Accounting for nonexistent users / NAS ?

[Phil Mayers]

On 14/02/12 10:59, justin76 at mac.com wrote:
> Thanks, i haven't used preacct before, in what module is this, can
> you send detailed solution? Sorry, i am only a beginner in writing
> customized things for freeradius.

This is a section in the standard virtual server config. If you look in 
sites-enabled/default, you'll see:

authorize {
   ...
}
authenticate {
   ...
}
post-auth {
   ...
}

preacct {
   ...
}
accounting {
   ...
}

...and others. The sections are lists of modules, or "unlang" config 
processing statements. See "man unlang".

>
> About the NAS: in our case, the client is in posession of the shared
> secret, but the NAS is set incorrectly. Also, we are using a global
> user database for hundreds of NAS clients, and we would like to avoid
> a situation when a NAS client is sending accounting information for
> an existing user as a hacker attempt, causing invalid usage data and
> causing users account to expire. In case the existing user is
> configured as a local user AND the hacker knows that a username
> exists in our radcheck table (or just use a username list for
> guessing), this can be easily done.

I'm sorry, I don't understand any of that.

If the NAS is "set incorrectly" why not fix the NAS?