On Nov 3, 2022, at 1:56 PM, norbert.kunth@now-it.de wrote:

we recently updated from 2.1.1 to 3.0.25 (we use still 3.0.25 because it is build in our SLES distribution).

That's good.

Freeradius uses LDAP to check users. If many users login at a time we see some error messages.

To track this down we installed an internal test system that can send a lot of requests to the radius server (with radtest).

We do see some problems, but the messages (and the behavior) are not the same.

If we fire 60 requests in a short time from the test system to the servers, the server loggs: Thu Nov 3 13:35:11 2022 : Error: (159) Ignoring duplicate packet from client test port 46673 - ID: 65 due to unfinished request in component <core> module <queue>

That's bad. This message means that something is blocking the server. Seeing as the server can do 20K packets/s in a default configuration, the problem is something on your local system. i.e. slow database, network, etc.

This seems not very bad: every user is still accepted via LDAP

But in real the message is different: Thu Nov 3 00:59:25 2022 : Error: Received conflicting packet from client nas port 40634 - ID: 90 due to unfinished request in module ldap. Giving up on old request. Thu Nov 3 00:59:25 2022 : WARNING: (338542) WARNING: Module rlm_ldap became unblocked Thu Nov 3 00:59:25 2022 : Auth: (338542) Invalid user: [user024] (from client nas port 0)

Fix your database so that it replies

We think, we have a timing issue with our LDAP. But why is the log message so different?

It's the difference between the NAS retrying the same packet (duplicate), or giving up on that packet, and sending a new one for a different user (conflicting). But the error message is irrelevant. The problem is that your database is completely broken. There is simply no reason for your database to *block* for 5-30 seconds at a time. This is a *disaster*. No amount of poking FreeRADIUS will fix this. Alan DeKok.