To disable ssh warning message we need to add LogLevel to quiet in $HOME/.ssh/config file.
We can also diable warning messages with ssh command as shown below:
$ ssh -o LogLevel=quiet 192.168.1.10
With following example we can also disable Host Key Checking, set known hosts file to null and disable logging:
$ ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o LogLevel=quiet 192.168.1.20
ssh-keygen command is used to remove offending key entries from .ssh/known_hosts
Syntax to remove offending key of a host:
$ ssh-keygen -R hostName/IP_Address
$ ssh-keygen -R test.example.com
Above example will remove ssh key associated with hostname test.example.com
$ ssh-keygen -R 192.168.1.10
This example will remove ssh key associated with IP Address 192.168.1.10
Its always better to disable ssh access to root user which will protect the server from any attacks. Its kind of additional security layer on top of firewall.
There are 2 ways to disable SSH access to root.
In /etc/ssh/sshd_config file search for line DenyUsers, if it exists edit it as follows else add following line:
If you want to disable ssh login for multiple users on the server add as following:
DenyUsers root user1 user2 user3
After updating sshd_config add restart sshd service with following command:
$ service sshd restart
Now try to ssh to root, it should not allow login even though you entered right password.
PermitRootLogin will support 2 options “yes” and “no”.
Option yes will allow ssh to root and option no wont allow ssh to root.
To allow ssh to root add following line in /etc/ssh/sshd_config file and restart sshd service:
To disable ssh to root add following line in /etc/ssh/sshd_config file and restart sshd service: