diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 371618f497..bfc8ef29f7 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -318,6 +318,9 @@ Release 2.5.0 - UNRELEASED
     HADOOP-10451. Remove unused field and imports from SaslRpcServer.
     (Benoy Antony via jing9)
 
+    HADOOP-10345. Sanitize the the inputs (groups and hosts) for the proxyuser
+    configuration. (Benoy Antony via jing9)
+
   OPTIMIZATIONS
 
   BUG FIXES 
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/authorize/ProxyUsers.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/authorize/ProxyUsers.java
index 15ddcdca13..c2029daa6b 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/authorize/ProxyUsers.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/authorize/ProxyUsers.java
@@ -70,7 +70,7 @@ public class ProxyUsers {
     String regex = CONF_HADOOP_PROXYUSER_RE+"[^.]*\\"+CONF_GROUPS;
     Map<String,String> allMatchKeys = conf.getValByRegex(regex);
     for(Entry<String, String> entry : allMatchKeys.entrySet()) {
-      Collection<String> groups = StringUtils.getStringCollection(entry.getValue());
+      Collection<String> groups = StringUtils.getTrimmedStringCollection(entry.getValue());
       proxyGroups.put(entry.getKey(), groups );
       //cache the groups. This is needed for NetGroups
       Groups.getUserToGroupsMappingService(conf).cacheGroupsAdd(
@@ -82,7 +82,7 @@ public class ProxyUsers {
     allMatchKeys = conf.getValByRegex(regex);
     for(Entry<String, String> entry : allMatchKeys.entrySet()) {
       proxyHosts.put(entry.getKey(),
-          StringUtils.getStringCollection(entry.getValue()));
+          StringUtils.getTrimmedStringCollection(entry.getValue()));
     }
     
     init = true;
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
index 9ffbe63457..e7f983ac66 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
@@ -28,9 +28,11 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Date;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Set;
 import java.util.StringTokenizer;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -351,12 +353,15 @@ public class StringUtils {
 
   /**
    * Splits a comma separated value <code>String</code>, trimming leading and trailing whitespace on each value.
+   * Duplicate and empty values are removed.
    * @param str a comma separated <String> with values
    * @return a <code>Collection</code> of <code>String</code> values
    */
   public static Collection<String> getTrimmedStringCollection(String str){
-    return new ArrayList<String>(
+    Set<String> set = new LinkedHashSet<String>(
       Arrays.asList(getTrimmedStrings(str)));
+    set.remove("");
+    return set;
   }
   
   /**
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/authorize/TestProxyUsers.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/authorize/TestProxyUsers.java
index edb9f7781d..96e7736e69 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/authorize/TestProxyUsers.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/authorize/TestProxyUsers.java
@@ -19,6 +19,7 @@ package org.apache.hadoop.security.authorize;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Collection;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -223,6 +224,41 @@ public class TestProxyUsers {
     assertNotAuthorized(proxyUserUgi, "1.2.3.5");
   }
 
+  @Test
+  public void testWithDuplicateProxyGroups() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set(
+      ProxyUsers.getProxySuperuserGroupConfKey(REAL_USER_NAME),
+      StringUtils.join(",", Arrays.asList(GROUP_NAMES,GROUP_NAMES)));
+    conf.set(
+      ProxyUsers.getProxySuperuserIpConfKey(REAL_USER_NAME),
+      PROXY_IP);
+    ProxyUsers.refreshSuperUserGroupsConfiguration(conf);
+    
+    Collection<String> groupsToBeProxied = ProxyUsers.getProxyGroups().get(
+        ProxyUsers.getProxySuperuserGroupConfKey(REAL_USER_NAME));
+    
+    assertEquals (1,groupsToBeProxied.size());
+  }
+  
+  @Test
+  public void testWithDuplicateProxyHosts() throws Exception {
+    Configuration conf = new Configuration();
+    conf.set(
+      ProxyUsers.getProxySuperuserGroupConfKey(REAL_USER_NAME),
+      StringUtils.join(",", Arrays.asList(GROUP_NAMES)));
+    conf.set(
+      ProxyUsers.getProxySuperuserIpConfKey(REAL_USER_NAME),
+      StringUtils.join(",", Arrays.asList(PROXY_IP,PROXY_IP)));
+    ProxyUsers.refreshSuperUserGroupsConfiguration(conf);
+    
+    Collection<String> hosts = ProxyUsers.getProxyHosts().get(
+        ProxyUsers.getProxySuperuserIpConfKey(REAL_USER_NAME));
+    
+    assertEquals (1,hosts.size());
+  }
+
+
   private void assertNotAuthorized(UserGroupInformation proxyUgi, String host) {
     try {
       ProxyUsers.authorize(proxyUgi, host, null);
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
index 4f06a31649..0c930d4392 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
@@ -22,9 +22,12 @@ import static org.apache.hadoop.util.StringUtils.TraditionalBinaryPrefix.long2St
 import static org.apache.hadoop.util.StringUtils.TraditionalBinaryPrefix.string2long;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -401,6 +404,14 @@ public class TestStringUtils extends UnitTestcaseTimeLimit {
       "begin %foo%_%bar%_%baz% end", pattern, replacements));
   }
 
+  @Test 
+  public void testGetUniqueNonEmptyTrimmedStrings (){
+    final String TO_SPLIT = ",foo, bar,baz,,blah,blah,bar,";
+    Collection<String> col = StringUtils.getTrimmedStringCollection(TO_SPLIT);
+    assertEquals(4, col.size());
+    assertTrue(col.containsAll(Arrays.asList(new String[]{"foo","bar","baz","blah"})));
+  }
+
   // Benchmark for StringUtils split
   public static void main(String []args) {
     final String TO_SPLIT = "foo,bar,baz,blah,blah";