rlm_acct_unique Issue

[Tim O'Donovan]

Hi,

We're using FreeRADIUS 2.1.6, and have rlm_acct_unique configured as per
the below:

acct_unique {
	key = "User-Name, Framed-IP-Address, Acct-Session-Id"
}

Over the past couple of days we've noticed that the unique session ID
calculated by the module during interim updates is changing mid session
for some users, although none of the attributes defined in the
configuration are changing between requests.

Here's an example for a session that had started on 2009-09-06 at 00:31:28:

Mon Sep  7 05:00:23 2009
        Acct-Session-Id = "01BCBC45"
        Framed-Protocol = PPP
        Framed-IP-Address = xxx.xxx.xxx.xxx
        User-Name = "user at realm"
        Cisco-AVPair = "connect-progress=LAN Ses Up"
        Cisco-AVPair = "nas-tx-speed=7349000"
        Cisco-AVPair = "nas-rx-speed=1000"
        Acct-Session-Time = 102534
        Acct-Input-Octets = 5792373
        Acct-Output-Octets = 8666851
        Acct-Input-Packets = 79786
        Acct-Output-Packets = 54731
        Acct-Authentic = RADIUS
        Acct-Status-Type = Interim-Update
        NAS-Port-Type = Virtual
        Cisco-NAS-Port = "Uniq-Sess-ID40"
        NAS-Port = 40
        Service-Type = Framed-User
        NAS-IP-Address = xxx.xxx.xxx.xxx
        Acct-Delay-Time = 45
        Acct-Unique-Session-Id = "3c17c916d8e9ff20"
        Timestamp = 1252296023
        Request-Authenticator = Verified

Mon Sep  7 05:28:24 2009
        Acct-Session-Id = "01BCBC45"
        Framed-Protocol = PPP
        Framed-IP-Address = xxx.xxx.xxx.xxx
        User-Name = "user at realm"
        Cisco-AVPair = "connect-progress=LAN Ses Up"
        Cisco-AVPair = "nas-tx-speed=7349000"
        Cisco-AVPair = "nas-rx-speed=1000"
        Acct-Session-Time = 104260
        Acct-Input-Octets = 5895021
        Acct-Output-Octets = 8838223
        Acct-Input-Packets = 81164
        Acct-Output-Packets = 55643
        Acct-Authentic = RADIUS
        Acct-Status-Type = Interim-Update
        NAS-Port-Type = Virtual
        Cisco-NAS-Port = "Uniq-Sess-ID40"
        NAS-Port = 40
        Service-Type = Framed-User
        NAS-IP-Address = xxx.xxx.xxx.xxx
        Acct-Delay-Time = 0
        Acct-Unique-Session-Id = "fb0d91180bc7523e"
        Timestamp = 1252297704
        Request-Authenticator = Verified

I've hidden the Framed-IP-Address and User-Name attributes, but they
were identical in both requests.

Prior to 05:28:2 today, the unique session ID was always returned as
3c17c916d8e9ff20, and since 05:28:24, it has been returned as
fb0d91180bc7523e.

The only common factor with the sessions where this has happened is the
Acct-Delay-Time attribute being set to 45 in the last logged request
before the ID had changed, but I can't see any evidence on the server of
a delay, or any issues that may have caused a delay, around this time.

Does anyone know what might be causing this?


Thanks,
Tim