-rw-  1 root  wheel    1,   0 Jun  8 15:26 /dev/tty
crw-rw-rw-  1 root  wheel    1,   0 May 31 23:06 /dev/tty

etc. - all owned by root:wheel and all mode 0666.

The only system that has user level ownership / permissions is the BSD
5.0 box.

> So, something else would be causing your ssh permissions.  
> We'd need more
> details to try and track that down.

I'm pretty sure the ssh problem is with /dev/tty - I've scoured quite a
few message boards and newsgroups looking for a solution to the SSH
problem.  The symptom:a user who doesn't currently own /dev/tty attempts
to open an outbound SSH session and gets a permission denied error with
an error message along the lines of "Host key verification failed."  SCP
likewise doesn't work.

The fix suggested on the various newsgroups was to chmod 666 /dev/tty -
pretty much in line with the permissions that I have on the 4.6 boxen.

If you could suggest other culprit locations to try looking in, I would
very much appreciate it.


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