What methods can be used for authentication in SSH?

SSH authentication can be performed using the following main methods:

1. Password authentication — the user enters a password to access the server.
2. Public Key Authentication — a pair of keys is used: a private key stored on the client, and a public key on the server. During connection, the keys are verified for correspondence.
3. Kerberos authentication — integration with Kerberos for single sign-on (SSO).
4. X.509 certificate authentication — less common, but possible.

In practice, key-based authentication is most often used because it is more secure and convenient for automation.

Example of setting up key-based authentication:

# Generate a key on the client
ssh-keygen -t rsa -b 4096

# Copy the public key to the server
ssh-copy-id user@server

# Connect to the server
ssh user@server