SSH known_hosts
also: known hosts file, SSH key fingerprint store
A file that stores the public keys of remote SSH servers you've connected to, allowing SSH to verify server identity and prevent man-in-the-middle attacks.
The known_hosts file is typically located at ~/.ssh/known_hosts in your home directory. When you connect to an SSH server for the first time, the server's public key is automatically added to this file after you confirm the connection. On subsequent connections, SSH compares the server's presented key against the stored entry to verify authenticity.
Each line in the file contains a hostname (or IP address), the key type, and the server's public key. For example: example.com ssh-rsa AAAAB3NzaC1yc2E...
This mechanism protects you from man-in-the-middle attacks where an attacker could intercept your connection and impersonate the server. If a server's key changes unexpectedly, SSH will warn you and refuse to connect until you manually remove or update the entry.