What is the name of the file commonly used for passwordless SSH key authentication?

The file commonly used for passwordless SSH key authentication is named authorized_keys. This file resides in the .ssh directory of a user's home folder on the remote server. It contains the public keys that are authorized to connect to the server without needing a password. When setting up SSH key-based authentication, a user generates a key pair, which consists of a private key and a public key. The public key is then placed into the authorized_keys file on the server, allowing for secure and passwordless login.

The other files mentioned serve different purposes within the SSH system. The id_dsa and id_rsa files are private key files derived from different encryption algorithms (DSA and RSA, respectively) and should be kept secure and private. Meanwhile, known_hosts is a file that stores the fingerprints of previously accessed SSH servers, allowing the client to verify the identity of the servers they connect to in the future. These files play crucial roles in the SSH security infrastructure, but they do not function in the same capacity as the authorized_keys file for facilitating passwordless authentication.