PostgreSQL Administrator's Guide
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# Kerberos Authentication

Kerberos is an industry-standard secure authentication system suitable for distributed computing over a public network.

## Availability

The Kerberos authentication system is not distributed with Postgres. Versions of Kerberos are typically available as optional software from operating system vendors. In addition, a source code distribution may be obtained through MIT Project Athena.

> Note: You may wish to obtain the MIT version even if your vendor provides a version, since some vendor ports have been deliberately crippled or rendered non-interoperable with the MIT version.

Users located outside the United States of America and Canada are warned that distribution of the actual encryption code in Kerberos is restricted by U. S. Government export regulations.

Inquiries regarding your Kerberos should be directed to your vendor or MIT Project Athena. Note that FAQLs (Frequently-Asked Questions Lists) are periodically posted to the Kerberos mailing list (send mail to subscribe), and USENET news group.

## Installation

Installation of Kerberos itself is covered in detail in the Kerberos Installation Notes . Make sure that the server key file (the `srvtab` or `keytab`) is somehow readable by the Postgres account.

Postgres and its clients can be compiled to use either Version 4 or Version 5 of the MIT Kerberos protocols by setting the `KRBVERS` variable in the file `src/Makefile.global` to the appropriate value. You can also change the location where Postgres expects to find the associated libraries, header files and its own server key file.

After compilation is complete, Postgres must be registered as a Kerberos service. See the Kerberos Operations Notes and related manual pages for more details on registering services.

## Operation

After initial installation, Postgres should operate in all ways as a normal Kerberos service. For details on the use of authentication, see the PostgreSQL User's Guide reference sections for postmaster and psql.

In the Kerberos Version 5 hooks, the following assumptions are made about user and service naming:

- User principal names (anames) are assumed to contain the actual Unix/Postgres user name in the first component.

- The Postgres service is assumed to be have two components, the service name and a hostname, canonicalized as in Version 4 (i.e., with all domain suffixes removed).

Table 3-1. Kerberos Parameter Examples

Parameter | Example
--- | ---
user | frew@S2K.ORG
user | aoki/HOST=miyu.S2K.Berkeley.EDU@S2K.ORG
host | postgres_dbms/ucbvax@S2K.ORG

Support for Version 4 will disappear sometime after the production release of Version 5 by MIT.

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