'ubuntu 20.04 brute force

I am using ubuntu 20.04. When I looked at the auth.log records, I saw that there were many attempts. What security measures can be taken here.

I don't have any previous experience in this field. Security issues are very new to me. I am open to anything you suggest.

Solution 1:^[1]

Here are a few recommendations assuming that you are talking about SSH:

Disable login access to root: disable-root-login
Enable public key authentication and disable password based auth: public-key-authentication
Add IP whitelisting, using a firewall such as ufw to ensure people can only access from your IP address

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Solution	Source
Solution 1	Nick Lauder