1) The listener version
2) Whether the listener password is set
3) Whether ADMIN_RESTRICTIONS are set
4) Whether listener logging is on and
5) Whether LOCAL_OS_AUTHENTICATION is on or off.
The tool also includes a set of FNDFS Oracle Applications 11i listener checks. Oracle Applications includes a seperate listener, defaulted on port 1626 in addition to the database listener. This listener is an Oracle 8.0.6 listener.
The tool also includes a SID enumeration tool and also a TNSNAMES.ORA security check. Also if you dig deep and venture to the about page you are rewarded with an extra link that takes you to a page that can be used to generate TNS names entries, 10g connect strings (the new short ones) and JDBC connect strings.
I have updated my Oracle security tools page and you can download the Oracle database listener check tool from Integrigy.