mod_auth_kerb is an Apache module for authenticating Web clients in a
Kerberos v5 realm. Authentication may be performed via the Kerberos
principal/password; it may also be done securely using SPNEGO (HTTP
Negotiate auth protocol) to perform a GSSAPI/Kerberos authentication
from the user's browser and Kerberos credentials directly to the server
Kerberos credentials 'HTTP/host@REALM'. Because the Kerberos password is
transmitted in plain text in the former mode, when using mod_auth_kerb
for naive HTTP Basic (password-based) authentication, this module
MUST be used in conjunction with an encryption-capable Web server
(e.g. Apache) to keep that exchange private. There is no documentation
provided; see the Web site for more details.

WWW: http://modauthkerb.sourceforge.net/