目前，國內推出了許多的Linux的發行版本，其重點集中在中文平台上，方便了國內用戶對Linux的使用，但是有一個不是太好的跡象就是把漢化作為Linux操作系統的主要功能，實際上漢字處理盡管非常重要，但是把Linux作為桌面系統進行推廣，其價值不是非常大，並且在推出的發行版本中，應用程序的源代碼包多被刪除，而選擇了一些不是太有價值的X-Windows程序包，而許多應用程序（如PHP3）必須要源代碼的支持才可進行功能的擴展，GNU/Linux的優秀主要是給了我們非常豐富的軟件資源，和享受資源的充分自由，應用程序的分析難度遠小於內核，並且能夠帶來比較明顯的效果，實際上許多的應用程序都提供了多平台的支持。Linux目前可能作為對抗Windows NT的工具是非常合適的。
附源程序：
/*
* This program demonstrate SOCK_PACK call.
* Thanks Linux. Thanks Alan Cox
* derived from/usr/src/redhat/SOURCES/dosemu-0.66.7/src/dosext/net/net/libpacket.c
* compile method： cc capturer.c -o capturer
*/
/*
* Alan Cox raw code
*/
/*
* SOCK_PACKET support.
* Placed under the GNU LGPL.
*
* First cut at a library of handy support routines. Comments, additions
* and bug fixes greatfully received.
*
* (c) 1994 Alan Cox [email protected] GW4PTS@GB7SWN
*/
#include <stdio.h>
#include <features.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <getopt.h>
#include <string.h>
#include <fcntl.h>
#include <asm/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
/*#if __GLIBC__ > 1*/
#include <asm/sockios.h>
#include <net/if.h>
/*#else
#include <linux/sockios.h>
#include <linux/if.h>
#endif*/
#include <netinet/in.h>
#include <asm/checksum.h>
/*
* Obtain a file handle on a raw ethernet type. In actual fact
* you can also request the dummy types for AX.25 or 802.3 also
*
* -1 indicates an error
* 0 or higher is a file descriptor which we have set non blocking
*
* WARNING: It is ok to listen to a service the system is using (eg arp)
* but don't try and run a user mode stack on the same service or all
* hell will break loose.
*/
int
OpenNetworkType(unsigned short netid)
{
int s = socket(AF_INET, SOCK_PACKET, htons(netid));
if (s == -1)
return -1;
fcntl(s, F_SETFL, O_NDELAY);
return s;
}
/*
* Close a file handle to a raw packet type.
*/
void
CloseNetworkLink(int sock)
{
close(sock);
}
/*
* Write a packet to the network. You have to give a device to
* this function. This is a device name (eg 'eth0' for the first
* ethernet card). Please don't assume eth0, make it configurable
* - plip is ethernet like but not eth0, ditto for the de600's.
*
* Return: -1 is an error
* otherwise bytes written.
*/
int
WriteToNetwork(int sock, const char *device, const char *data, int len)
{
struct sockaddr sa;
sa.sa_family = AF_INET;
strcpy(sa.sa_data, device);
return (sendto(sock, data, len, 0, &sa, sizeof(sa)));
}
/*
* Read a packet from the network. The device parameter will
* be filled in by this routine (make it 32 bytes or more).
* If you wish to work with one interface only you must filter
* yourself. Remember to make your buffer big enough for your
* data. Oversized packets will be truncated.
*
* Return:
* -1 Error
* otherwise Size of packet received.
*/
int
ReadFromNetwork(int sock, char *device, char *data, int len)
{
struct sockaddr sa;
int sz = sizeof(sa);
int error;
error = recvfrom(sock, data, len, 0, &sa, &sz);
if (error == -1)
return -1;
strcpy(device, sa.sa_data);
return error; /* Actually size of received packet */
}
/*
* Handy support routines.
*/
/*
* Obtain the hardware address of an interface.
* addr should be a buffer of 8 bytes or more.
*
* Return:
* 0 Success, buffer holds data.
* -1 Error.
*/
/*
* NET2 or NET3 - work for both.
*/
#if defined(OLD_SIOCGIFHWADDR) || (KERNEL_VERSION >= 1003038)
#define NET3
#endif
int
GetDeviceHardwareAddress(char *device, char *addr)
{
int s = socket(AF_INET, SOCK_DGRAM, 0);
struct ifreq req;
int err;
strcpy(req.ifr_name, device);
err = ioctl(s, SIOCGIFHWADDR, &req);
close(s); /* Thanks Rob. for noticing this */
if (err == -1)
return err;
memcpy(addr, req.ifr_hwaddr.sa_data,8);
return 0;
}
/*
* Obtain the maximum packet size on an interface.
*
* Return:
* >0 Return is the mtu of the interface
* -1 Error.
*/
int
GetDeviceMTU(char *device)
{
int s = socket(AF_INET, SOCK_DGRAM, 0);
struct ifreq req;
int err;
strcpy(req.ifr_name, device);
err = ioctl(s, SIOCGIFMTU, &req);
close(s); /* So I'll add this one as well. Ok Alan? - Rob */
if (err == -1)
return err;
return req.ifr_mtu;
}
#define data_packet_len 1514
int
main(int argc ,char *argv[])
{
char devicename_rec[32];
unsigned char data[data_packet_len];
int netid=0x03,sock_h=0,i=0,count_rec=0;
if ((sock_h=OpenNetworkType(netid))<0)
{
printf("Can't open net_dectype %d
",netid);
return -1;
}
printf("Ready to receive 0x%x data packet...
",netid);
for(;;) {
if (ReadFromNetwork(sock_h,devicename_rec,data,data_packet_len)>0) {
printf("Received Packet = %d
",++count_rec) ;
for (i=0;i<100;i++)
printf("%2x|",data[i]);
printf("
");
}
}
}
以上程序在Redhat 5.1下編譯通過，運行良好。