How do I restrict Apache Tomcat to listen only IPv4 address?

Solution Verified - Updated

Environment

  • Red Hat Enterprise Linux
  • Apache Tomcat

Issue

  • How do I restrict Tomcat to listen only on ipv4 address ?

  • By default Tomcat listens only on IPv6 addresses. Following netstat output shows Tomcat is listening only on IPv6 address.

      tcp        0      0 :::8009   :::*   LISTEN      91         8474899    29185/java          off (0.00/0/0)
  tcp        0      0 :::8080   :::*   LISTEN      91         8474862    29185/java          off (0.00/0/0)

Resolution

The -Djava.net.preferIPv4Stack=true JVM startup option can be used to force IPv4 stack to be used by the JVM.

This can be done by adding -Djava.net.preferIPv4Stack=true as a parameter for JAVA_OPTS for Tomcat. Please see this solution on how to configure Tomcat JVM startup options: How to set the JVM options for Tomcat on Linux

Make sure to restart the Apache Tomcat service after adding the JVM option.

Root Cause

As a default, if IPV6 support enabled in kernel,the Java Runtime will use IPV6 sockets to communicate.

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