Current proposal is here: https://cwiki.apache.org/confluence/display/KAFKA/Security
Here are the two open questions I am aware of: 1. We want to separate authentication and authorization. This means permissions will be assigned to some user-like subject/entity/person string that is independent of the authorization mechanism. It sounds like we agreed this could be done and we had in mind some krb-specific mangling that Gwen knew about and I think the plan was to use whatever the user chose to put in the Subject Alternative Name of the cert for ssl. So in both cases these would translate to a string denoting the entity whom we are granting permissions to in the authorization layer. We should document these in the wiki to get feedback on them. The Hadoop approach to extraction was something like this: http://docs.hortonworks.com/HDPDocuments/HDP1/HDP-1.3.1/bk_installing_manually_book/content/rpm-chap14-2-3-1.html But actually I'm not sure if just using the full kerberos principal is so bad? I.e. having the user be jenni...@athena.mit.edu versus just jennifer. Where this would make a difference would be in a case where you wanted the same user/entity to be able to authenticate via different mechanisms (Hadoop auth, kerberos, ssl) and have a single set of permissions. 2. For SASL/Kerberos we need to figure out how the communication between client and server will be handled to pass the challenge/response byte[]. I.e. http://docs.oracle.com/javase/7/docs/api/javax/security/sasl/SaslClient.html#evaluateChallenge(byte[]) http://docs.oracle.com/javase/7/docs/api/javax/security/sasl/SaslServer.html#evaluateResponse(byte[]) I am not super expert in this area but I will try to give my understanding and I'm sure someone can correct me if I am confused. Unlike SSL the transmission of this is actually outside the scope of SASL so we have to specify this. Two proposals Original Proposal: Add a new "authenticate" request/response The proposal in the original wiki was to add a new "authenticate" request/response to pass this information. This matches what was done in the kerberos implementation for zookeeper. The intention is that the client would send this request immediately after establishing a connection, in which case it acts much like a "handshake", however there is no requirement that they do so. Whether the authentication happens via SSL or via Kerberos, the effect will just be to set the username in their session. This will default to the "anybody" user. So in the default non-secure case we will just be defaulting "anybody" to have full permission. So to answer the question about whether changing user is required or not, I don't think it is but I think we kind of get it for free in this approach. In this approach there is no particular need or advantage to having a separate port for kerberos I don't think. Alternate Proposal: Create a Handshake The alternative I think Michael was proposing was to create a handshake that would happen at connection time on connections coming in on the SASL port. This would require a separate port for SASL since otherwise you wouldn't be able to tell if the bytes you were getting were for SASL or were the first request of an unauthenticated connection. Michael it would be good to work out the details of how this works. Are we just sending size-delimited byte arrays back and forth until the challenge response terminates? My Take The pro I see for Michael's proposal is that it keeps the authentication logic more localized in the socket server. I see two cons: 1. Since the handshake won't go through the normal api layer it won't go through the normal logging (e.g. request log), jmx monitoring, client trace token, correlation id, etc that we get for other requests. This could make operations a little confusing and make debugging a little harder since the client will be blocking on network requests without the normal logging. 2. This part of the protocol will be inconsistent with the rest of the Kafka protocol so it will be a little odd for client implementors as this will effectively be a request/response that they will have to implement that will be different from all the other request/responses they implement. In practice these two alternatives are not very different except that in the original proposal the bytes you send are prefixed by the normal request header fields such as the client id, correlation id, etc. Overall I would prefer this as I think it is a bit more consistent from the client's point of view. Cheers, -Jay
