linux伪装网关给自己发 ICMP重定向数据包 路由表没有变化 WHY?
本帖最后由 626788149 于 2014-10-16 13:06 编辑#include<stdlib.h>
#include<sys/socket.h>
#include<netinet/ip_icmp.h>
#include<netinet/in.h>
#include<netinet/udp.h>
#include<netinet/ip.h>
void send_icmptime(int sockfd, struct sockaddr *sa, socklen_t len);
uint16_t in_cksum(uint16_t *addr, int len);
#define MAXLINE 1024
void main()
{
int sockfd;
struct sockaddr_in sin;
sin.sin_family = AF_INET;
struct addrinfo *ai;
int on =1;
inet_pton(AF_INET, "186.9.9.9", &sin.sin_addr);
if( (sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
perror("socket");
if( setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &on, sizeof(int)) < 0)
perror("setsockopt");
send_icmptime(sockfd, (struct sockaddr *)&sin, sizeof(sin));
}
void send_icmptime(int sockfd, struct sockaddr *s, socklen_t len)
{
struct in_addr myaddr;
inet_pton(AF_INET, "172.21.203.91", &myaddr);
struct icmp *icmp;
struct timeval val;
struct ip *ip1;
ip1 = (struct ip *)malloc(56);
ip1->ip_v = 4;
ip1->ip_hl = 5;
ip1->ip_tos = 0;
ip1->ip_len = 56;
ip1->ip_id = 0;
ip1->ip_off = 0;
ip1->ip_ttl = 64;
ip1->ip_p = IPPROTO_ICMP;
ip1->ip_sum = 0;
inet_pton(AF_INET, "119.75.217.96", &ip1->ip_src);
inet_pton(AF_INET, "127.0.0.1", &ip1->ip_dst);
icmp = (struct icmp *)((char *)ip1 + 20);
icmp->icmp_type = ICMP_REDIRECT;
icmp->icmp_code = ICMP_REDIRECT_HOST;
icmp->icmp_cksum = 0;
icmp->icmp_gwaddr = myaddr;
struct ip *ip;
ip = (struct ip *)((char *)icmp + 8);
ip->ip_v = 4;
ip->ip_hl = 5;
ip->ip_tos = 0;
ip->ip_len = htons(55);
ip->ip_id = 0;
ip->ip_off = 0;
ip->ip_ttl = 54;
ip->ip_p = IPPROTO_UDP;
ip->ip_sum = 0;
inet_pton(AF_INET, "172.21.202.14", &ip->ip_src);
inet_pton(AF_INET, "172.21.202.91", &ip->ip_dst);
ip->ip_sum = in_cksum((u_short *)ip, 20);
struct udphdr *udp;
udp = (struct udphdr*)((char *)ip + 20);
udp->uh_sport =6666;
udp->uh_dport =6666;
udp->uh_ulen = htons(55);
udp->uh_sum = in_cksum((u_short *)udp, 8);
icmp->icmp_cksum = in_cksum((u_short *)icmp, 36);
if(sendto(sockfd, ip1, 56, 0 ,s, len) < 0)
perror("sendto");
}
uint16_t in_cksum(uint16_t *addr, int len)
{
int nleft = len;
uint32_t sum = 0;
uint16_t *w = addr;
uint16_t answer = 0;
while(nleft > 1)
{
sum += *w++;
nleft -= 2;
}
if(nleft == 1)
{
*(unsigned char *)(&answer) = *(unsigned char *)w;
sum += answer;
}
sum = ( sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer =~sum;
return answer;
}
root@zz-E431:/home/zz# tcpdump -i ppp0 icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
13:01:46.891807 IP 119.75.217.96 > localhost: ICMP redirect 172.21.202.91 to host 172.21.203.91, length 36
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