Can I run a shell command after an authentication session?

[Kun Niu]

Dear all,

I have a freeradius server on Debian3.1.
And I have a shell command to execute after an authentication session.
In fact, I want to limit the time of user connection.
I know that it's not freeradius' job.
So I want to write a shell command for private use.
I just wonder if I can communicate with freeradius with a dependent script.

Thanks for your attention and look forward to your reply.

Sincerely,
Kun