<<< some of our clients uses oAuth and some uses cert based auth
Hi Senthil.  Brokers support different clients using different types
of authentication, so there is no problem here.  The way it works is
via the broker's listener -- each one listens on a separate port and
is either a SSL listener (mutual cert authentication), a SASL listener
(or which there are two styles, with and without encryption -- more on
that below), or a PLAINTEXT listener (no authentication).  One thing
to clarify is that any particular client cannot authenticate with
multiple identities -- Kafka does not support multiple identities on a
single session -- so if the client connects on the port associated
with SASL then the broker will ignore any client-side certificate.  As
mentioned, there are two types of listeners associated with SASL: one
called SASL_PLAINTEXT where the communication happens in the clear and
another called SASL_SSL where the communication is TLS-encrypted.  It
is this second case -- SASL_SSL -- where the client could potentially
present a certificate, but the broker ignores it in this case even if
the broker's config says it is required.  This is done because of the
constraint mentioned above -- a particular client can authenticate
with at most 1 identity over any single connection.

I hope this helps.  You may find the blog post at
https://www.confluent.io/blog/kafka-listeners-explained to be
interesting and helpful, too.

Ron

On Wed, Jan 22, 2020 at 2:07 AM Senthilnathan Muthusamy
<senth...@microsoft.com.invalid> wrote:
>
> Hi,
>
> We want both SASL (oAuthBearer) & SSL authentication to be enabled. However 
> based on the below doc, the SSL auth will be disabled if SASL is enabled.
>
> https://docs.confluent.io/current/kafka/authentication_ssl.html#brokers
>
>
> If any SASL authentication mechanisms are enabled for a given listener, then 
> SSL client authentication is disabled-even if you have specified 
> ssl.client.auth=required and the broker authenticates clients only using SASL 
> on that listener.
>
> How can we have both SASL & SSL authentication enabled as some of our clients 
> uses oAuth and some uses cert based auth?
>
> Appreciate any pointers.
>
> Thanks,
> Senthil

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