Please send me listing of the user id that works, and some samples of what and how you are trying to do it - showing when it works and when it does not.

Consider using the PM to keep it private.

What we see here is that a pub_key is being sent to the "other side", this public key will be used to encrypt a message that will need the private key to read (to verify that you 'own' the public key). The client (i.e. sftp) cannot read, or otherwise find the private key to decrypt the message. As such, you cannot respond to the secret message being sent (no packet sent), and system falls back on regular password authentification.

The simple things to check are: owner and mode of id_dsa file. As I recall, file mode must be 600 (rw-------) and owner as well.

As an example: minimum requirements are:

The file authorized_keys contains a list of public keys (e.g. the contents of id_dsa.pub for each known remote user or identity.
The file id_dsa.pub is the public key being sent (in debug info above) and is usually world readable.
The file id_dsa is the private key, and is meant to be only accessible by the owner (hence the rw-------, 600 perms settings). This file may also be additionaly protected by a pass phrase which must be entered to access the private key before it is used. (I changed my pass phrase in February, hence the different dates between public and private keys).
The pair of keys is sometimes referred to as a keychain.

So, basically, make sure you have at least the public and private keys in $HOME/.ssh directory, with correct owner and filemode settings, and that the public key is included the "other" sides $HOME/.ssh/authorized_keys file.
The other side will also need both id_dsa and id_dsa.pub files.

Try ssh with the -vvv option (very, very verbose) to show debugging info. Beyond that, the only thing I can suggest is to check that user3's and user4's keys are correct. To go any farther, we'll have to know your exact configuration.

Hi, going to move this to new forums - but - please give a bit more detail. What are you trying to accomplish? login without a password? remote command execution? or just logging in?