截取TCP/IP报文,,怎么去做啊

[bluegoats]

对网络的传输有了一点点了解,,但还是不知道怎么去截取,
我想肯定不是在网卡上截取吧,,,

[David_lee]

肯定是在网卡上截取，把网卡置混合模式……，用Vxd读网卡?反正复杂。
这种程序当然犯不着自己去编了，也编不了，：） 用netxray就行了
再找45 00头，去掉IP，如果协议是6(TCP)再去掉TCP不就行了。
至于格式，不用多言吧，如果想要去格式的程序，E_mail [e-mail]，我今天刚做完。有缘分 ：）
不过不要急，因为我下次上网什么时候就不定了。

[stn]

用win2k和原始套接字也可以的

[David_lee]

同意，win2k的netmonitor也有此功能。
但是原始套接字如何实现还请赐教
有代码或者伪代码也行。
原始套接字不会过滤掉TCP/IP吗？

[bluetooth_2001]

faint!

[shen630]

研究研究

[7]

好长.....

[BallyTan]

拿回去看了

[newworld_ni]

我这边有源码，希望能给分。



// Module: rcvall.c
//
// Description:
// This sample shows how to use the ioctls SIO_RCVALL,
// SIO_RCVALL_MCAST, and SIO_RCVALL_IGMPMCAST. This sample
// captures all packets of the given type and also is able
// to set filters on source and destination IP addresses
// and ports. This sample is Windows 2000 only.
//
// Compile:
// cl rcvall.c parser.c ws2_32.lib
//
// Command Line Arguments/Parameters
// rcvall.exe -t:[ip|igmp|multicast] -i:int -sa:IP -sp:port
// -da:IP -dp:port
// -t:string Filter traffic type
// ip Capture all IP packets
// igmp Capture all IGMP packets only
// multicast Capture all multicast IP packets
// -i:int Capture on this interface
// This is a zero based index of the
// local interfaces
// -sa:IP Filter on source address
// -sp:Port Filter on source port
// -da:IP Filter on dest address
// -dp:Port Filter on dest port
//
//
#include "parser.h"

#include <mstcpip.h>
#include <ws2tcpip.h>

#include <stdio.h>
#include <stdlib.h>

DWORD dwIoControlCode=SIO_RCVALL,
dwProtocol=IPPROTO_IP,
dwInterface=0;

//
// Filters
//
unsigned int uiSourceAddr=0,
uiDestAddr=0;
unsigned short usSourcePort = 0,
usDestPort = 0;
BOOL bFilter=FALSE;

void PrintInterfaceList();
int GetInterface(SOCKET s, SOCKADDR_IN *ifx, int num);

//
// Function: usage
//
// Description:
// Prints usage information.
//
void usage(char *progname)
{
printf("usage: %s -t:traffic-type [interface-num]\n\n", progname);
printf(" -t:string Filter traffic type\n");
printf(" Available traffic types:\n");
printf(" ip Capture all IP packets\n");
printf(" igmp Capture all IGMP packets only\n");
printf(" multicast Capture all multicast IP packets\n");
printf(" -i:int Capture on this interface\n");
printf(" Available interfaces:\n");
PrintInterfaceList();
printf(" -sa:IP Filter on source address\n");
printf(" -sp:Port Filter on source port\n");
printf(" -da:IP Filter on dest address\n");
printf(" -dp:Port Filter on dest port\n");

WSACleanup();
ExitProcess(-1);
}

//
// Function: ValidateArgs
//
// Description:
// This function parses the command line arguments and
// sets global variables to indicate how the app should act.
//
void ValidateArgs(int argc, char **argv)
{
int i;
char *ptr;

for(i=1; i < argc ;i++)
{
if (strlen(argv[i]) < 2)
continue;
if ((argv[i][0] == '-') || (argv[i][0] == '/'))
{
switch (tolower(argv[i][1]))
{
case 't': // traffic type
ptr = &argv[i][3];
while (*ptr)
*ptr++ = tolower(*ptr);

if (!strcmp(&argv[i][3], "ip"))
{
dwIoControlCode = SIO_RCVALL;
dwProtocol = IPPROTO_IP;
}
else if (!strcmp(&argv[i][3], "igmp"))
{
dwIoControlCode = SIO_RCVALL_IGMPMCAST;
dwProtocol = IPPROTO_IGMP;
}
else if (!strcmp(&argv[i][3], "multicast"))
{
dwIoControlCode = SIO_RCVALL_MCAST;
dwProtocol = IPPROTO_IGMP;
}
else
usage(argv[0]);
break;
case 'i': // interface number
dwInterface = atoi(&argv[i][3]);
break;
case 's': // Filter on source ip or port
if (tolower(argv[i][2]) == 'a')
uiSourceAddr = ntohl(inet_addr(&argv[i][4]));
else if (tolower(argv[i][2]) == 'p')
usSourcePort = (unsigned short)atoi(&argv[i][4]);
else
usage(argv[0]);
bFilter = TRUE;
break;
case 'd': // Filter on dest ip or port
if (tolower(argv[i][2]) == 'a')
uiDestAddr = ntohl(inet_addr(&argv[i][4]));
else if (tolower(argv[i][2]) == 'p')
usDestPort = (unsigned short)atoi(&argv[i][4]);
else
usage(argv[0]);
bFilter = TRUE;
break;
default:
usage(argv[0]);
}
}
}
return;
}

//
// Function: PrintInterfaceList
//
// Description:
// This function prints all local IP interfaces.
//
void PrintInterfaceList()
{
SOCKET_ADDRESS_LIST *slist=NULL;
SOCKET s;
char buf[2048];
DWORD dwBytesRet;
int ret,
i;

s = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
if (s == SOCKET_ERROR)
{
printf("socket() failed: %d\n", WSAGetLastError());
return;
}
ret = WSAIoctl(s, SIO_ADDRESS_LIST_QUERY, NULL, 0, buf, 2048,
&dwBytesRet, NULL, NULL);
if (ret == SOCKET_ERROR)
{
printf("WSAIoctl(SIO_ADDRESS_LIST_QUERY) failed: %d\n",
WSAGetLastError());
return;
}
slist = (SOCKET_ADDRESS_LIST *)buf;
for(i=0; i < slist->iAddressCount ;i++)
{
printf(" %d [%s]\n", i,
inet_ntoa(((SOCKADDR_IN *)slist->Address[i].lpSockaddr)->sin_addr));
}
closesocket(s);
return;
}

//
// Function: GetInterface
//
// Description:
// This function retrieves a zero based index and returns
// the IP interface corresponding to that.
//
int GetInterface(SOCKET s, SOCKADDR_IN *ifx, int num)
{
SOCKET_ADDRESS_LIST *slist=NULL;
char buf[2048];
DWORD dwBytesRet;
int ret;

ret = WSAIoctl(s, SIO_ADDRESS_LIST_QUERY, NULL, 0, buf, 2048,
&dwBytesRet, NULL, NULL);
if (ret == SOCKET_ERROR)
{
printf("WSAIoctl(SIO_ADDRESS_LIST_QUERY) failed: %d\n",
WSAGetLastError());
return -1;
}
slist = (SOCKET_ADDRESS_LIST *)buf;

if (num >= slist->iAddressCount)
return -1;

ifx->sin_addr.s_addr = ((SOCKADDR_IN *)slist->Address[num].lpSockaddr)->sin_addr.s_addr;

return 0;
}

//
// Function: main
//
// Description:
// This function loads Winsock, parses the command line, and
// begins receiving packets. Once a packet is received they
// are decoded. Because we are receiving IP datagrams, the
// receive call will return whole datagrams.
//
int main(int argc, char **argv)
{
SOCKET s;
WSADATA wsd;
SOCKADDR_IN if0;
int ret,
count;
unsigned int optval;
DWORD dwBytesRet,
dwFlags,
nproc;
char rcvbuf[MAX_IP_SIZE];
WSABUF wbuf;

// Load Winsock
//
if (WSAStartup(MAKEWORD(2,2), &wsd) != 0)
{
printf("WSAStartup() failed: %d\n", GetLastError());
return -1;
}
// Parse the command line
//
ValidateArgs(argc, argv);
if (bFilter)
{
printf("Source Port: %d\n", usSourcePort);
printf("Dest Port: %d\n", usDestPort);
}
// Create a raw socket for receiving IP datagrams
//
s = WSASocket(AF_INET, SOCK_RAW, dwProtocol, NULL, 0, WSA_FLAG_OVERLAPPED);
if (s == INVALID_SOCKET)
{
printf("WSASocket() failed: %d\n", WSAGetLastError());
return -1;
}
// Get an interface to read IP packets on
//
if (GetInterface(s, &if0, dwInterface) != 0)
{
printf("Unable to obtain an interface\n");
return -1;
}
printf("Binding to IF: %s\n", inet_ntoa(if0.sin_addr));
//
// This socket must be bound before calling the ioctl
//
if0.sin_family = AF_INET;
if0.sin_port = htons(0);

if (bind(s, (SOCKADDR *)&if0, sizeof(if0)) == SOCKET_ERROR)
{
printf("bind() failed: %d\n", WSAGetLastError());
return -1;
}
//
// Set the SIO_RCVALLxxx ioctl
//
optval = 1;
if (WSAIoctl(s, dwIoControlCode, &optval, sizeof(optval),
NULL, 0, &dwBytesRet, NULL, NULL) == SOCKET_ERROR)
{
printf("WSAIotcl(%d) failed; %d\n", dwIoControlCode,
WSAGetLastError());
return -1;
}
// Start receiving IP datagrams until interrupted
//
count = 0;
while (1)
{
wbuf.len = MAX_IP_SIZE;
wbuf.buf = rcvbuf;
dwFlags = 0;

ret = WSARecv(s, &wbuf, 1, &dwBytesRet, &dwFlags, NULL, NULL);
if (ret == SOCKET_ERROR)
{
printf("WSARecv() failed: %d\n", WSAGetLastError());
return -1;
}
// Decode the IP header
//
if (!(nproc = DecodeIPHeader(&wbuf, uiSourceAddr, usSourcePort,
uiDestAddr, usDestPort)))
{
printf("Error decoding IP header!\n");
break;
}
}
// Cleanup
//
closesocket(s);
WSACleanup();
return 0;
}
//parser.h

#ifndef _RCVALL_H_
#define _RCVALL_H_

#include <winsock2.h>
#include <windows.h>

#define MAX_IP_SIZE 65535
#define MIN_IP_HDR_SIZE 20

#define HI_WORD(byte) (((byte) >> 4) & 0x0F)
#define LO_WORD(byte) ((byte) & 0x0F)

extern char *szProto[];



void PrintRawBytes (BYTE *ptr, DWORD len);
int DecodeIGMPHeader(WSABUF *wsabuf, DWORD iphdrlen);
int DecodeUDPHeader (WSABUF *wsabuf, DWORD iphdrlen);
int DecodeTCPHeader (WSABUF *wsabuf, DWORD iphdrlenz);
int DecodeIPHeader (WSABUF *wasbuf, unsigned int srcaddr,
unsigned short srcport, unsigned int destaddr, unsigned short destport);

#endif


// Module: parser.c
//
// Description:
// This file is the companion to rcvall.c and contains
// the parser routines for printing out IP, UDP, TCP,
// ICMP, and IGMP packets.
//
// Compile:
// cl /c parser.c
//
// Command Line Arguments/Parameters
// None
//
#include <stdio.h>
#include <stdlib.h>

#include "parser.h"

extern BOOL bFilter;
//
// A list of protocol types in the IP protocol header
//
char *szProto[] = {"Reserved", // 0
"ICMP", // 1
"IGMP", // 2
"GGP", // 3
"IP", // 4
"ST", // 5
"TCP", // 6
"UCL", // 7
"EGP", // 8
"IGP", // 9
"BBN-RCC-MON", // 10
"NVP-II", // 11
"PUP", // 12
"ARGUS", // 13
"EMCON", // 14
"XNET", // 15
"CHAOS", // 16
"UDP", // 17
"MUX", // 18
"DCN-MEAS", // 19
"HMP", // 20
"PRM", // 21
"XNS-IDP", // 22
"TRUNK-1", // 23
"TRUNK-2", // 24
"LEAF-1", // 25
"LEAF-2", // 26
"RDP", // 27
"IRTP", // 28
"ISO-TP4", // 29
"NETBLT", // 30
"MFE-NSP", // 31
"MERIT-INP", // 32
"SEP", // 33
"3PC", // 34
"IDPR", // 35
"XTP", // 36
"DDP", // 37
"IDPR-CMTP", // 38
"TP++", // 39
"IL", // 40
"SIP", // 41
"SDRP", // 42
"SIP-SR", // 43
"SIP-FRAG", // 44
"IDRP", // 45
"RSVP", // 46
"GRE", // 47
"MHRP", // 48
"BNA", // 49
"SIPP-ESP", // 50
"SIPP-AH", // 51
"I-NLSP", // 52
"SWIPE", // 53
"NHRP", // 54
"unassigned", // 55
"unassigned", // 56
"unassigned", // 57
"unassigned", // 58
"unassigned", // 59
"unassigned", // 60
"any host internal protocol", // 61
"CFTP", // 62
"any local network", // 63
"SAT-EXPAK", // 64
"KRYPTOLAN", // 65
"RVD", // 66
"IPPC", // 67
"any distributed file system", // 68
"SAT-MON", // 69
"VISA", // 70
"IPCV", // 71
"CPNX", // 72
"CPHB", // 73
"WSN", // 74
"PVP", // 75
"BR-SAT-MON", // 76
"SUN-ND", // 77
"WB-MON", // 78
"WB-EXPAK", // 79
"ISO-IP", // 80
"VMTP", // 81
"SECURE-VMTP",// 82
"VINES", // 83
"TTP", // 84
"NSFNET-IGP", // 85
"DGP", // 86
"TCF", // 87
"IGRP", // 88
"OSPFIGP", // 89
"Sprite-RPC", // 90
"LARP", // 91
"MTP", // 92
"AX.25", // 93
"IPIP", // 94
"MICP", // 95
"SCC-SP", // 96
"ETHERIP", // 97
"ENCAP", // 98
"any private encryption scheme", // 98
"GMTP" // 99
};
//
// The types of IGMP messages
//
char *szIgmpType[] = {"",
"Host Membership Query",
"HOst Membership Report",
"",
"",
"",
"Version 2 Membership Report",
"Leave Group"
};

//
// Function: PrintRawBytes
//
// Description:
// This function simply prints out a series of bytes
// as hexadecimal digits.
//
void PrintRawBytes(BYTE *ptr, DWORD len)
{
int i;

while (len > 0)
{
for(i=0; i < 20 ;i++)
{
printf("%x%x ", HI_WORD(*ptr), LO_WORD(*ptr));
len--;
ptr++;
if (len == 0)
break;
}
printf("\n");
}
}

//
// Function: DecodeIGMPHeader
//
// Description:
// This function takes a pointer to a buffer containing
// an IGMP packet and prints it out in a readable form.
//
int DecodeIGMPHeader(WSABUF *wsabuf, DWORD iphdrlen)
{
BYTE *hdr = (BYTE *)(wsabuf->buf + iphdrlen);
unsigned short chksum,
version,
type,
maxresptime;
SOCKADDR_IN addr;

version = HI_WORD(*hdr);
type = LO_WORD(*hdr);
hdr++;

maxresptime = *hdr;
hdr++;

memcpy(&chksum, hdr, 2);
chksum = ntohs(chksum);
hdr += 2;

memcpy(&(addr.sin_addr.s_addr), hdr, 4);

printf(" IGMP HEADER:\n");
if ((type == 1) || (type == 2))
version = 1;
else
version = 2;
printf(" IGMP Version = %d\n", version);
printf(" IGMP Type = %s\n", szIgmpType[type]);
if (version == 2)
printf(" Max Resp Time = %d\n", maxresptime);
printf(" IGMP Grp Addr = %s\n", inet_ntoa(addr.sin_addr));
//ExitProcess(0);

return 0;
}

//
// Function: DecodeUDPHeader
//
// Description:
// This function takes a buffer which points to a UDP
// header and prints it out in a readable form.
//
int DecodeUDPHeader(WSABUF *wsabuf, DWORD iphdrlen)
{
BYTE *hdr = (BYTE *)(wsabuf->buf + iphdrlen);
unsigned short shortval,
udp_src_port,
udp_dest_port,
udp_len,
udp_chksum;

memcpy(&shortval, hdr, 2);
udp_src_port = ntohs(shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
udp_dest_port = ntohs(shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
udp_len = ntohs(shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
udp_chksum = ntohs(shortval);

printf(" UDP HEADER\n");
printf(" Source Port: %-05d | Dest Port: %-05d\n",
udp_src_port, udp_dest_port);
printf(" UDP Len: %-05d | ChkSum: 0x%08x\n",
udp_len, udp_chksum);
return 0;
}

//
// Function: DecodeTCPHeader
//
// Description:
// This function takes a buffer pointing to a TCP header
// and prints it out in a readable form.
//
int DecodeTCPHeader(WSABUF *wsabuf, DWORD iphdrlen)
{
BYTE *hdr = (BYTE *)(wsabuf->buf + iphdrlen);
unsigned short shortval;
unsigned int longval;

printf(" TCP HEADER\n");
memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval);
printf(" Src Port : %d\n", shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval);
printf(" Dest Port : %d\n", shortval);
hdr += 2;

memcpy(&longval, hdr, 4);
longval = ntohl(longval);
printf(" Seq Num : %d\n", longval);
hdr += 4;

memcpy(&longval, hdr, 4);
longval = ntohl(longval);
printf(" ACK Num : %d\n", longval);
hdr += 4;

printf(" Header Len : %d (bytes %d)\n", HI_WORD(*hdr),
(HI_WORD(*hdr) * 4));

memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval) & 0x3F;
printf(" Flags : ");
if (shortval & 0x20)
printf("URG ");
if (shortval & 0x10)
printf("ACK ");
if (shortval & 0x08)
printf("PSH ");
if (shortval & 0x04)
printf("RST ");
if (shortval & 0x02)
printf("SYN ");
if (shortval & 0x01)
printf("FIN ");
printf("\n");
hdr += 2;

memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval);
printf(" Window size: %d\n", shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval);
printf(" TCP Chksum : %d\n", shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
shortval = ntohs(shortval);
printf(" Urgent ptr : %d\n", shortval);

return 0;
}

//
// Function: DecodeIPHeader
//
// Description:
// This function takes a pointer to an IP header and prints
// it out in a readable form.
//
int DecodeIPHeader(WSABUF *wsabuf, unsigned int srcip, unsigned short srcport,
unsigned int destip, unsigned short destport)
{
BYTE *hdr = (BYTE *)wsabuf->buf,
*nexthdr = NULL;
unsigned short shortval;
SOCKADDR_IN srcaddr,
destaddr;

unsigned short ip_version,
ip_hdr_len,
ip_tos,
ip_total_len,
ip_id,
ip_flags,
ip_ttl,
ip_frag_offset,
ip_proto,
ip_hdr_chksum,
ip_src_port,
ip_dest_port;
unsigned int ip_src,
ip_dest;
BOOL bPrint = TRUE;


ip_version = HI_WORD(*hdr);
ip_hdr_len = LO_WORD(*hdr) * 4;
nexthdr = (BYTE *)(wsabuf->buf + ip_hdr_len);
hdr++;

ip_tos = *hdr;
hdr++;

memcpy(&shortval, hdr, 2);
ip_total_len = ntohs(shortval);
hdr += 2;

memcpy(&shortval, hdr, 2);
ip_id = ntohs(shortval);
hdr += 2;

ip_flags = ((*hdr) >> 5);

memcpy(&shortval, hdr, 2);
ip_frag_offset = ((ntohs(shortval)) & 0x1FFF);
hdr+=2;

ip_ttl = *hdr;
hdr++;

ip_proto = *hdr;
hdr++;

memcpy(&shortval, hdr, 2);
ip_hdr_chksum = ntohs(shortval);
hdr += 2;

memcpy(&srcaddr.sin_addr.s_addr, hdr, 4);
ip_src = ntohl(srcaddr.sin_addr.s_addr);
hdr += 4;

memcpy(&destaddr.sin_addr.s_addr, hdr, 4);
ip_dest = ntohl(destaddr.sin_addr.s_addr);
hdr += 4;
//
// If packet is UDP, TCP, or IGMP read ahead and
// get the port values.
//
if (((ip_proto == 2) ||
(ip_proto == 6) ||
(ip_proto == 17)) &&
bFilter)
{
memcpy(&ip_src_port, nexthdr, 2);
ip_src_port = ntohs(ip_src_port);
memcpy(&ip_dest_port, nexthdr+2, 2);
ip_dest_port = ntohs(ip_dest_port);

if ((srcip == ip_src) ||
(srcport == ip_src_port) ||
(destip == ip_dest) ||
(destport == ip_dest_port))
{
bPrint = TRUE;
}
else
{
bPrint = FALSE;
}

}
else if (bFilter)
bPrint = FALSE;

// Print IP Hdr
//
if (bPrint)
{
printf("IP HEADER\n");
printf(" IP Version: %-10d | IP Header Len: %2d bytes | IP TOS: %X%X (hex)\n",
ip_version, ip_hdr_len, HI_WORD(ip_tos), LO_WORD(ip_tos));
printf(" IP Total Len: %-05d bytes | Identification: 0x%08X | IP Flags: %X (hex)\n",
ip_total_len, ip_id, ip_flags);
printf(" Frag Offset: 0x%08X | TTL: %-10d | Protocol: %-10s \n",
ip_frag_offset, ip_ttl, szProto[ip_proto]);
printf(" Hdr Checksum: 0x%08X\n", ip_hdr_chksum);
printf(" Src Addr: %-15s\n", inet_ntoa(srcaddr.sin_addr));
printf(" Dest Addr: %-15s\n", inet_ntoa(destaddr.sin_addr));
}
else
return ip_hdr_len;

switch (ip_proto)
{
case 2: // IGMP
DecodeIGMPHeader(wsabuf, ip_hdr_len);
break;
case 6: // TCP
DecodeTCPHeader(wsabuf, ip_hdr_len);
break;
case 17: // UDP
DecodeUDPHeader(wsabuf, ip_hdr_len);
break;
default:
printf(" No decoder installed for protocol\n");
break;
}
printf("\n");

return ip_hdr_len;
}

//mstcpip.h
// Copyright (C) Microsoft Corporation, 1996-1999
#if _MSC_VER > 1000
#pragma once
#endif

/* Argument structure for SIO_KEEPALIVE_VALS */

struct tcp_keepalive {
u_long onoff;
u_long keepalivetime;
u_long keepaliveinterval;
};

// New WSAIoctl Options

#define SIO_RCVALL _WSAIOW(IOC_VENDOR,1)
#define SIO_RCVALL_MCAST _WSAIOW(IOC_VENDOR,2)
#define SIO_RCVALL_IGMPMCAST _WSAIOW(IOC_VENDOR,3)
#define SIO_KEEPALIVE_VALS _WSAIOW(IOC_VENDOR,4)
#define SIO_ABSORB_RTRALERT _WSAIOW(IOC_VENDOR,5)
#define SIO_UCAST_IF _WSAIOW(IOC_VENDOR,6)
#define SIO_LIMIT_BROADCASTS _WSAIOW(IOC_VENDOR,7)
#define SIO_INDEX_BIND _WSAIOW(IOC_VENDOR,8)
#define SIO_INDEX_MCASTIF _WSAIOW(IOC_VENDOR,9)
#define SIO_INDEX_ADD_MCAST _WSAIOW(IOC_VENDOR,10)
#define SIO_INDEX_DEL_MCAST _WSAIOW(IOC_VENDOR,11)

本原代码采用原始套接字，利用RECV_ALL,可截获IP，能分析IP,IGMP,TCP,UDP等包。

[florist2000]

前几天刚做了一套网络工具
一个功能就是这个，我用原始套节字做的
但是它有局限性。比如说－－不能捕捉数据链路层的数据报

[shen630]

我对数据链路层捕捉比较关心。
谁对win2000下ndis开发比较熟悉，希望能介绍介绍。

[florist2000]

呵呵，我做过一个局域网监视器
没有自己切入驱动
下载的别人的驱动包
很好用，你们可以试验

[newworld_ni]

对了，不知这边有谁对数据链路层的开发比较熟悉，希望能介绍介绍。