SuSE Linux: Version 7.2
This article refers to an older version of SuSE Linux.
Therefore some of the informations given in this article may
be outdated or the article may contain stale links.
OpenSSH: Version 2.9p1
OpenSSH version 2.9p1 or higher does no longer use the SSH protocol 1 but protocol 2 by default. Since older keys are not suitable for this protocol, SSH cannot authenticate users on the basis of their keys.
If you have disabled the password authentication, the authentication process will even completely abort.
There are two ways of restoring this accustomed function:
Add the following line to the already active options in the file /etc/ssh/ssh_config (to make it work on the whole computer) or in the file ~/.ssh/config (to make it work for particular users only):
Protocol 1,2
Alternatively, you can also generate new keys for the protocol 2, which is a much more secure method:
The new keys can be generated by executing ssh-keygen followed by the option for the algorithm DSA or RSA (just select the one you consider safer):
ssh-keygen -t dsaor
ssh-keygen -t rsa
The new keys can be found in the directory ~/.ssh/ after having executed ssh-keygen:
id_dsa and id_dsa.pub or id_rsa and id_rsa.pub. You should move the public keys (ending with *.pub) to the file ~/.ssh/authorized_keys2 so that they can be used, too.