A man-in-the-middle (MITM) attack is a type of cyber attack where communication between two parties is intercepted using malicious tools and techniques. The MITM attacker acts as an intermediary between the two parties to monitor, modify and steal data. To protect against a MITM attack, here are some things you can do:

1. Enable two-factor authentication (2FA) to protect access to sensitive data.
2. Use secure communications tools such as VPNs and HTTPS connections.
3. Regularly update system software and applications to mitigate the risks of vulnerabilities.
4. Implement a firewall and regularly monitor it to detect unusual activity.
5. Back up your data frequently and use encryption when storing data.