Based on your description, how are you proposing the usernames be populated in the logs without authenticating the users?
Are you asking that the username be populated with the users information that they provided? Even if they didnt sucessfully authenticate?
I havent had the oppourtunity to try out some of the Authenticate properties on 7.x, but there is a property for 'Authenticate.RawUsername'. This may allow you to log a username, and if you are using the default configuration on 7.x with 'Authenticate and Authorize' you would just disable the 'Authorize' ruleset which would only permit certain groups to continue on.
You did not state a version, I'm assuming 7.x.
The version is 7.x (forgot to mention it).
Well, what I wish to do is authenticate users (NTLM) and permit internet access regarless authentication is sucessfully or not. Regarding logs, I wish to have user (NTLM) information (when applied) or IP/hostname.
I've managed to create an authentication exception for all user-agents that are not Mozilla and MSIE.