How to send ICMP packet in JAVA

[Jingui Yang]

Dear all:
How to send ICMP packet in JAVA,and how to program with
"native"?(such as C,C++)

import java.net.*;

public class ICMP
{
static
{
System.loadLibrary( "icmplib" );
}

private int m_socket;

public ICMP( ) throws SocketException
{
initialize();
m_socket = createSocket();
}

public boolean sendPing ( InetAddress host, int timeout )
{
try
{
sendICMP( m_socket,
host.getHostAddress(),
System.currentTimeMillis() );

return (recvICMP( m_socket, timeout ) != 0 );
} catch ( Exception e )
{
return false;
}
}

public void finalize( )throws Throwable
{
closeSocket( m_socket );
super.finalize();
}

private static native long initialize( ) throws SocketException;

private static native int createSocket( );

private static native long sendICMP( int socket,
String host,
long ID);

private static native long recvICMP ( int socket, long timeout );

private static native boolean closeSocket( int socket );
}

import java.net.*;
public class Ping
{

public static void main (String[] args)
{
if ( args.length > 0 )
{
try
{
ICMP ping = new ICMP();
for ( int argCounter = 0; argCounter < args.length;
argCounter++ )
{
try
{
for ( int i = 0; i < 4; i++ )
{
InetAddress addr = InetAddress.getByName(
args[argCounter] );
System.out.print ( "Sending " + addr +
"... " );
if ( ping.sendPing ( addr, 5000 ) == true
)
{
System.out.println ( "Reply" );
} else
{
System.out.println ( "Time out" );
}
} // for i
} catch ( UnknownHostException e )
{
System.out.println ( "Unknown host: " +
args[argCounter] );
}
} // for argCounter
} catch ( SocketException e )
{
System.out.println ( e.getMessage() );
} // catch
} else
{
System.out.println ( "ping <hostname>" );
}
}

}

When I do this: java Ping 202.114.39.1
there are errors:
Exception in thread "main" java.lang.UnsatisfiedLinkError:no icmplib
in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at ICMP.<clinit>(ICMP.java:7)
at Ping.main(Ping.java:13)
In the same directory,there are some other files:
icmplib.c,icmplib.def,icmplib.dsp,icmplib.dsw,native.h

[Gordon Beaton]

On 4 Apr 2002 02:02:55 -0800, Jingui Yang wrote:
> How to send ICMP packet in JAVA

Java has no support for sending or receiving ICMP packets.

> ,and how to program with "native"?(such as C,C++)

Have a look at the JNI spec and tutorial:

http://java.sun.com/j2se/1.4/docs/guide/jni/index.html

If it's this error you are asking about:

> Exception in thread "main" java.lang.UnsatisfiedLinkError:no icmplib
> in java.library.path

then it means that the native library ("libicmplib.so" or
"icmplib.dll", depending on your OS) could not be found in the
LD_LIBRARY_PATH or PATH (again, depending on your OS).

/gordon

--
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