Why I cannot connect to Kafka from outside?

Question

I am running kafka on ec2 instance. So amazon ec2 instance has two ips one is internal ip and second one is for external use.

I created producer from local machine,

Answer 1

I just did this in AWS. First get the Kafka server to listen on the correct interface/IP using host.name. For your case this would be the internal IP, not localhost, since your intent is for outside Kafka clients to connect. Any local clients will need to use that same address, not localhost.

Then set advertised.host.name to a host name, not an IP address. The trick is to get that host name to always resolve to the correct IP for both internal and external machines. I use /etc/hosts inside and DNS outside. See my full answer about Kafka and name resolution here.