JSP獲得客服端MAC地址

package com.sun.servlet;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
 * 主機A向主機B發送“UDP－NetBIOS－NS”詢問包，即向主機B的137端口，發Query包來詢問主機B的NetBIOS Names信息。
 * 其次，主機B接收到“UDP－NetBIOS－NS”詢問包，假設主機B正確安裝了NetBIOS服務........... 而且137端口開放，則主機B會向主機A發送一個“UDP－NetBIOS－NS”應答包，即發Answer包給主機A。
 * 并利用UDP(NetBIOS Name Service)來快速獲取遠程主機MAC地址的方法
 * 
 * @author WINDY
 */
public class UdpGetClientMacAddr {
	private String sRemoteAddr;
	private int iRemotePort=137;
	private byte[] buffer = new byte[1024];
	private DatagramSocket ds=null;

	public UdpGetClientMacAddr(String strAddr) throws Exception{
		sRemoteAddr = strAddr;
		ds = new DatagramSocket();
	}

	protected final DatagramPacket send(final byte[] bytes) throws IOException {
		DatagramPacket dp = new DatagramPacket(bytes,bytes.length,InetAddress.getByName(sRemoteAddr),iRemotePort);
		ds.send(dp);
		return dp;
	}

	protected final DatagramPacket receive() throws Exception {
		DatagramPacket dp = new DatagramPacket(buffer,buffer.length);
		ds.receive(dp);
		return dp;
	}
	protected byte[] GetQueryCmd() throws Exception {
		byte[] t_ns = new byte[50];
		t_ns[0] = 0x00;
		t_ns[1] = 0x00;
		t_ns[2] = 0x00;
		t_ns[3] = 0x10;
		t_ns[4] = 0x00;
		t_ns[5] = 0x01;
		t_ns[6] = 0x00;
		t_ns[7] = 0x00;
		t_ns[8] = 0x00;
		t_ns[9] = 0x00;
		t_ns[10] = 0x00;
		t_ns[11] = 0x00;
		t_ns[12] = 0x20;
		t_ns[13] = 0x43;
		t_ns[14] = 0x4B;

		for(int i = 15; i < 45; i++){
			t_ns[i] = 0x41;
		}
		t_ns[45] = 0x00;
		t_ns[46] = 0x00;
		t_ns[47] = 0x21;
		t_ns[48] = 0x00;
		t_ns[49] = 0x01;
		return t_ns;
	}
	protected final String GetMacAddr(byte[] brevdata) throws Exception {
		// 獲取計算機名
		int i = brevdata[56] * 18 + 56;
		String sAddr="";
		StringBuffer sb = new StringBuffer(17);
		// 先從第56字節位置，讀出Number Of Names（NetBIOS名字的個數，其中每個NetBIOS Names Info部分占18個字節）
		// 然后可計算出“Unit ID”字段的位置＝56＋Number Of Names×18，最后從該位置起連續讀取6個字節，就是目的主機的MAC地址。
		for(int j = 1; j < 7;j++)
		{
			sAddr = Integer.toHexString(0xFF & brevdata[i+j]);
			if(sAddr.length() < 2)
			{
				sb.append(0);
			}
			sb.append(sAddr.toUpperCase());
			if(j < 6) sb.append(':');
		}
		return sb.toString();
	}

	public final void close() {
		try
		{
			ds.close();
		}
		catch (Exception ex){
			ex.printStackTrace();
		}
	}

	public final String GetRemoteMacAddr() throws Exception {
		byte[] bqcmd = GetQueryCmd();
		send(bqcmd);
		DatagramPacket dp = receive();
		String smac = GetMacAddr(dp.getData());
		close();

		return smac;
	}
}

<span style="color:#000000;"><%
				String smac = "";
				String sip = request.getHeader("x-forwarded-for");
				if (sip == null || sip.length() == 0
						|| "unknown".equalsIgnoreCase(sip)) {
					sip = request.getHeader("Proxy-Client-IP");
				}
				if (sip == null || sip.length() == 0
						|| "unknown".equalsIgnoreCase(sip)) {
					sip = request.getHeader("WL-Proxy-Client-IP");
				}
				if (sip == null || sip.length() == 0
						|| "unknown".equalsIgnoreCase(sip)) {
					sip = request.getRemoteAddr();
				}
				UdpGetClientMacAddr umac = new UdpGetClientMacAddr(sip);
				smac = umac.GetRemoteMacAddr();
				session.setAttribute("smac", smac);
			%></span>