From d799fbe1ccf8752c44f087e34b5f400591d3b5bd Mon Sep 17 00:00:00 2001
From: Yongjun Zhang <yzhang@cloudera.com>
Date: Sun, 8 Mar 2015 20:39:46 -0700
Subject: [PATCH] HDFS-7857. Improve authentication failure WARN message to
 avoid user confusion. Contributed by Yongjun Zhang.

---
 .../src/main/java/org/apache/hadoop/ipc/Server.java      | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
index 893e0eb8903..d2d61b398d3 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
@@ -1324,10 +1324,15 @@ public abstract class Server {
           saslResponse = processSaslMessage(saslMessage);
         } catch (IOException e) {
           rpcMetrics.incrAuthenticationFailures();
+          if (LOG.isDebugEnabled()) {
+            LOG.debug(StringUtils.stringifyException(e));
+          }
           // attempting user could be null
+          IOException tce = (IOException) getTrueCause(e);
           AUDITLOG.warn(AUTH_FAILED_FOR + this.toString() + ":"
-              + attemptingUser + " (" + e.getLocalizedMessage() + ")");
-          throw (IOException) getTrueCause(e);
+              + attemptingUser + " (" + e.getLocalizedMessage()
+              + ") with true cause: (" + tce.getLocalizedMessage() + ")");
+          throw tce;
         }
         
         if (saslServer != null && saslServer.isComplete()) {