PostgreSQL

Trust authentication, which simply trusts that users are who they say they are.

Password authentication, which requires that users send a password.

GSSAPI authentication, which relies on a GSSAPI-compatible security library. Typically this is used to access an authentication server such as a Kerberos or Microsoft Active Directory server.

SSPI authentication, which uses a Windows-specific protocol similar to GSSAPI.

Ident authentication, which relies on an “[.quote]#Identification Protocol”# (RFC 1413) service on the client’s machine. (On local Unix-socket connections, this is treated as peer authentication.)

Peer authentication, which relies on operating system facilities to identify the process at the other end of a local connection. This is not supported for remote connections.

LDAP authentication, which relies on an LDAP authentication server.

RADIUS authentication, which relies on a RADIUS authentication server.

Certificate authentication, which requires an SSL connection and authenticates users by checking the SSL certificate they send.

PAM authentication, which relies on a PAM (Pluggable Authentication Modules) library.

BSD authentication, which relies on the BSD Authentication framework (currently available only on OpenBSD).