SSH Key Problem Troubleshooting

By thomas, 5 April, 2006
I've wasted enough time with these seemingly simple tasks to warrant a quick post. The problem is that you've created keys, put the relevant files all over the place, but nothing seems to be working.
  • Permissions
    authorized_keys and authorized_keys2600
    Home Directory711
    Keys (id_dsa,id_rsa)600
    Public Keys (,
    The permissions shown are the maximum, you could put less...
  • Account locked.
    You created an account, created a key, got everything in the right location but you cannot ssh in using the key.
    If you used useradd and didn't set a password, then the acount is locked. Edit /etc/shadow and change
    user:!!: to user:*:
  • SSH Permit
    You forgot that you have an AllowUsers in /etc/ssh/sshd_config
    Add the user to AllowUsers
    AllowUsers previous users this user
    Note: this allows the users: previous; users; this; and user access to the machine
    You forgot that you have a DenyUsers in /etc/ssh/sshd_config
    Remove the user from DenyUsers
    Note: if this is your issue, you've been smoking too much weed
  • Still doesn't work, you get key-error or protocol mismatch.
    • You are using an rsa1 key on a host that supports only ssh2 (rsa and dsa keys).
      Note to self: Get with it buddy, ssh1, "what's with you man?"
    • You are using a dsa or rsa key on a host that supports only ssh1 (rsa1).