If you run a linux server with with a ssh service on the TCP port 22 , you are likely to get bombarded by automated login attempt by hundreds and hundreds of bots
You can look at the file getting created by launching
tail -f /var/log/auth.log | grep Failed
the first thing you can do to stop that is to change the default port user by the SSH service on you linux server
for this you just have to edit the config file : /etc/ssh/sshd_config
Find the following lines
# What ports, IPs and protocols we listen for
And put the new port on which you would like to run your OpenSSH server.
After this little change restart the ssh service with the command
service ssh restart
You should see that the numerous and constant attacks sould instantly stop.
Security by obscurity is still security.