To prevent SSH logins as root, edit this file: #vi /etc/ssh/sshd_config Set PermitRootLogin to no as follows. PermitRootLogin no Then restart SSH by typing: #service sshd restart Stopping sshd: [ OK ] Starting sshd: [ OK ] After this change, direct root login is no longer possible. Log in as another user first, then use su to become root by typing: #su - root
An SSH connection may fail with no matching host key type found when a newer client disables ssh-rsa and ssh-dss. These options configure compatibility.
If SSH to a Debian/Ubuntu server returns no hostkey alg, the SSH client failed the host key algorithm check while connecting. To fix it, check permissions…
If connecting to a server over SSH fails with "no hostkey alg", as in the example below: debug1: Reading configuration data /etc/ssh_config debug1: Connecting to 192.168.1.1 [192.168.1.1] port 22.
