(RADIATOR) Redback is sending too many Access-Requests

[Mishari Al-Faris]

Hello Hugh,

I understand that it will "accept" and spread them randomly over 1-20 mins.
That is fine with me, as long as I treat the offending users differently
than the normal ones. My problem is that my oracle DB behind radiator can
not handle all the requests, the good and the bad ones. The bad requests are
relentless and can constitute over +95% of the incoming requests. I have
about 7500+ DSL customers and they stop complaining once I manually do
"AuthBy AllowAll" temporarily, however, I have around 200+ customers who
require static IPs obtained from the DB, and once I turn off authentication
those static-IP customers start getting dynamic IPs and start complaining,
so I can't stop authentication for long.

The amount of usernames that produce the bad requests is very small compared
to the total amount of users, say around 50+. And those are the ones I want
to exclude, also, I'm not sure what's common between them that causes them
to send so many requests. So far what I see from these users is that they
send 1 Access-Request every 1-5 seconds, consistently and without stopping,
regardless of what response I send them, Accept or Reject doesn't matter,
they keep on sending. And even when I use AllowAll, which is the fastest
response I can achieve, they still send the requests, so I'm ruling out that
the radius is slow to respond to them.

Also, the requests that come from the same user each has a different
"Acct-Session-Id". And the Redback is configured for 60 seconds timeout and
only 1 retry. So this makes me rule out that the Redback is retrying for the
same user. Instead what I think is happening is that the user connection to
the Redback is unstable and disconnecting and connecting again quickly,
which causes the Redback to create a new request for him.

So, I'm willing to try this solution even if the per-user counters take up
alot of memory, if it doesn't work I'll stop using it, but in the meantime
I'm in trouble and am willing to try anything :(

Ofcourse it goes without saying that I'm not holding any guarantees against
anyone either. If it works it works.

So what I want to do is to exclude the few users that send that many
requests and either Accept them, or Ignore them, or Reject them, doesnt
really matter, as long as I don't go to the AuthBy PLSQL clause for these
guys. hence protecting my DB from the onslaught.

On 2/1/06, Hugh Irvine <hugh at open.com.au> wrote:
>
>
> Hello Mishari -
>
> You should note first of all that this hook code will not "ignore"
> the access requests - the hook is designed to "accept" all access
> requests over a certain number with a variable session timeout that
> will cause the resulting temporary session to drop after some random
> time. The idea being to spread the requests over a longer period of
> time. Also note that this is an idea only - I make no guarantees
> about the success or otherwise of using this code.
>
> I am also not sure about maintaining per-user counters, as this will
> lead to greatly increased memory usage.
>
> Can you tell me exactly what you are wanting to do?
>
> regards
>
> Hugh
>
>
>
> On 31 Jan 2006, at 22:53, Mishari Al-Faris wrote:
>
> > Dear Hugh,
> >
> > This is an example that you suggested a while back to mitigate
> > excessive requests coming from DSL NASes.
> > I've been trying to modify it to our needs but have been getting
> > compilation errors. Let me just explain what I wish to do instead
> > of going through what I did wrong.
> >
> > I'd like to count the access trials per "user" not per "NAS". If a
> > certain username is seen trying more than say 1 request per 5
> > seconds, I want to ignore the request, and not go through my
> > AuthPLSQL AuthBy clause. Is this possible? thanks.
> >
> > # RequestHook for AuthBy INTERNAL
> > # This hook counts the number of access requests that are received
> > for a
> > # particular NAS, and returns an ACCEPT if there are more than 100
> > per second.
> > # A Session-Timeout reply attribute is added to the reply with a
> > random
> > # value between 1 and 1200 seconds(20 minutes).
> > #
> > # Note: these values should be altered as required.
> > #
> > # Hugh Irvine, Open System Consultants, 20050829
> >
> > sub
> > {
> > my $p = $_[0];
> > my $time = time;
> > my $code = $p->code;
> > my $nas = $p->{Client};
> > if ($time == $nas->{last_throttle_time} && $code eq 'Access- Request')
> > {
> > if (++$nas->{throttle_count} > 100)
> > {
> > $p->{rp}->add_attr('Session-Timeout', int (rand(1200) + 1));
> > return ($main::ACCEPT, 'Conditional flood control');
> > }
> > }
> > else
> > {
> > $nas->{throttle_count} = 0;
> > }
> > $nas->{last_throttle_time} = $time;
> > return ($main::IGNORE, 'Continue to proxy');
> > }
> >
> >
> >
> > Here is an example of how to use the hook.
> >
> >
> > <Handler .....>
> >
> > AuthByPolicy ContinueWhileIgnore
> >
> > <AuthBy INTERNAL>
> > RequestHook file:"throttle.pl"
> > AddToReply .....
> > </AuthBy>
> > # normal AuthBy
> > <AuthBy .....>
> > .....
> > </AuthBy>
> > </Handler>
>
>
> NB:
>
> Have you read the reference manual ("doc/ref.html")?
> Have you searched the mailing list archive (www.open.com.au/archives/
> radiator)?
> Have you had a quick look on Google (www.google.com)?
> Have you included a copy of your configuration file (no secrets),
> together with a trace 4 debug showing what is happening?
>
> --
> Radiator: the most portable, flexible and configurable RADIUS server
> anywhere. Available on *NIX, *BSD, Windows, MacOS X.
> -
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> -
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>
>
>
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