SSH Settings

Hardening the service you keep

SSH is almost always allowed to stay, so this is an editing job rather than a removal job. One file:

sudo nano /etc/ssh/sshd_config

Use Ctrl+W to search for each setting below, and change it to the value in the middle column. If a line starts with a #, that means it is switched off, so delete the # as well.

Save with Ctrl+O, Enter, then Ctrl+X.

💡 Check there is only one copy of each line. If the same setting appears twice in the file, the machine may not use the one you edited. After changing a line, press Ctrl+W and search for it again to make sure there is not a second one further down.

Apply the change

sudo systemctl restart ssh

If you want to be careful, check your typing first:

sudo sshd -t

That says nothing at all if the file is fine. If it complains, fix the file before restarting, because a service that will not start is a service nobody can log into.

Try it yourself

sudo nano /etc/ssh/sshd_config     # Ctrl+W to find each setting in the table
sudo sshd -t                        # silence means it is fine
sudo systemctl restart ssh