In my HDP cluster, I install 3 zookeeper-servers on 3 nodes, other nodes I just only install zookeeper-client. When I stand on Zookeeper-Server nodes, I can run zookeeper-client command OK. But when I stand on Zookeeper-Client nodes, I run zookeeper-client and can not connect to zookeeper servers 2017-03-01 23:19:57,076 - INFO [main:ZooKeeper@438] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@23ab930d Welcome to ZooKeeper! 2017-03-01 23:19:57,112 - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1019] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) JLine support is enabled 2017-03-01 23:19:57,205 - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1146] - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.net.ConnectException: Connection refused at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1125) [zk: localhost:2181(CONNECTING) 0] 2017-03-01 23:19:58,312 - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1019] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 2017-03-01 23:19:58,314 - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1146] - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.net.ConnectException: Connection refused at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1125) 2017-03-01 23:19:59,415 - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1019] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 2017-03-01 23:19:59,416 - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1146] - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.net.ConnectException: Connection refused at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1125) 2017-03-01 23:20:00,517 - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1019] - Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 2017-03-01 23:20:00,518 - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread@1146] - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.net.ConnectException: Connection refused at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1125) So anyone can have solution for this problem ... View more