PostgreSQL has native support for using SSL connections to encrypt client/server communications for increased security. This requires OpenSSL be installed on both client and server systems and support enabled at build time (see Chapter 1).
With SSL support compiled
in, the PostgreSQL server can be
started with SSL support by
setting the parameter ssl to on in
postgresql.conf. When starting in
SSL mode, the server will look
for the files server.key and server.crt in the data directory. These files
should contain the server private key and certificate
respectively. These files must be set up correctly before an
SSL-enabled server can start.
If the private key is protected with a passphrase, the server
will prompt for the passphrase and will not start until it has
been entered.
The server will listen for both standard and SSL connections on the same TCP/IP port, and will negotiate with any connecting client on whether to use SSL. See Chapter 6 about how to force the server to require use of SSL for certain connections.
For details on how to create your server private key and certificate, refer to the OpenSSL documentation. A simple self-signed certificate can be used to get started for testing, but a certificate signed by a certificate authority (CA) (either one of the global CAs or a local one) should be used in production so the client can verify the server's identity. To create a quick self-signed certificate, use the following OpenSSL command:
openssl req -new -text -out server.req
Fill out the information that openssl asks for. Make sure that you enter the local host name as Common Name; the challenge password can be left blank. The script will generate a key that is passphrase protected; it will not accept a passphrase that is less than four characters long. To remove the passphrase (as you must if you want automatic start-up of the server), run the commands
openssl rsa -in privkey.pem -out server.key rm privkey.pem
Enter the old passphrase to unlock the existing key. Now do
openssl req -x509 -in server.req -text -key server.key -out server.crt chmod og-rwx server.key
to turn the certificate into a self-signed certificate and to copy the key and certificate to where the server will look for them.