17.10. Secure TCP/IP Connections with GSSAPI Encryption
Postgres Pro also has native support for using GSSAPI to encrypt client/server communications for increased security. Support requires that a GSSAPI implementation (such as MIT krb5) is installed on both client and server systems, and that support in Postgres Pro is enabled at build time.
17.10.1. Basic Setup
The Postgres Pro server will listen for both normal and GSSAPI-encrypted connections on the same TCP port, and will negotiate with any connecting client whether to use GSSAPI for encryption (and for authentication). By default, this decision is up to the client (which means it can be downgraded by an attacker); see Section 19.1 about setting up the server to require the use of GSSAPI for some or all connections.
When using GSSAPI for encryption, it is common to use GSSAPI for authentication as well, since the underlying mechanism will determine both client and server identities (according to the GSSAPI implementation) in any case. But this is not required; another Postgres Pro authentication method can be chosen to perform additional verification.
Other than configuration of the negotiation behavior, GSSAPI encryption requires no setup beyond that which is necessary for GSSAPI authentication. (For more information on configuring that, see Section 19.6.)