[keycloak-dev] Rate Limiting Logins

Stian Thorgersen sthorger at redhat.com
Wed Sep 7 08:30:17 EDT 2016

Problem is that it would only cover one very specific issue, while still
being a relatively big thing to implement and test. There's clustering to
consider as all nodes would need to share the knowledge about number of
attempts. Also, the feature itself could end up being a DoS/OOM issue. If
there's 100 clients and 100k users that's potentially 10 million entries.

In summary trying to add this level of protection directly to Keycloak
would be very costly and most likely would never be on par with a decent

On 6 September 2016 at 15:14, Cory Snyder <csnyder at iland.com> wrote:

> Hey Stian,
> I agree that we could make something work with a Firewall / intrusion
> detection system if it’s decided that this is too complex to add directly
> to Keycloak.
> What I had in mind was a configurable sliding-time window rate limit that
> would prevent a client from making too many requests for a particular user
> in short time frames. E.g. limit each client to making at most 1 login
> request within a sliding 5 sec interval for each user. The 5 sec timespan
> could be made configurable or even be computed relative to the token
> timeout settings.

> Perhaps another alternative is to offer an admin alert to ensure that
> Keycloak admins are aware of clients that are incorrectly using/abusing the
> authentication workflow. I guess it could work the same way as the blocking
> rate limit, with the exception of the fact that it would just send an email
> to the Keycloak admin instead of directly blocking the offending client.
> The OOM was indeed our fault as we were not using the paging options, I
> just mentioned it to provide additional context for the scenario that we
> experienced and to explain the reason that we had some down-time based upon
> these excessive logins.
> All that said, perhaps you’re right about the fact that this may be better
> handled in logic external to Keycloak. In any case, I think its a
> worthwhile discussion and appreciate your input!
> Thanks,
> Cory Snyder
> On Sep 5, 2016, at 2:42 AM, Stian Thorgersen <sthorger at redhat.com> wrote:
> The brute force protection is there only to prevent guessing the password
> through a brute force attack. It's not there to stop DOS attacks. We don't
> have any rate limiting at the moment and I believe that's something that
> would be better introduced with a firewall / intrusion detection system.
> It's non-trivial to add, especially with the fact that a single client
> that invokes the direct grant login could have thousands of legitimate
> users. I don't think a simple implementation would be much value and not
> replace a full fledged firewall.
> What did you have in mind with regards to requirements? Ability to
> configure max number of requests per-client? Per-user?
> For the OOM the events endpoints supports pagination as well as date
> ranges which should prevent and OOM issue when querying it.
> On 2 September 2016 at 15:44, Cory Snyder <csnyder at iland.com> wrote:
>> Hey guys,
>> We ran into an issue recently where a customer didn’t have a great
>> understanding of the OAuth2 authorization process and was submitting many
>> direct grant login requests per second. They were successfully
>> authenticating each time, so the brute force protection features don’t
>> apply. It basically ended up being a DOS issue. We also ended up having OOM
>> issues when trying to query the events for this customer during a scheduled
>> job that we use to build reports on login events. We’re still running 1.8.2
>> at the moment, so I’m wondering if you guys have implemented any kind of
>> rate limiting / DOS prevention that could have prevented this in one of the
>> later releases? If not, I'm proposing that it might be worth considering, I
>> could try to contribute something if you like. What do you guys think?
>> Thanks,
>> Cory Snyder
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