CentOS - Apr 2008 - CONNECTING VIA SSH BETWEEN CENTOS 4 AND 5

Hi,

I am trying to set up an automatic connection between CentOS 4 system 
(server) and a CentOS 5 DomU VM (client) via ssh to enable my to back up 
development files on the server to the client with a cron process.

I generate they key pair without a pass phrase on the client and copy 
the public key to the same user's .ssh directory on the server as 
authorized_keys2.

When I try to ssh to the Server from the Client, I am still asked for 
the user's password on the client.

If I do the same with CentOS 5 for both Client and Server, I can login 
without providing a password.

The versions of ssh on the two systems are:

Client (CentOS 5):   OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006

Server (CentOS 4):   OpenSSH_3.9p1, OpenSSL 0.9.7a Feb 19 2003

Does anyone on the list know whether these versions are compatible or 
how to get them to work together without requiring a password.

It is not an option to change to CentOS5 on the server side as that 
system is serving as a development system for a client running RedHat ES 
4 and has to have the identical configuration and be binary compatible.

TIA

ChrisG

On Wed, Apr 16, 2008 at 9:32 PM, Chris Geldenhuis
<chris.gelden at iafrica.com> wrote:
>  I generate they key pair without a pass phrase on the client and copy the
> public key to the same user's .ssh directory on the server as
> authorized_keys2.
Why not 'authorized_keys'? 'authorized_keys2' has become
deprecated
ever since SSH switched to version 2 of the protocol by default.

Take care,
Daniel

PS. You can use the '-v' flag to ssh to debug things better.

On Wed, Apr 16, 2008 at 1:32 PM, Chris Geldenhuis
<chris.gelden at iafrica.com> wrote:
> Hi,
>
>  I am trying to set up an automatic connection between CentOS 4 system
> (server) and a CentOS 5 DomU VM (client) via ssh to enable my to back up
> development files on the server to the client with a cron process.
>
>  I generate they key pair without a pass phrase on the client and copy the
> public key to the same user's .ssh directory on the server as
> authorized_keys2.
>
>  When I try to ssh to the Server from the Client, I am still asked for the
> user's password on the client.
>
>  If I do the same with CentOS 5 for both Client and Server, I can login
> without providing a password.
>
>  The versions of ssh on the two systems are:
>
>  Client (CentOS 5):   OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006
>
>  Server (CentOS 4):   OpenSSH_3.9p1, OpenSSL 0.9.7a Feb 19 2003
>
>  Does anyone on the list know whether these versions are compatible or how
> to get them to work together without requiring a password.
>
>  It is not an option to change to CentOS5 on the server side as that system
> is serving as a development system for a client running RedHat ES 4 and has
> to have the identical configuration and be binary compatible.
I know this works between the entire CentOS family. The main problems
I have seen are that the users home directory or .ssh permissions are
not secure enough for ssh to do its thing.

ssh -v -v -v will tell you more than you want on where it is having
problems.. but the quick fix I use are the following:

su - root
chown $user $user_homedir # fill in $user and $user_home correctly as
in dude and /nfs/home/d/dude
chmod 0750 $user_homedir
chown $user $user_homedir/.ssh
chmod 0700 $user_homedir/.ssh
chmod 0600 $user_homedir/.ssh/authorized_keys

If that doesn't fix the problem the -v -v -v will tel what else might
be the cause.



-- 
Stephen J Smoogen. -- CSIRT/Linux System Administrator
How far that little candle throws his beams! So shines a good deed
in a naughty world. = Shakespeare. "The Merchant of Venice"