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[Solved] LISH/SSH Access Denied
https://forum.linode.com/viewtopic.php?f=19&t=7481		 Page 1 of 1
Author:  bltc [ Thu Jul 28, 2011 5:18 am ]
Post subject:  [Solved] LISH/SSH Access Denied
Running ubuntu 9.10

Presenting two symptoms which may or may not be related

1> SSH returns connection refused on all ports/accounts.
2> No login prompt appears in LISH/AJAX after bootup messages. The LISH console is available(CTL-CAD), but the login prompt refuses to appear.

I've logged in to recovery profile and disabled firewalls, checked and changed ports, the SSH server appears in the console logon messages.

I am able to use SSH/LISH when started in the recovery profile.

I havent noticed anything apparent in the logs, although a brighter mind may be able to point me to an issue.

I have used pub key SSH without a hitch until this occurred. As I haven't made any major changes, except rebooting. I am assuming that an update or other change borked it but did not take effect until reboot.

All other services appear to be running as normal.

Any advice, pointers, solutions or workarounds would be greatly appreciated.
Author:  obs [ Thu Jul 28, 2011 6:30 am ]
Post subject: 
If this happened after a reboot I'd say the ssh server isn't starting for some reason.

The lish part will be you're linode is using the wrong console, for linode it's hvc0

Are you using a custom kernel?

On another note, support for ubuntu 9.10 ended in april, once this is fixed you should upgrade to 10.04.
Author:  bltc [ Thu Jul 28, 2011 7:17 am ]
Post subject: 
Thanks for they reply.

Latest 2.6 Paravirt kernel, nothing special should be compiled.

I will indeed be upgrading after I can access the machine again.

Assuming I can likely fix the SSh issue, how do I go about the hvc0?
i've had a brief look round.

Most of the "guides" related to this are for other distros and have inittab or event.d alterations?

there is indeed a /dev/hvc0, and it looks like the correct settings in /etc/init.

I must admit zip experience in this area, so any pointers, or links to send me in the right direction?
Author:  obs [ Thu Jul 28, 2011 7:46 am ]
Post subject: 
Check that hvc0 is in your /etc/securetty file on your server, boot into rescue mode to verify this. (remember to mount your distros drive and check that securetty file not the finnix securetty)
Author:  bltc [ Thu Jul 28, 2011 7:56 am ]
Post subject: 
Present and accounted for.

# This file defines which devices root can log in on.

# These are the ttys on the physical console:
console
tty0
tty1
hvc0
xvd0
Author:  obs [ Thu Jul 28, 2011 8:18 am ]
Post subject: 
Check that you have an /etc/init/hvc0.conf file and it contains

Code:
# hvc0 - getty
#
# This service maintains a getty on hvc0 from the point the system is
# started until it is shut down again.

start on stopped rc RUNLEVEL=[2345]
stop on runlevel [!2345]

respawn
exec /sbin/getty -8 38400 hvc0



If that's there and looks right then poke linode support since they can see your server they'll be able to look at it closer.
Author:  bltc [ Thu Jul 28, 2011 9:37 am ]
Post subject: 
looked at that too, thanks for the help!
Author:  bltc [ Fri Jul 29, 2011 5:13 am ]
Post subject: 
Just to update in case others have similar problems.

I changed to an older kernel allowing access with root password in maintenance mode. Fixed the SSH problem which was caused by a corruption in sshd_config.

The Lish problem was caused by getty not loading on boot. Manual starting of the process by upstart or directly through /sbin/getty worked.

To make it persistent, I updated the /etc/init/hvc0.conf file as follows:
Code:
          start on (virtual-filesystems
          or starting rcS
          or starting mountall-shell)

stop on runlevel 0
stop on runlevel 1
stop on runlevel 6

respawn
exec /sbin/getty 38400 hvc0


Returned to Latest 2.6 Paravirt kernel in profile.
Rebooted.
Solved.
Author:  Guspaz [ Fri Jul 29, 2011 11:42 am ]
Post subject: 
As a warning, Ubuntu 9.10 is EOL and is not receiving any updates of any kind. You very much need to upgrade or downgrade to a supported version. Here are the EOL dates for the server versions of Ubuntu releases that are still supported:

8.04 LTS: April 2013
10.04 LTS: April 2015
10.10: April 2012
11.04: October 2012

Generally, people running production servers at Linode should stick to the LTS releases. They come out every two years, are supported for five years, and you can upgrade directly between them without going through the intermediate releases (although you can do that too if you want).

There's no real reason not to run a non-LTS version on a server, except for the fact that they're typically only supported for 18 months, requiring frequent updates to stay on a supported version. With an LTS release, you can afford to stay on the same release for up to five years, which really gives you the flexibility to upgrade on your own schedule.

One thing some people like to do for maturity, for example, taking advantage of that flexibility, is upgrade every 2 years to the *previous* LTS release; by the time they upgrade to a newer release, it's already had two years to mature.

Personally, I stick to the LTS releases on my production boxes, and typically upgrade to it after the subsequent release comes out the following October (6 months later). It's my compromise between not wanting to have a brand new release on my box, but also not wanting to fall too far behind. My non-production box (the one I use for personal use, development, messing around) I just keep on the latest-and-greatest release, since stability isn't as important.
Author:  db3l [ Fri Jul 29, 2011 3:16 pm ]
Post subject: 
bltc wrote:
I changed to an older kernel allowing access with root password in maintenance mode. Fixed the SSH problem which was caused by a corruption in sshd_config.

For future reference, it's also possible to fix items such as this without switching kernels by booting into a recovery (Finnix) configuration, mounting your disk volume and then making the change. That will work even in cases where changing kernels isn't an option or won't affect the behavior.

-- David
Author:  bltc [ Sat Jul 30, 2011 11:57 am ]
Post subject: 
I did have access to the file system through a recovery profile. The kernel switched allowed me access to a version of my VPS that was actually running however letting me see what was going on when actually booted.

As far as the upgrade goes, that certainly was a most detailed post. I have completed upgrading and should be good for a few more years. Except for a sticky SQL problem all went well But then I supposed thats why I have backups and DB dumps.

-bltc
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