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  1. Hadoop Common
  2. HADOOP-15250

Split-DNS MultiHomed Server Network Cluster Network IPC Client Bind Addr Wrong



    • Improvement
    • Status: Resolved
    • Critical
    • Resolution: Fixed
    • 2.7.3, 2.9.0, 3.0.0
    • 3.2.0, 3.1.1
    • ipc, net
    • None
    • Multihome cluster with split DNS and rDNS lookup of localhost returning non-routable IPAddr


      We run our Hadoop clusters with two networks attached to each node. These network are as follows a server network that is firewalled with firewalld allowing inbound traffic: only SSH and things like Knox and Hiveserver2 and the HTTP YARN RM/ATS and MR History Server. The second network is the cluster network on the second network interface this uses Jumbo frames and is open no restrictions and allows all cluster traffic to flow between nodes. 


      To resolve DNS within the Hadoop Cluster we use DNS Views via BIND so if the traffic is originating from nodes with cluster networks we return the internal DNS record for the nodes. This all works fine with all the multi-homing features added to Hadoop 2.x

       Some logic around views:

      a. The internal view is used by cluster machines when performing lookups. So hosts on the cluster network should get answers from the internal view in DNS
      b. The external view is used by non-local-cluster machines when performing lookups. So hosts not on the cluster network should get answers from the external view in DNS


      So this brings me to our problem. We created some firewall rules to allow inbound traffic from each clusters server network to allow distcp to occur. But we noticed a problem almost immediately that when YARN attempted to talk to the Remote Cluster it was binding outgoing traffic to the cluster network interface which IS NOT routable. So after researching the code we noticed the following in NetUtils.java and Client.java 

      Basically in Client.java it looks as if it takes whatever the hostname is and attempts to bind to whatever the hostname is resolved to. This is not valid in a multi-homed network with one routable interface and one non routable interface. After reading through the java.net.Socket documentation it is valid to perform socket.bind(null) which will allow the OS routing table and DNS to send the traffic to the correct interface. I will also attach the nework traces and a test patch for 2.7.x and 3.x code base. I have this test fix below in my Hadoop Test Cluster.



      • Bind the socket to the host specified in the principal name of the
      • client, to ensure Server matching address of the client connection
      • to host name in principal passed.
        InetSocketAddress bindAddr = null;
        if (ticket != null && ticket.hasKerberosCredentials()) {
        KerberosInfo krbInfo =
        if (krbInfo != null) {
        String principal = ticket.getUserName();
        String host = SecurityUtil.getHostFromPrincipal(principal);
        // If host name is a valid local address then bind socket to it
        InetAddress localAddr = NetUtils.getLocalInetAddress(host);
       **  if (localAddr != null) {
        if (LOG.isDebugEnabled()) {| | |LOG.debug("Binding " + principal + " to " + localAddr);| | |}
        bindAddr = new InetSocketAddress(localAddr, 0);


      So in my Hadoop 2.7.x Cluster I made the following changes and traffic flows correctly out the correct interfaces:


      diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java

      index e1be271..c5b4a42 100644

      — a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java

      +++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java

      @@ -305,6 +305,9 @@

         public static final String  IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_KEY = "ipc.client.fallback-to-simple-auth-allowed";

         public static final boolean IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_DEFAULT = false;


      +  public static final String  IPC_CLIENT_NO_BIND_LOCAL_ADDR_KEY = "ipc.client.nobind.local.addr";

      +  public static final boolean IPC_CLIENT_NO_BIND_LOCAL_ADDR_DEFAULT = false;


         public static final String IPC_CLIENT_CONNECT_MAX_RETRIES_ON_SASL_KEY =


         public static final int    IPC_CLIENT_CONNECT_MAX_RETRIES_ON_SASL_DEFAULT = 5;

      diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

      index a6f4eb6..7bfddb7 100644

      — a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

      +++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

      @@ -129,7 +129,9 @@ public static void setCallIdAndRetryCount(int cid, int rc) {


         private final int connectionTimeout;



         private final boolean fallbackAllowed;

      +  private final boolean noBindLocalAddr;

         private final byte[] clientId;


         final static int CONNECTION_CONTEXT_CALL_ID = -3;

      @@ -642,7 +644,11 @@ private synchronized void setupConnection() throws IOException {

                     InetAddress localAddr = NetUtils.getLocalInetAddress(host);

                     if (localAddr != null) {


      -                this.socket.bind(new InetSocketAddress(localAddr, 0));

      +                if (noBindLocalAddr)

      { +                  this.socket.bind(null); + }


      { +                  this.socket.bind(new InetSocketAddress(localAddr, 0)); +                }





        1. HADOOP-15250-branch-3.1.patch
          6 kB
          Ajay Kumar
        2. HADOOP-15250.02.patch
          6 kB
          Ajay Kumar
        3. HADOOP-15250.01.patch
          6 kB
          Ajay Kumar
        4. HADOOP-15250.00.patch
          6 kB
          Ajay Kumar
        5. HADOOP-15250.patch
          3 kB
          Greg Senia



            ajayydv Ajay Kumar
            gss2002 Greg Senia
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