SSH Keys – How to Fix Authentication Asking for Password

linuxsolarissshssh-keys

Im trying to set access from ServerA(SunOS) to ServerB(Some custom Linux with Keyboard Interactive login) with SSH Keys. As a proof of concept I was able to do it between 2 virtual machines. Now in my real life scenario it isnt working.

I created the keys in ServerA, copied them to ServerB, chmod'd .ssh folders to 700 on both ServerA,B.

Here is the log of what I get.

    debug1: SSH2_MSG_KEXINIT sent
    debug1: SSH2_MSG_KEXINIT received
    debug1: kex: server->client aes128-ctr hmac-md5 none
    debug1: kex: client->server aes128-ctr hmac-md5 none
    debug1: Peer sent proposed langtags, ctos:
    debug1: Peer sent proposed langtags, stoc:
    debug1: We proposed langtags, ctos: en-US
    debug1: We proposed langtags, stoc: en-US
    debug1: SSH2_MSG_KEX_DH_GEX_REQUEST sent
    debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
    debug1: dh_gen_key: priv key bits set: 125/256
    debug1: bits set: 1039/2048
    debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
    debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
    debug1: Host 'XXX.XXX.XXX.XXX' is known and matches the RSA host key.
    debug1: Found key in /XXX/.ssh/known_hosts:1
    debug1: bits set: 1061/2048
    debug1: ssh_rsa_verify: signature correct
    debug1: newkeys: mode 1
    debug1: set_newkeys: setting new keys for 'out' mode
    debug1: SSH2_MSG_NEWKEYS sent
    debug1: expecting SSH2_MSG_NEWKEYS
    debug1: newkeys: mode 0
    debug1: set_newkeys: setting new keys for 'in' mode
    debug1: SSH2_MSG_NEWKEYS received
    debug1: done: ssh_kex2.
    debug1: send SSH2_MSG_SERVICE_REQUEST
    debug1: got SSH2_MSG_SERVICE_ACCEPT
    debug1: Authentications that can continue: publickey,keyboard-interactive
    debug1: Next authentication method: publickey
    debug1: Trying private key: /XXXX/.ssh/identity
    debug1: Trying public key: /xxx/.ssh/id_rsa
    debug1: Authentications that can continue: publickey,keyboard-interactive
    debug1: Trying private key: /xxx/.ssh/id_dsa
    debug1: Next authentication method: keyboard-interactive
    Password:
    Password:

ServerB has pretty limited actions since its a custom propietary linux.

What could be happening?

EDIT WITH ANSWER:

Problem was that I didnt have those settings enabled in the sshd_config (Refer to accepted answer) AND that while pasting the key from ServerA to ServerB it would interpret the key as 3 separate lines.

What I did was, in case you cant use ssh-copy-id like I couldnt. Paste the first line of your key in your "ServerB" authorized_keys file WITHOUT the last 2 characters, then type yourself the missing characters from line 1 and the first one from line 2, this will prevent adding a "new line" between the first and second line of the key. Repeat with the 3d line.

Best Answer

I don't think your keys have been properly copied, if you have ssh-copy-id available I would recommend you use that.

$ ssh-copy-id user@remote_server
Password:

Once you have entered the password, your SSH key will be copied over and you should be able to just ssh without providing the password again.

Also check your SSH configuration on ServerB and check a couple of things.

$ vi /etc/ssh/sshd_config

Another thing is to check these settings:

RSAAuthentication yes
PubKeyAuthentication yes
AuthorizedKeysFile %h/.ssh/authorized_keys

The value of AuthorizedKeysFile is where you need to paste your public ssh key.

You can collect your SSH-Key information by using: ssh-add -L

Updated

When ssh-copy-id doesn't exist you can do the old way:

$ cat ~/.ssh/id_rsa.pub | ssh user@remote_host 'cat >> /home/user/.ssh/authorized_keys'
Related Topic