Można zablokować zdalny dostęp do systemu przez SSH.

1. open /etc/sshd_conifg in your favorite text editor.

2. add the following line:

AllowUsers username1 username2

replacing username1 and 2 with the short usernames of those users who *will* be able to log in via ssh. you can add as many as you want, separated by spaces.

3. restart the ssh daemon (or, as i did, the computer)