Hi, Thanks for the report. Can you please file a JIRA ticket?
Ismael On Thu, Oct 7, 2021 at 3:47 PM Rodolfo Kohn <rodolfo.k...@wayaga.com> wrote: > Hello, I’d like to report an error I noticed while testing Kafka with a > tool I developed to detect network issues in applications. > > When a consumer tries to connect to a Kafka broker and there is an error > in the SSL handshake, like the server sending a certificate that cannot be > validated for not matching the common name with the server/domain name, > Kafka sends out erroneous SSL messages before sending an SSL alert. This > error occurs in client but also can be seen in server. > Because of the nature of the problem it seems it will happen in more if > not all handshake errors. > I've debugged and analyzed the Kafka networking code > in org.apache.kafka.common.network and wrote a detailed description of how > the error occurs. > > I'm attaching the pcap file and a pdf with the detailed description of > where the error is in the code. > > I executed a very basic test between kafka-console-consumer and a simple > installation of one Kafka broker with TLS. > The test consisted on a Kafka broker with a certificate that didn’t match > the domain name I used to identify the server. The CA was well set up to > avoid related problems, like unknown CA error code. Thus, when the server > sends the certificate to the client, the handshake fails with code error 46 > (certificate unknown). The goal was that my tool would detect the issue and > send an event, describing a TLS handshake problem for both processes. > However, I noticed the tool sent what I thought it was the wrong event, it > sent a TLS exception event for an unexpected message instead of an event > for TLS alert for certificate unknown. > > I noticed that during handshake, after the client receives Sever Hello, > Certificate, Server Key Exchange, and Server Hello Done, it sends out the > same Client Hello it sent at the beginning and then 3 more records with all > zeroes, in two more messages. It sent a total of 16,709 Bytes including the > 289 Bytes of Client Hello record. > > > I'm working with Kafka version 2.13-2.8.0 > > Thanks! > > Rodolfo Kohn > > Wayaga LLC, Principal Consultant > > +1 (208) 206 7324 > > > https://www.linkedin.com/in/rodolfo-kohn-31032/ > > > > > >
