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Accepted
florianbaethge
Asked: 2011-02-11 09:13:40 +0800 CST

Failing to connect to server via SSH - "Server refused to allocate pty"

  • 772

I have a STRATO V-PowerServer running with Ubuntu 10.10 for my stuff but lately have problems connection to the server via ssh.

Basically all I have is ssh-access to the server and if necessary I can boot into a recovery-mode where all my stuff is in /repair so that I can do any fixes on the system.

The problem is, that when I try to connect to the server via ssh I get this error:

Using username "florian".
[email protected]'s password:
Server refused to allocate pty
Linux hwn36335 2.6.18-028stab070.5 #1 SMP Fri Sep 17 15:37:23 MSD 2010 i686 GNU/Linux
     Ubuntu 10.10

                 Welcome to Ubuntu!
                                    * Documentation:  https://help.ubuntu.com/
                                                                              /home/florian/.zlogin:1: command not found: display_info

So the shell doesn't open and I can't enter any commands. I've already tried to google for "Server refused to allocate pty" but couldn't find anything that helped, though the problem has happened to other people before. Additionally, I sometimes even get a different error: "pty allocation request failed on channel 0" instead of the other error. For this problem all I could find was this:

http://blog.dinotools.de/2010/10/03/fehler-pty-allocation-request-failed-on-channel-0

But unfortunately it didn't help...

Does anybody have an idea why this error is caused and what I could try to fix it?

Would be great if you could give me tips. I know some basic things and know how to work with my server but if it goes this deep into problem-solving I am at my limits... ;-) Thanks!

Addition 1:

/var/log/auth.log

Jan 24 16:20:01 h1696522 CRON[3417]: PAM unable to dlopen(/lib/security/pam_smbpass.so): /lib/security/pam_smbpass.so: cannot open shared object file: No such file or directory
Jan 24 16:20:01 h1696522 CRON[3417]: PAM adding faulty module: /lib/security/pam_smbpass.so
Jan 24 16:20:01 h1696522 CRON[3417]: pam_unix(cron:session): session opened for user www-data by (uid=0)
Jan 24 16:20:03 h1696522 CRON[3417]: pam_unix(cron:session): session closed for user www-data

/var/log/daemon.log

Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50003.vdb - dwr50003.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50004.vdb - dwr50004.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50005.vdb - dwr50005.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50006.vdb - dwr50006.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50007.vdb - dwr50007.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50008.vdb - dwr50008.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwr50009.vdb - dwr50009.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/dwrtoday.vdb - dwrtoday.vdb with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/updates/timestamp -    timestamp with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: /var/drweb/bases/update.drl -   update.drl with such CRC32 already exists, downloading has been skipped
Jan 24 16:00:02 h1696522 update.pl[14292]: deleting old files ...
Jan 24 16:00:02 h1696522 update.pl[14292]: moving downloaded files from temporary to working directory ...
Jan 24 16:00:02 h1696522 update.pl[14292]: sending notifications ...
Jan 24 16:00:02 h1696522 update.pl[14292]: summary => updated: 0, removed: 0 files and 0 messages
Jan 24 16:00:02 h1696522 update.pl[14292]: Finish Success:   2011-01-24 16:00:02
Jan 24 16:00:02 h1696522 update.pl[14292]: Socket path is /var/drweb/run/updateSock
ubuntu login ssh ubuntu-10.10

5 Answers

  1. If you have console access

    mount devpts /dev/pts -t devpts
    • 7
  2. Best Answer

    Did you tried to re-create pty and tty devices ? 

    [email protected]:~# /sbin/MAKEDEV tty
[email protected]:~# /sbin/MAKEDEV pty

    It seems to be a known issue on virtual servers...

    If you don't have access to any shell, you could try sending the command via ssh : 

    florian@localmachine:~$ ssh [email protected] "/sbin/MAKEDEV tty"
florian@localmachine:~$ ssh [email protected] "/sbin/MAKEDEV pty"

    Edited to reflect your comment :

    If you use a chroot, you also have to mount /proc, /dev and /sys : 

    root@h1696522:/# mount -o bind /proc /repair/proc
root@h1696522:/# mount -o bind /dev /repair/dev
root@h1696522:/# mount -o bind /sys /repair/sys

    It should work now.

    • 3

  3. The times I have encoutered this error I fixed it certifying that the udev package was installed and running. Udev takes care of creating device nodes when they are needed, like the PTS/x that are needed by ssh. Give it a try.

    • 3

  4. Try this:

    ssh root@host "mount -o remount /dev/pts"
    • 1

  5. I had to do a combination of what is posted here. My permissions were wrong and /dev/pts was already mounted. 

    mount -t devpts -o remount,seclabel,nosuid,noexec,uid=0,gid=5,mode=620 devpts /dev/pts

    Use this to verify that your permissions are correct. 

    grep devpts /proc/mounts

    Also check /dev/pts. It should be 755 and owned by root.

    ls -dl /dev/pts
chmod 755 /dev/pts
chown root:root /dev/pts

    Check sshd_config file. PermitTTY should not be set to no. If it is either comment it out or set it to yes. Then restart sshd. 

    vi /etc/ssh/sshd_config
service sshd restart
systemctl restart sshd
    • 0