How to Prevent SSH Brute Force Login Attacks

It is never a good thing when malicious actors try to gain unauthorized access to any system. SSH brute force attacks are one of the most common attacks targeting Linux systems, and must be taken seriously in order to protect any sensitive information from being compromised.

Here are some tips to help you protect your system from this type of attack:

Limit Access to Your Server

The most important step to take is to ensure that the server is only accessible to authorized users. This includes limiting the number of users with access, using strong passwords and two-factor authentication, and setting up IP filtering or whitelisting to allow access only from trusted IP addresses.

Disable Password Authentication

One of the most effective ways to prevent SSH brute force attacks is to disable password authentication and rely on key-based authentication instead. This helps to ensure that even if an attacker manages to crack the password used, they will still not be able to gain access to the server.

Reduce the Login Grace Time

By default, SSH servers are set up to wait for 60 seconds before it denies a login attempt. This gives hackers a longer time to guess passwords. You should reduce this grace time to 1-2 seconds to reduce the amount of time an attacker can have to guess passwords and make multiple attempts.

Use Lower Login Retry Limits

SSH servers are also configured to allow a certain number of login attempts before it blocks the IP address. You should lower this limits as much as possible, as this will significantly reduce the number of attempts an attacker can make before being blocked.

Enable Auditing

Enabling audit logs and system monitoring helps to ensure that any anomalies are quickly identified and addressed. This helps to identify if any malicious attempts were made, allowing you to take swift action before any sensitive information is taken.

Conclusion

SSH brute force attacks are one of the most common threats to Linux systems, and must be taken seriously. By following the steps outlined above, you will greatly reduce the chances of your system being compromised and protect any sensitive data stored on the server.