Essential CVS

The kserver Access Method

The kserver method is used to connect using Kerberos 4. If you do not have an existing Kerberos 4 installation on your CVS repository server, I recommend you use Kerberos 5. Kerberos 4 has known weaknesses that Kerberos 5 resolves. This section assumes that you have an existing Kerberos 4 installation and the documentation to configure and use it.

Tip

Kerberos 4 is a reasonably secure authentication system, but it has known flaws. Kerberos 5 fixes some of them; most critically, it prevents a replay attack. In Kerberos 4, there is a five-minute window in which an attacker can sniff an authentication request, modify and re-send it, and get an authentication ticket. Kerberos 5 allows only one ticket to be produced per request.

The repository path format for Kerberos is:

:kserver:[user@]hostname[:[port]]/path

The default port for kserver is 1999. If user is not specified, the client sends the username of the calling user on the client computer.

The CVS client and server must both be compiled to run Kerberos 4. If you intend to encrypt the data stream, you also need to have encryption enabled at compile time. You can test whether your CVS program has compiled kserver support by checking the command list, as shown in Example 8-11.

Example 8-11. Testing for kserver mode

bash-2.05a$ cvs --help-commands
CVS commands are:
.
.
.
        kserver      Kerberos server mode
.
.
.
(Specify the --help option for a list of other help options)

You can test for encryption support by checking ...