1)In centos7, rencently ,when I use command like 'nc localhost 44444' , it show message like 'Ncat: Connection refused', after I resolved it , I find it would not response ,finally , I use 'ncat localhost 44444' and it worked.
2)when I use avro as sink in machine whose name is hadoop2, I make 'a1.sinks.k1.hostname = hadoop3 ' . Then in hadoop3, I use avro as source like 'a1.sources.r1.bind = localhost', use 'ncat localhost 44444' in hadoop2, hadoop3 didn't response. finally ,I found , it must make it 'a1.sources.r1.bind = hadoop3' in hadoop3. That is to say, sources must exactly the same with its sink