Network Interface in Java

 Network Interface in Java

A network interface is the point of interconnection between a computer and a private or public network. A network interface is generally a network interface card (NIC). Java 1.4 introduced NetworkInterface Class to get the details of a local network interface, MAC address of the Interface, MTU (maximum transmission unit) of the Interface, list of IP address attached to the interface whether the interface up and/or down and whether it supports multicasting etc.

NetworkInterface is useful for a multihomed system, which is a system with multiple NICs. Using NetworkInterface, you can specify which NIC to use for a particular network activity. The NetworkInterface class is given by Java in a package named java.net and the NetworkInterface class represents both types of interfaces.

Example

The loop back interface (127.0.0.1 for IPv4 and 1 for IPv6) is not a physical device but a piece of software simulating a network interface. The loop back interface is commonly used in test enviorments.

code

import java.net.*;

import java.io.*;

import java.net.*;

import java.util.*;

public class DemoNetworkInterface

{

private static final String NL = System.getProperty("line.separator");

private static final String NL_TAB = NL + "  ";

private static final String IPV4 = "IPv4";

private static final String IPV6 = "IPv6";

 

private static class MyInterface

{

public String displayName;

public String name;

public int mtu;

public boolean isUp;

public boolean isLoopback;

public boolean isPointToPoint; // e.g. a PPP modem interface

public boolean isVirtual;      // a sub-interface

public boolean supportsMulticast;

public byte[] macAddress;

public List<MyIpAddress> ipAddresses;

public List<MyInterface> subInterfaces;

 

public String toString()

{

StringBuilder sb = new StringBuilder(NL);

sb.append("*** Interface [" + name + "] ***").append(NL);

sb.append(NL).append("Name  : " + displayName);

sb.append(NL).append("MTU           : " + mtu);

sb.append(NL).append("Loop back     : " + isLoopback);

sb.append(NL).append("Point to Point: " + isPointToPoint);

sb.append(NL).append(" InterFace is up    : " + isUp);

sb.append(NL).append("virtual       : " + isVirtual);

sb.append(NL).append("multicast     : " + supportsMulticast);

sb.append(NL).append("MAC address  : ");

if (macAddress != null)

{

for (byte b : macAddress)

{

sb.append(String.format("%1$02X ", b));

}

}

else

{

sb.append("n/a");

}

for (MyIpAddress ipAddr: ipAddresses)

{

sb.append(ipAddr);

}

for (MyInterface subInfo: subInterfaces)

{

sb.append(subInfo);

}

return sb.toString();

}

}

private static class MyIpAddress

{

public String ipAddress;

public String ipVersion = "unknown";

public String hostName;

public String canonicalHostName;

public boolean isLoopback;

public boolean isSiteLocal; // private IP address

public boolean isAnyLocal;  // wildcard address

public boolean isLinkLocal;

public boolean isMulticast;

public boolean isReachable;

public String toString()

{

StringBuilder sb = new StringBuilder();

sb.append(NL).append("INET address ("+ ipVersion + "): " + ipAddress);

sb.append(NL_TAB).append("host name           : " + hostName);

sb.append(NL_TAB).append("canonical host name : " + canonicalHostName);

sb.append(NL_TAB).append("loopback        : " + isLoopback);

sb.append(NL_TAB).append("site local        : " + isSiteLocal);

sb.append(NL_TAB).append("any local        : " + isAnyLocal);

sb.append(NL_TAB).append("link local         : " + isLinkLocal);

sb.append(NL_TAB).append("multicast        : " + isMulticast);

sb.append(NL_TAB).append("reachable       : " + isReachable);

return sb.toString();

}

}

private static MyInterface getMyInterface(NetworkInterface nif) throws IOException

{

// get interface information

MyInterface info = new MyInterface();

info.displayName = nif.getDisplayName();

info.name = nif.getName();

info.mtu = nif.getMTU();

info.isUp = nif.isUp();

info.isLoopback = nif.isLoopback();

info.isPointToPoint = nif.isPointToPoint();

info.isVirtual = nif.isVirtual();

info.supportsMulticast = nif.supportsMulticast();

info.macAddress = nif.getHardwareAddress();

info.ipAddresses = new ArrayList<MyIpAddress>();

info.subInterfaces = new ArrayList<MyInterface>();

// get IP address information

Enumeration<InetAddress> inetAddresses = nif.getInetAddresses();

while (inetAddresses.hasMoreElements())

{

InetAddress inetAddr = inetAddresses.nextElement();

MyIpAddress ipInfo = new MyIpAddress();

if (inetAddr instanceof Inet4Address)

{

ipInfo.ipVersion = IPV4;

}

else if (inetAddr instanceof Inet6Address)

{

ipInfo.ipVersion = IPV6;

}

ipInfo.ipAddress = inetAddr.getHostAddress();

ipInfo.hostName = inetAddr.getHostName();

ipInfo.canonicalHostName = inetAddr.getCanonicalHostName();

ipInfo.isAnyLocal = inetAddr.isAnyLocalAddress();

ipInfo.isLinkLocal = inetAddr.isLinkLocalAddress();

ipInfo.isSiteLocal = inetAddr.isSiteLocalAddress();

ipInfo.isLoopback = inetAddr.isLoopbackAddress();

ipInfo.isMulticast = inetAddr.isMulticastAddress();

ipInfo.isReachable = inetAddr.isReachable(5000);

info.ipAddresses.add(ipInfo);

}

// get virtual interface information

Enumeration<NetworkInterface> subIfs = nif.getSubInterfaces();

while (subIfs.hasMoreElements())

{

NetworkInterface subIf = subIfs.nextElement();

MyInterface subInfo = getMyInterface(subIf);

info.subInterfaces.add(subInfo);

}

return info;

}

public static void main(String[] args) throws IOException

{

Enumeration<NetworkInterface> interfaces =

NetworkInterface.getNetworkInterfaces();

 while (interfaces.hasMoreElements())

{

NetworkInterface nif = interfaces.nextElement();

System.out.println(getMyInterface(nif));

}

}

}

Output

The following output provides many information from the NIC (Network Interface Card) of your system.



Resource

Java naming and directory interface(JNDI)

Interfaces of collection in JAVA

Introduction to Jdbc

Use of ByteStreams and CharacterStreams in JAVA

Learning JDBC (Java Database Connectivity)