[lug] ssh login error

Steve Webb steve at badcheese.com
Wed Jan 10 10:33:59 MST 2007

I don't have much experience with the devpts file system mounted at 
/dev/pts, but I see that more devices are made when I open more terminals 
or screen sessions on my machines.

In my /etc/fstab file, I have the mount params as:

devpts       /dev/pts        devpts  gid=5,mode=620  0 0
(yours said "none" as the first option in your first email)

Also, check to see that your kernel supports the devpts stuff:
"grep pts /proc/filesystems"

Also, make sure that sshd (if you built it yourself) also supports the 
devpts stuff.

On my FC6 machine, there's an /etc/sysconfig/console dir, but it's empty 
on my machine.  Perhaps you can set some startup or config parameters in 

That's about all that I can come up with.  Hope it helps.

- Steve

On Wed, 10 Jan 2007, D. Stimits wrote:

> Date: Wed, 10 Jan 2007 03:25:08 +0000
> From: D. Stimits <stimits at comcast.net>
> Reply-To: "Boulder (Colorado) Linux Users Group -- General Mailing List"
>     <lug at lug.boulder.co.us>
> To: "Boulder (Colorado) Linux Users Group -- General Mailing List"
>     <lug at lug.boulder.co.us>
> Subject: Re: [lug] ssh login error
> Lee Woodworth wrote:
>> D. Stimits wrote:
>>> Steve Webb wrote:
>>>> I had a similar experience on a hosted server (vmware-type situation) 
>>>> where they limited the number of PTYs that I had (I was running GNU 
>>>> 'screen' and ran out of PTYs pretty quickly).  I asked the hosting 
>>>> company to adjust the number of PTYs so I could spawn more 'screen' 
>>>> sessions and it kind of went away.
>>> Everything seems to center on this, but I know the CentOS kernel is not a 
>>> dumbed-down kernel, so I can't imagine I have to recompile for pty's. 
>> The kernel has an option for legacy unix ptys (probably not the exact 
>> name).
>> This enables /dev/ptys. It doesn't have to be enabled. I don't have any
>> /dev/ptys on my systems, they use the newer device names and the devpts 
>> file
>> system.
>> Check for the character device /dev/ptmx (c 5 2) root, root 0666
>> and the /dev/pts dir. These are signs you have the newer pseudo
>> terminal setup. Also a plain mount command would show this line:
>>    devpts on /dev/pts type devpts (rw)
>> The newer setup creates the /dev/pts/<n> dir entries as needed.
>> They will have the ownership of the login using the pty.
> This indicates the system is entirely non-legacy via the ptmx and 
> /dev/pts/<number>. Why it would fail to be able to get a pty is a mystery, 
> the /dev/pts/ only has a couple of entries when it fails...and of course 
> sometimes it works and has a couple dozen entries.
>> Don't know why you are having issues. There are consoles, virtual 
>> terminals, and
>> pseudo terminals that one can use for login. I think gettys manage the
>> console and the virtual terminals ctl-alt-fn<1....7>. Net daemons like
>> ssh use pseudo terminals for the I/O.
> Is there some sort of adjustable limit like accounting that would cause it to 
> not produce more pty's in /dev/pts/ when there are only 2 or 3 there?
> D. Stimits, stimits AT comcast DOT net
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EMAIL: (h) steve at badcheese.com  WEB: http://badcheese.com/~steve

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