How to setup cross realm trust between two MIT KDC – In this post, we will see how to setup cross realm trust between two MIT KDC. We can access and copy data from one cluster to another if the cross realm trust is setup correctly. . In our example, we have 2 clusters with same HDP version(2.4.2.0) and Ambari version(2.2.2.0) . Cluster 1: 172.26.68.47 hwx-1.hwx.com  hwx-1 172.26.68.46 hwx-2.hwx.com  hwx-2 172.26.68.45 hwx-3.hwx.com  hwx-3 Cluster 2: 172.26.68.48 support-1.support.com support-1 172.26.68.49 support-2.support.com support-2 172.26.68.50 support-3.support.com support-3 . Below are the steps: . Step 1: Make sure both the clusters are kerberized with MIT KDC. You can use below automated script for configuring Kerberos on HDP. https://community.hortonworks.com/articles/29203/automated-kerberos-installation-and-configuration.html . Step 2: Please configure /etc/hosts file on both the clusters to have Ip <-> hostname mappings. Example: On both clusters /etc/hosts file should look like below: 172.26.68.47 hwx-1.hwx.com  hwx-1 172.26.68.46 hwx-2.hwx.com  hwx-2 172.26.68.45 hwx-3.hwx.com  hwx-3 172.26.68.48 support-1.support.com support-1 172.26.68.49 support-2.support.com support-2 172.26.68.50 support-3.support.com support-3 . Step 3: Configure krb5.conf: . 3.1 Configure [realm] section to add another cluster’s KDC server details – This is required to find KDC to authenticate user which belongs to another cluster. Example on Cluster1: [realms]   HWX.COM = {     admin_server = hwx-1.hwx.com     kdc = hwx-1.hwx.com   }   SUPPORT.COM = {     admin_server = support-1.support.com kdc = support-1.support.com } . 3.2 Configure [domain_realm] section to add another cluster’s domain <-> realm mapping. [domain_realm]   .hwx.com = HWX.COM   hwx.com = HWX.COM   .support.com = SUPPORT.COM   support.com = SUPPORT.COM . 3.3 Configure [capaths] to add another cluster’s realm [capaths]     HWX.COM = {          SUPPORT.COM = .     } On Cluster 1, the krb5.conf should look like below: [libdefaults]   renew_lifetime = 7d   forwardable = true   default_realm = HWX.COM   ticket_lifetime = 24h   dns_lookup_realm = false   dns_lookup_kdc = false   #default_tgs_enctypes = aes des3-cbc-sha1 rc4 des-cbc-md5   #default_tkt_enctypes = aes des3-cbc-sha1 rc4 des-cbc-md5 [logging]   default = FILE:/var/log/krb5kdc.log   admin_server = FILE:/var/log/kadmind.log   kdc = FILE:/var/log/krb5kdc.log [realms]   HWX.COM = {     admin_server = hwx-1.hwx.com     kdc = hwx-1.hwx.com   }   SUPPORT.COM = {     admin_server = support-1.support.com     kdc = support-1.support.com   } [domain_realm]   .hwx.com = HWX.COM   hwx.com = HWX.COM   .support.com = SUPPORT.COM   support.com = SUPPORT.COM [capaths]     HWX.COM = {          SUPPORT.COM = .     } Note – Please copy modified /etc/krb5.conf to all the nodes in Cluster 1 . Similarly on Cluster2, the krb5.conf should look like below: [libdefaults]   renew_lifetime = 7d   forwardable = true   default_realm = SUPPORT.COM   ticket_lifetime = 24h   dns_lookup_realm = false   dns_lookup_kdc = false   #default_tgs_enctypes = aes des3-cbc-sha1 rc4 des-cbc-md5   #default_tkt_enctypes = aes des3-cbc-sha1 rc4 des-cbc-md5 [logging]   default = FILE:/var/log/krb5kdc.log   admin_server = FILE:/var/log/kadmind.log   kdc = FILE:/var/log/krb5kdc.log [realms]   SUPPORT.COM = {     admin_server = support-1.support.com     kdc = support-1.support.com   }   HWX.COM = {     admin_server = hwx-1.hwx.com     kdc = hwx-1.hwx.com   } [domain_realm]   .hwx.com = HWX.COM   hwx.com = HWX.COM   .support.com = SUPPORT.COM   support.com = SUPPORT.COM [capaths]     SUPPORT.COM = {         HWX.COM = .     } Note – Please copy modified /etc/krb5.conf to all the nodes in Cluster 2 . Step 4: Modify below property in hdfs-site.xml on a cluster from where you want to execute distcp command ( specifically speaking - client side ) dfs.namenode.kerberos.principal.pattern=* . Step 5: Add a common trust principal in both the KDCs. Please keep same password for both the principals . On Cluster 1 and 2, execute below commands in kadmin utility: addprinc krbtgt/HWX.COM@SUPPORT.COM addprinc krbtgt/SUPPORT.COM@HWX.COM . Step 6: Configure auth_to_local rules on both the clusters: . On Cluster1, append auth_to_local rules from Cluster2 Example on Cluster 1: RULE:[1:$1@$0](ambari-qa-hadoop@HWX.COM)s/.*/ambari-qa/ RULE:[1:$1@$0](hdfs-hadoop@HWX.COM)s/.*/hdfs/ RULE:[1:$1@$0](spark-hadoop@HWX.COM)s/.*/spark/ RULE:[1:$1@$0](.*@HWX.COM)s/@.*// RULE:[2:$1@$0](dn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](hive@HWX.COM)s/.*/hive/ RULE:[2:$1@$0](jhs@HWX.COM)s/.*/mapred/ RULE:[2:$1@$0](jn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](nm@HWX.COM)s/.*/yarn/ RULE:[2:$1@$0](nn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](rm@HWX.COM)s/.*/yarn/ RULE:[2:$1@$0](yarn@HWX.COM)s/.*/yarn/ DEFAULT RULE:[1:$1@$0](ambari-qa-support@SUPPORT.COM)s/.*/ambari-qa/ RULE:[1:$1@$0](hdfs-support@SUPPORT.COM)s/.*/hdfs/ RULE:[1:$1@$0](spark-support@SUPPORT.COM)s/.*/spark/ RULE:[1:$1@$0](.*@SUPPORT.COM)s/@.*// RULE:[2:$1@$0](dn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](hive@SUPPORT.COM)s/.*/hive/ RULE:[2:$1@$0](jhs@SUPPORT.COM)s/.*/mapred/ RULE:[2:$1@$0](jn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](nm@SUPPORT.COM)s/.*/yarn/ RULE:[2:$1@$0](nn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](rm@SUPPORT.COM)s/.*/yarn/ RULE:[2:$1@$0](yarn@SUPPORT.COM)s/.*/yarn/ . On Cluster2, append auth_to_local rules from Cluster1 Example on Cluster 2: RULE:[1:$1@$0](ambari-qa-support@SUPPORT.COM)s/.*/ambari-qa/ RULE:[1:$1@$0](hdfs-support@SUPPORT.COM)s/.*/hdfs/ RULE:[1:$1@$0](spark-support@SUPPORT.COM)s/.*/spark/ RULE:[1:$1@$0](.*@SUPPORT.COM)s/@.*// RULE:[2:$1@$0](dn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](hive@SUPPORT.COM)s/.*/hive/ RULE:[2:$1@$0](jhs@SUPPORT.COM)s/.*/mapred/ RULE:[2:$1@$0](jn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](nm@SUPPORT.COM)s/.*/yarn/ RULE:[2:$1@$0](nn@SUPPORT.COM)s/.*/hdfs/ RULE:[2:$1@$0](rm@SUPPORT.COM)s/.*/yarn/ RULE:[2:$1@$0](yarn@SUPPORT.COM)s/.*/yarn/ DEFAULT RULE:[1:$1@$0](ambari-qa-hadoop@HWX.COM)s/.*/ambari-qa/ RULE:[1:$1@$0](hdfs-hadoop@HWX.COM)s/.*/hdfs/ RULE:[1:$1@$0](spark-hadoop@HWX.COM)s/.*/spark/ RULE:[1:$1@$0](.*@HWX.COM)s/@.*// RULE:[2:$1@$0](dn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](hive@HWX.COM)s/.*/hive/ RULE:[2:$1@$0](jhs@HWX.COM)s/.*/mapred/ RULE:[2:$1@$0](jn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](nm@HWX.COM)s/.*/yarn/ RULE:[2:$1@$0](nn@HWX.COM)s/.*/hdfs/ RULE:[2:$1@$0](rm@HWX.COM)s/.*/yarn/ RULE:[2:$1@$0](yarn@HWX.COM)s/.*/yarn/ . Step 7: Login to Cluster 2, do a kinit by local user and try to access hdfs files of Cluster 1 Example: hdfs dfs -ls hdfs://hwx-2.hwx.com:8020/tmp Found 8 items drwx------   - ambari-qa hdfs          0 2016-07-29 23:24 hdfs://hwx-2.hwx.com:8020/tmp/ambari-qa drwxr-xr-x   - hdfs      hdfs          0 2016-07-29 22:02 hdfs://hwx-2.hwx.com:8020/tmp/entity-file-history drwx-wx-wx   - ambari-qa hdfs          0 2016-07-29 23:25 hdfs://hwx-2.hwx.com:8020/tmp/hive -rwxr-xr-x   3 hdfs      hdfs       1414 2016-07-29 23:50 hdfs://hwx-2.hwx.com:8020/tmp/id1aac2d44_date502916 -rwxr-xr-x   3 ambari-qa hdfs       1414 2016-07-29 23:26 hdfs://hwx-2.hwx.com:8020/tmp/idtest.ambari-qa.1469834803.19.in -rwxr-xr-x   3 ambari-qa hdfs        957 2016-07-29 23:26 hdfs://hwx-2.hwx.com:8020/tmp/idtest.ambari-qa.1469834803.19.pig drwxr-xr-x   - ambari-qa hdfs          0 2016-07-29 23:53 hdfs://hwx-2.hwx.com:8020/tmp/tezsmokeinput Note – hwx-2.hwx.com is the Active Namenode of Cluster 1. . You can try copying files from Cluster 2 to Cluster 1 using distcp Example: [kuldeepk@support-1 root]$ hadoop distcp hdfs://hwx-1.hwx.com:8020/tmp/test.txt /tmp/ 16/07/30 22:03:27 INFO tools.DistCp: Input Options: DistCpOptions{atomicCommit=false, syncFolder=false, deleteMissing=false, ignoreFailures=false, maxMaps=20, sslConfigurationFile='null', copyStrategy='uniformsize', sourceFileListing=null, sourcePaths=[hdfs://hwx-1.hwx.com:8020/tmp/test.txt], targetPath=/tmp, targetPathExists=true, preserveRawXattrs=false} 16/07/30 22:03:27 INFO impl.TimelineClientImpl: Timeline service address: http://support-3.support.com:8188/ws/v1/timeline/ 16/07/30 22:03:27 INFO client.RMProxy: Connecting to ResourceManager at support-3.support.com/172.26.68.50:8050 16/07/30 22:03:28 INFO hdfs.DFSClient: Created HDFS_DELEGATION_TOKEN token 20 for kuldeepk on 172.26.68.47:8020 16/07/30 22:03:28 INFO security.TokenCache: Got dt for hdfs://hwx-1.hwx.com:8020; Kind: HDFS_DELEGATION_TOKEN, Service: 172.26.68.47:8020, Ident: (HDFS_DELEGATION_TOKEN token 20 for kuldeepk) 16/07/30 22:03:29 INFO impl.TimelineClientImpl: Timeline service address: http://support-3.support.com:8188/ws/v1/timeline/ 16/07/30 22:03:29 INFO client.RMProxy: Connecting to ResourceManager at support-3.support.com/172.26.68.50:8050 16/07/30 22:03:29 INFO hdfs.DFSClient: Created HDFS_DELEGATION_TOKEN token 24 for kuldeepk on ha-hdfs:support 16/07/30 22:03:29 INFO security.TokenCache: Got dt for hdfs://support; Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:support, Ident: (HDFS_DELEGATION_TOKEN token 24 for kuldeepk) 16/07/30 22:03:29 INFO mapreduce.JobSubmitter: number of splits:1 16/07/30 22:03:29 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1469916118318_0003 16/07/30 22:03:29 INFO mapreduce.JobSubmitter: Kind: HDFS_DELEGATION_TOKEN, Service: 172.26.68.47:8020, Ident: (HDFS_DELEGATION_TOKEN token 20 for kuldeepk) 16/07/30 22:03:29 INFO mapreduce.JobSubmitter: Kind: HDFS_DELEGATION_TOKEN, Service: ha-hdfs:support, Ident: (HDFS_DELEGATION_TOKEN token 24 for kuldeepk) 16/07/30 22:03:30 INFO impl.YarnClientImpl: Submitted application application_1469916118318_0003 16/07/30 22:03:31 INFO mapreduce.Job: The url to track the job: http://support-3.support.com:8088/proxy/application_1469916118318_0003/ 16/07/30 22:03:31 INFO tools.DistCp: DistCp job-id: job_1469916118318_0003 16/07/30 22:03:31 INFO mapreduce.Job: Running job: job_1469916118318_0003 16/07/30 22:03:43 INFO mapreduce.Job: Job job_1469916118318_0003 running in uber mode : false 16/07/30 22:03:43 INFO mapreduce.Job:  map 0% reduce 0% 16/07/30 22:03:52 INFO mapreduce.Job:  map 100% reduce 0% 16/07/30 22:03:53 INFO mapreduce.Job: Job job_1469916118318_0003 completed successfully 16/07/30 22:03:53 INFO mapreduce.Job: Counters: 32   File System Counters     FILE: Number of bytes read=0     FILE: Number of bytes written=142927     FILE: Number of read operations=0     FILE: Number of large read operations=0     FILE: Number of write operations=0     HDFS: Number of bytes read=346     HDFS: Number of bytes written=45     HDFS: Number of read operations=12     HDFS: Number of large read operations=0     HDFS: Number of write operations=2   Job Counters     Launched map tasks=1     Other local map tasks=1     Total time spent by all maps in occupied slots (ms)=14324     Total time spent by all reduces in occupied slots (ms)=0     Total time spent by all map tasks (ms)=7162     Total vcore-seconds taken by all map tasks=7162     Total megabyte-seconds taken by all map tasks=7333888   Map-Reduce Framework     Map input records=1     Map output records=1     Input split bytes=118     Spilled Records=0     Failed Shuffles=0     Merged Map outputs=0     GC time elapsed (ms)=77     CPU time spent (ms)=1210     Physical memory (bytes) snapshot=169885696     Virtual memory (bytes) snapshot=2337554432     Total committed heap usage (bytes)=66584576   File Input Format Counters     Bytes Read=228   File Output Format Counters     Bytes Written=45   org.apache.hadoop.tools.mapred.CopyMapper$Counter     BYTESSKIPPED=0     SKIP=1 Note – hwx-1.hwx.com is the Active Namenode of Cluster 1. . Please comment if you have any feedback/questions/suggestions. Happy Hadooping!! 🙂 References: http://crazyadmins.com https://community.hortonworks.com/articles/18686/kerberos-cross-realm-trust-for-distcp.html ... View more