问题现象

HDFS Client访问Server出现如下异常：

...
Caused by: javax.security.sasl.SaslException: No common protection layer between client and server
    at com.sun.security.sasl.gsskerb.GssKrb5Client.doFinalHandshake(GssKrb5Client.java:251)
    at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:186)
    at org.apache.hadoop.security.SaslRpcClient.saslEvaluateToken(SaslRpcClient.java:483)
    at org.apache.hadoop.security.SaslRpcClient.saslConnect(SaslRpcClient.java:427)
    at org.apache.hadoop.ipc.Client$Connection.setupSaslConnection(Client.java:552)
    at org.apache.hadoop.ipc.Client$Connection.access$1800(Client.java:367)
    at org.apache.hadoop.ipc.Client$Connection$2.run(Client.java:717)
    at org.apache.hadoop.ipc.Client$Connection$2.run(Client.java:713)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:422)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
    at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:712)
    ... 34 more

可能原因

该异常由服务端与客户端配置项hadoop.rpc.protection不一致导致。

问题解决方案

修正服务端或客户端hadoop.rpc.protection配置，确保两端一致。如修改服务端需重启服务。