broken ssh

Karl Auer kauer at
Sun Jun 13 12:10:38 UTC 2010

On Sun, 2010-06-13 at 07:44 -0400, Mark C. Miller wrote:
> During my school year, I was able to ssh into my box which, has a domain 
> name assigned by DYNDNS. I used "Places >>Connect to server" to do this. 
> Connectivity ceased the last week of May while running 9.10. Now, when I 
> try that, it connects (accepts my login ID), but stops at the password.

Does this mean that after entering the password, it "hangs" (no further
output) or that it does not accept the password, saying "try again", or
that it never issues a password prompt at all?

>   I use the same password that I use to login under that system ID on 
> the box itself.  The password works to login to the system directly. 
> I've tried loogging in from the command line:  "ssh 
> eyore15 at" works.  It then asks for my password and 
> then will not accept the assigned password for the system. I also:

So does it work or not? You say it works, but in the same sentence that
it will not accept your password. Which is true?

Here is what needs to be in place on the target machine:

1. Make sure the package openssh-server is installed.

2. Make sure the sshd daemon is running (ps ax | grep sshd)

3. Make sure sshd is on port 22 (netstat -an | grep 22 | grep "^tcp")

4. Make sure that your home router port forwards port 22
   (or whatever port you like) to port 22 on the target computer.

Now try to ssh to the target computer locally (i.e., from itself, while
logged in on a console or X terminal). Wait AT LEAST two minutes before
giving up - the server could be doing an ident check or reverse DNS

If the local login works (eventually) everything is OK. If there was a
big delay, check the sshd-config settings to make sure it doesn't do
ident and DNS checks, which are pointless anyway.

Then try a remote login (i.e., from a  different computer).

If you never get a prompt, suspect a firewall.

If your password is rejected, check the sshd-config settings, make sure
connections are permitted from your IP address etc.

Make sure, when you attempt a remote ssh login, that you are logging in
from an account with the same name as on the target computer, OR specify
the target account name explicitly (i.e.m ssh myname at target...) You'd me
amazed how often people forget they are logged in as arthur when they
try to connect to the account martha, and can't figure out why the
password is rejected...

> c.  Reset the ssh port forwarding for port 22  to match the new port 
> ( after rebooting the router

I don't understand that, but it sounds wrong.

> f.  No knowing if it made a difference or not, I turned off security in 
> "Preferences>>Remote Desktop"

No - it doesn't make a difference to ssh. Turn it back on.

> g.  Installed Ubuntu 10.04

Where? If on the target computer, you have certainly changed the sshd
settings, and should check them again. In fact, a default desktop
install of 10.04 does not have the ssh server installed by default! That
would explain a lot, though I'd have thought you would be seeing
"connection refused" error messages.

> h.  Deleted/reinstalled ssh from the repositories (used Synaptic if that 
> makes a difference)

Where? On the target or your local machine?

Please cut and paste an actual login attempt (obviously don't paste the
actual password or passphrase you use). We need to see what exactly you
are trying to do.

Regards, K.

Karl Auer (kauer at                   +61-2-64957160 (h)                  +61-428-957160 (mob)

GPG fingerprint: B386 7819 B227 2961 8301 C5A9 2EBC 754B CD97 0156
Old fingerprint: 07F3 1DF9 9D45 8BCD 7DD5 00CE 4A44 6A03 F43A 7DEF
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