ssh public key problem

Lotharster · 12-28-2005, 01:56 PM

I am trying to get ssh public key authenitcation to work, but I'm always greeted with a password prompt. I did the following:

1.) Created a public/private key pair via

Code:

$ ssh-keygen -b 2048 -t dsa

2.) scp'd the id_dsa.pub file to the remote server and added it to the authorized_keys file via

Code:

$ cat id_dsa.pub >>authorized_keys

3.) added the private key to my ssh-agent via

Code:

$ ssh-add

In the sshd_conf file on the remote machine, PubkeyAuthentication is set to yes, so it should work. Logging in via password authentication also works fine. So what is the poblem?

PS: This is the ssh output with the -vvv option enabled (abridged):

Code:

(...)
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/lo/.ssh/id_dsa (0x8090518)
debug2: key: /home/lo/.ssh/identity ((nil))
debug2: key: /home/lo/.ssh/id_rsa ((nil))
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: start over, passed a different list publickey,password,keyboard-interactive
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/lo/.ssh/id_dsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Trying private key: /home/lo/.ssh/identity
debug3: no such identity: /home/lo/.ssh/identity
debug1: Trying private key: /home/lo/.ssh/id_rsa
debug3: no such identity: /home/lo/.ssh/id_rsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug2: we sent a keyboard-interactive packet, wait for reply
debug2: input_userauth_info_req
debug2: input_userauth_info_req: num_prompts 1
Password:

david_ross · 12-28-2005, 03:07 PM

What are the permissions on the server files:
ls -la ~/.ssh

The directory should be 700 and the files 600.

Lotharster · 12-28-2005, 03:32 PM

The permissions are right. Could the sshd possibly block publickey access from machines outside its network? The remote server is part of the university network, and I try to login from my home. But blocking publickey access and allowing password authentication would be weird anyway.

Chowroc · 12-28-2005, 08:18 PM

from the debug info, it does not try the dsa key that you have generate:
debug1: Trying private key: /home/lo/.ssh/identity
debug3: no such identity: /home/lo/.ssh/identity
debug1: Trying private key: /home/lo/.ssh/id_rsa
debug3: no such identity: /home/lo/.ssh/id_rsa

i think you can create an id_rsa key to see if that work at first