Re: [radext] More bad behavior

Yasin KAPLAN <> Tue, 05 September 2023 09:07 UTC

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From: Yasin KAPLAN <>
Date: Tue, 05 Sep 2023 12:06:33 +0300
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Subject: Re: [radext] More bad behavior
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There may be a couple of reasons why a RADIUS server cannot process/record
the received accounting requests as you stated. Replying with an
Error-Cause would be more useful and this should have minimum impact on
existing RADIUS client/server implementations. RADIUS clients have limited
resources to keep failed RADIUS accounting requests for retrying. Replying
with an Error-Cause would eliminate unnecessary resource usage on the
client side.

RADIUS clients should disconnect user sessions if a predefined amount of
RADIUS interim updates cannot be processed to prevent revenue loss if
RADIUS accounting is being used for billing purposes.

Some systems may implement only  RADIUS accounting so there should not be a
problem to receive and process accounting packets without authentication. A
RADIUS server can emit a disconnect request for an un-authenticated session
when a RADIUS accounting start is received without authentication if the
network policy mandates it.

On Mon, Sep 4, 2023 at 8:48 PM Alan DeKok <>

>   I might just post a weekly or monthly summary of craziness seen in the
> wild.
>   This week I've updated the Wiki:
>   Summary below:
> ## Bad packets vs Local failure
> RFC 2866 Section 2 says:
>    If the RADIUS accounting server is unable to successfully record the
>    accounting packet it MUST NOT send an Accounting-Response
>    acknowledgment to the client.
> The issue of "my DB is down" is very very different from the issue of "I
> don't know what to do with this packet. Especially if such a packet arrives
> in the middle of a stream of packets which are recorded. Failure to respond
> to one packet can cause spurious errors.
> The solution may be to reply with a Protocol-Error packet. But many
> systems don't support them.
> Or instead perhaps send an Accounting-Response with Error-Cause = ...
> unknown? So systems which support that can say "this data wasn't recorded".
> And systems which don't support it will just keep going.
> i.e. not recording bad data is likely better than failing to record good
> data, because of some ??? issue with bad data.
> ## Tying Access-Request to Accounting-Request
> Some systems may look for Access-Request packets as a "session start", and
> then refuse to record accounting packets if no prior Access-Accept was
> sent. i.e. it only sends responses for sessions it believes should exist.
> This behavior is almost always wrong.
> In a proxying / fail-over / load-balance system, some servers may not see
> Access-Request packets for a session. But the accounting data is still
> never the less OK.
> Systems should record such data for later processing.
> _______________________________________________
> radext mailing list


*Yasin KAPLAN*

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