Saturday, September 29, 2007

JAAS and tomcat

The JAAS ( authentication/authorization ) API has been around for many years now - the idea is to use a standard API for all authentication, and plugins to use NT, LDAP, PAM, SSO and any other realm. JAAS seems modeled after PAM - the auth API for linux ( and unix in general).

Tomcat supports JAAS auth and provides a sample LoginModule based on the simple clear-text xml file. Like most other apps using auth, tomcat also have direct modules to authenticate against DB, LDAP/JNDI, files - but it will never cover the same range of auth sources as PAM for example ( ).

JAAS has few big problems - it is quite complex, it lacks modules and it lacks users. A benefit of using a tomcat-specific module is that it can be better optimized for the target environment. The only reason to use it would be to use a PAM auth source, there is now a JAAS-PAM implementation - seems very good, LGPL, uses JNI to interface with PAM.

The default JAAS modules from Sun seem quite useless - they can authenticate the current user, not much more. The JDNI module is probably usable, but the tomcat JNDI source seems more customizable and simpler.

Another option that wraps PAM is SysAuth
(GPL2), it defines it's own simpler API, it could be wrapped in JAAS or
in a tomcat module. Due to license and the fact that jaas-pam exists -
probably not worth the effort. Another dead end is ShadowJAAS - it supports unix
user/password authentication, by parsing passwd/shadow files in a SUID
root file.