Server refused to allocate pty

[JessieG]

Can anyone help? I'm trying to login using "putty" though ssh but I got the above error?

[Joseph Loo]

hi jessie,

wat is the max. no. of pts devices:

# kmtune -q nstrpty

also the number of pts devices available:
# ls /dev/pts | egrep -i '^[0-9]' | wc -w


regards.

[Sameer_Nirmal]

Hi,

Check the kernel parameter "npty" using
# kmtune -q npty

Check the current useage of the ptys being used
# ps -ef | grep pty | wc -l

If the usuage is less than "npty" kernel value , then creat ptys using
# insf -d pty -n
This will creat devices files( ptys ).

If the useage is more that "npty" , the you need to increase the kernel parameter. It will require kernel rebuild and reboot.

[JessieG]

Please see the output below. I still have enough no. of pts devices available. Any ideas?

#kmtune -q npty
npty 60 - 60

#ps -ef | grep pty | wc -l
2

#ls /dev/pts | egrep -i '^[0-9]' | wc -w
60

[Sameer_Nirmal]

Hi again,

I over-looked the subject error message, Sorry....

SSH uses stream based pseudo terminal named as "pts" and not "pty". Hence the number of "pts" device files in "/dev" and "nstrpty" kernel parameter are relevant for SSH.
Since you see the "pts" device files are 60, maybe "nstrpty" would be same number. Better check it using kmtune.
Check of "pts" in used using "ps -ef".
If less create the device files using
# insf -d pts -n

Which version of SSH installed on the server?
Where do you see this message?
Any error in syslog,demsg?
Check if "sshd" daemon is running
Is the system is Trusted system?

[JessieG]

Hi please see answers below. Current nstrpty value is also 60

Which version of SSH installed on the server?
A.03.10.002 HP-UX Secure Shell

Where do you see this message? During login, after entering the username and password, I got the following display plus garbage characters.

Server refused to allocate pty
ttytype: couldn't open /dev/tty for reading

Any error in syslog,demsg? I got lots of error like :

error: /dev/ptmx: Device busy
error: session_pty_req: session 0 alloc failed

Check if "sshd" daemon is running
Yup, it is running

Is the system is Trusted system? No

Here's the output of :

#ps -ef | grep pts | wc -l
125

[Joseph Loo]

hi jessie,

after looking at your latest reply, it seems a restart of ssh is required.

most importantly, use the latest version of secure shell:

http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=T1471AA

v3.10 is really old.

regards.
(p.s. please assign points.)

[Arunvijai_4]

Hello Jessie,

Secure shell version A.03.10.002 is very old and the latest is A.04.20.004. You can download it from, http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=T1471AA

-Arun

[Sameer_Nirmal]

Hi,

"error: /dev/ptmx: Device busy" is a real problem. The error you are getting makes a sense for this problem.

The "/dev/ptmx" is a Master pty driver . This device driver should get accessed so that alongwith slave device driver "/dev/pts/" , it will allow the terminal connection.
Check who is using the "/dev/ptmx" device using
# fuser -u /dev/ptmx
You need to kill those processes using
# fsusr -ku /dev/ptmx

Then you should able to log-in.

As mentioned by others, it is always better to have latest version as it contains many fixes for issues encountered in the old versions and new features as well.