[lug] ssh login error

[Steve Webb]

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.

I think that you can adjust the number of PTYs in the kernel config 
somewhere, so if you can recompile the kernel, might want to poke around 
in there a little (device drivers -> character devices -> number of legacy 
PTY in use (mine's set to 256)) and I have tons of /dev/pty* and /dev/tty* 
entries in my /dev dir.

- Steve

On Mon, 8 Jan 2007, D. Stimits wrote:

> Date: Mon, 08 Jan 2007 01:49:05 +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: BLUG <lug at lists.lug.boulder.co.us>
> Subject: [lug] ssh login error
> 
> There is an sshd error sometimes occuring on logins to a centos 4.4 server. 
> The error shows up in several google searches, but I'm at a loss figuring out 
> why it is happening. The error showing up in /var/log/secure:
> error: openpty: No such file or directory
> error: session_pty_req: session 0 alloc failed
>
> It does not always occur. For a long time I had it stopped by using bash 
> login, whereas it had failed more often under tcsh before. I can remove the 
> init files of the shell, and it still happens, though less often. I can 
> create pty's via MAKEDEV, it still happens. There was one hint that if I add 
> to the kernel boot line:
> devfs=mount
> ...that it would fix it, but I have the fstab entry:
> none     /dev/pts    devpts  gid=5,mode=620  0 0
>
> So this should not matter, and if it did, it should always be a problem, not 
> mysteriously showing up some days but not others. I have all of the ptys, and 
> I have the devpts mount line. sshd is kept up to date. The kernel is the 
> stock centos 4.4 kernel with yum update. Can anyone suggest what the source 
> of this problem is? I know it can't make a pty, I guess I'm wondering how 
> that could even happen. I'm a bit frustrated by it, and despite how painful 
> it would be, I'm tempted to just reinstall using fedora instead (the server 
> has been up for a month, and I had thought it was about ready).
>
> D. Stimits, stimits AT comcast DOT net
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-- 
EMAIL: (h) steve at badcheese.com  WEB: http://badcheese.com/~steve