radippool and expiry time

[Alan DeKok]

On Aug 27, 2021, at 4:17 AM, Mirko Alberio via Freeradius-Users <freeradius-users at lists.freeradius.org> wrote:
> We have this "issue":
> 
> - Our NAS are correctly configured with 10 minutes Interim-Update
> 
> - Radius has 1h lease time for radippool module
> 
> all is working fine but when simulating a NAS outage, for example it becomes disconnected from our network, IPs allocated from PPPOE users on that nas remain allocated even if expiry time is expired. Then when NAS comes back the expiry time is updated and all works fine, but our doubt is if this behaviour is intended or there is some other configuration our side: I expect that if an allocation expires because no interim update is received (and no accounting-stop is received because the NAS is not communicating) allocation should be freed, right?

  No.

  When the NAS reboots, it should send an accounting "on" packet to FreeRADIUS.  This tells FreeRADIUS that the users are all offline.  FreeRADIUS will then clear all sessions.

  If the NAS is just not sending packets, then FreeRADIUS does nothing.  i.e. there's no "cron" job which walks through the database to clean up expired entries.

  When things are working fine, the expired entries are automatically cleaned up when either the NAS sends a "stop", indicating that the session is done.  Or, when another user requests an IP, and the server notices that it can re-use the expired entries.

  So the question is, *why* would the expired entries be cleaned up, and *who* would do it?

  A related question is why is there any issue with having expired entries in the database?  Who cares if the entry has been expired, and not marked "free" ?

  Alan DeKok.