简易端口扫描器
在比较早以前，我用过S扫描器， 以及大名鼎鼎的nmap扫描器， 可以快速扫描某个主机开放的端口， 今天使用C实现这样一个软件，
编译环境为Mac， 系统版本10.11.6：
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
void msg()
{
printf("EP:scan ip startport endport\nEP:scan ip 127.0.0.1 20 2009\n");
}
int main(int argc,char** argv)
{
char *ip;
int startport,endport,sockfd,i;
struct sockaddr_in to;
float costtime;
clock_t start,end;
if(4!=argc)
{
msg();
return 0;
}
ip=argv[1];
startport=atoi(argv[2]);
endport=atoi(argv[3]);
if(startport<1 || endport>65535 || endport<startport)
{
printf("端口范围出错/n");
return 0;
}
else{
printf("IP:%s %d-%d\n",ip,startport,endport);
}
to.sin_family=AF_INET;
to.sin_addr.s_addr=inet_addr(ip);
start=clock();
for(i=startport;i<=endport;i++)
{
sockfd=socket(AF_INET,SOCK_STREAM,0);
to.sin_port=htons(i);
if(connect(sockfd,(struct sockaddr *)&to,sizeof(struct sockaddr)) == 0) {
printf("%s %d\n",ip,i);
close(sockfd);
};
}
end=clock();
costtime=(float)(end-start)/CLOCKS_PER_SEC;
printf("用时:%f秒\n",costtime);
return 0;
}亲测可行：
以上的代码只能检测固定的ip， 通过更改源码， 软件可以支持一段的ip端口检测， 多加一个循环：
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <string.h>
#include <fcntl.h>
#include <sys/select.h>
#include <string>
void msg()
{
printf( "EP:scan ip startport endport\nEP:scan ip 127.0.0.1 20 2009\n" );
printf( "EP:scan ip endip startport endport\nEP:scan ip 127.0.0. 250 20 2009\n" );
}
void runsock(int sockfd, struct sockaddr_in to, char *ipval, int i) {
sockfd = socket( AF_INET, SOCK_STREAM, 0 );
//fcntl(sockfd, F_SETFL, O_NONBLOCK);
to.sin_port = htons( i );
//printf( "IP:%s %d\n", ipval, i );
if ( connect( sockfd, (struct sockaddr *) &to, sizeof(struct sockaddr) ) == 0 ){
printf( "%s %d\n", ipval, i );
close( sockfd );
}
}
int main( int argc, char* argv[] ){
char * ip;
char * endip;
int startport, endport, sockfd, i;
struct sockaddr_in to;
float costtime;
clock_t start, end;
if ( 4 == argc ){
ip = argv[1];
startport = atoi( argv[2] );
endport = atoi( argv[3] );
if ( startport < 1 || endport > 65535 || endport < startport ){
printf( "端口范围出错/n" );
return(0);
}else{
printf( "IP:%s %d-%d\n", ip, startport, endport );
}
to.sin_family = AF_INET;
to.sin_addr.s_addr = inet_addr( ip );
start = clock();
for ( i = startport; i <= endport; i++ ){
runsock(sockfd, to, ip, i);
}
end = clock();
costtime = (float) (end - start) / CLOCKS_PER_SEC;
printf( "用时:%f秒\n", costtime );
return(0);
}else if ( 5 == argc ){
ip = argv[1];
endip = argv[2];
startport = atoi( argv[3] );
endport = atoi( argv[4] );
char *tempip;
if ( startport < 1 || endport > 65535 || endport < startport ){
printf( "端口范围出错/n" );
return(0);
}else{
/* 循环ip地址 */
start = clock();
char ipval[20];
for ( int j = 1; j <= atoi( endip ); j++ ){
sprintf( ipval, "%s%d", ip, j );
printf( "IP:%s\n", ipval );
to.sin_family = AF_INET;
to.sin_addr.s_addr = inet_addr( ipval );
for ( i = startport; i <= endport; i++ ){
runsock(sockfd, to, ipval, i);
}
}
end = clock();
costtime = (float) (end - start) / CLOCKS_PER_SEC;
printf( "用时:%f秒\n", costtime );
};/* 循环端口 */
return(0);
}
msg();
return(0);
}局域网网段IP端口扫描器
看起来这个扫描器是实现了， 但是还有一个天大的问题， 那就是connect是同步的， 如果有些ip是不存在的， 那么connect函数就会阻塞在那边， 导致运行非常缓慢，那就需要异步的socket连接， 涉及select.h， 通过icmp判断存活主机：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <signal.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <setjmp.h>
#include <errno.h>
#include <sys/select.h>
#include <fcntl.h>
#define PACKET_SIZE 4096
/* 计算校验和的算法 */
unsigned short cal_chksum(unsigned short *addr,int len)
{
int sum=0;
int nleft = len;
unsigned short *w = addr;
unsigned short answer = 0;
/* 把ICMP报头二进制数据以2字节为单位累加起来 */
while(nleft > 1){
sum += *w++;
nleft -= 2;
}
/*
* 若ICMP报头为奇数个字节，会剩下最后一字节。
* 把最后一个字节视为一个2字节数据的高字节，
* 这2字节数据的低字节为0，继续累加
*/
if(nleft == 1){
*(unsigned char *)(&answer) = *(unsigned char *)w;
sum += answer; /* 这里将 answer 转换成 int 整数 */
}
sum = (sum >> 16) + (sum & 0xffff); /* 高位低位相加 */
sum += (sum >> 16); /* 上一步溢出时，将溢出位也加到sum中 */
answer = ~sum; /* 注意类型转换，现在的校验和为16位 */
return answer;
}
int livetest(char* ip) {
char sendpacket[PACKET_SIZE]; /* 发送的数据包 */
char recvpacket[PACKET_SIZE]; /* 接收的数据包 */
pid_t pid;
int datalen = 56; /* icmp数据包中数据的长度 */
struct protoent *protocol;
protocol = getprotobyname("icmp");
int sockfd;
int size = 50*1024;
if((sockfd = socket(AF_INET, SOCK_RAW, protocol->p_proto)) < 0) {
perror("socket error");
}
setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size) );
struct sockaddr_in dest_addr;
bzero(&dest_addr, sizeof(dest_addr));
dest_addr.sin_family = AF_INET;
dest_addr.sin_addr.s_addr = inet_addr(ip);
//send packet;
int packsize;
struct icmp *icmp;
struct timeval *tval;
icmp = (struct icmp*)sendpacket;
icmp->icmp_type = ICMP_ECHO; /* icmp的类型 */
icmp->icmp_code = 0; /* icmp的编码 */
icmp->icmp_cksum = 0; /* icmp的校验和 */
icmp->icmp_seq = 1; /* icmp的顺序号 */
icmp->icmp_id = pid; /* icmp的标志符 */
packsize = 8 + datalen; /* icmp8字节的头 加上数据的长度(datalen=56), packsize = 64 */
tval = (struct timeval *)icmp->icmp_data; /* 获得icmp结构中最后的数据部分的指针 */
gettimeofday(tval, NULL); /* 将发送的时间填入icmp结构中最后的数据部分 */
icmp->icmp_cksum = cal_chksum((unsigned short *)icmp, packsize);/*填充发送方的校验和*/
if(sendto(sockfd, sendpacket, packsize, 0, (struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0){
perror("sendto error");
}
//printf("send %d, send done\n",1 );
int n;
struct sockaddr_in from;
int fromlen = sizeof(from);
fcntl(sockfd, F_SETFL, O_NONBLOCK);
struct timeval timeo = {1,0};
fd_set set;
FD_ZERO(&set);
FD_SET(sockfd, &set);
//read , write;
int retval = select(sockfd+1, &set, NULL, NULL, &timeo);
if(retval == -1) {
printf("select error\n");
return 0;
}else if(retval == 0 ) {
//printf("timeout\n");
return 0;
}else{
if( FD_ISSET(sockfd, &set) ){
//printf("host is live\n");
return 1;
}
return 0;
}
// n = recvfrom(sockfd, recvpacket,sizeof(recvpacket), 0, (struct sockaddr *)&from, (socklen_t *)&fromlen);
// if(n<0) {
// perror("recvfrom error");
// }else{
// printf("%d\n",n);
// }
//return 0;
}
static void sleep_ms(unsigned int secs){
struct timeval tval;
tval.tv_sec=secs/1000;
tval.tv_usec=(secs*1000)%1000000;
select(0,NULL,NULL,NULL,&tval);
}
void msg()
{
printf( "EP:scan ip startport endport\nEP:scan ip 127.0.0.1 20 2009\n" );
printf( "EP:scan ip endip startport endport\nEP:scan ip 127.0.0. 1 250 20 2009\n" );
}
void runsock(int sockfd, struct sockaddr_in to, char *ipval, int i) {
sockfd = socket( AF_INET, SOCK_STREAM, 0 );
fcntl(sockfd, F_SETFL, O_NONBLOCK);
fd_set set,writeSet;
int error; //错误代码
socklen_t len = sizeof(error);
//while(1){
FD_ZERO(&set);
FD_ZERO(&writeSet);
struct timeval timeo= {1,0};
//socklen_t len = sizeof(timeo);
FD_SET(sockfd,&set);
FD_SET(sockfd,&set);
//setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO,&timeo, len);
to.sin_port = htons( i );
//printf( "test %s %d , sockfd value %d\n", ipval, i , sockfd);
//printf( "IP:%s %d\n", ipval, i );
//printf("%d\n",i);
int conn = connect( sockfd, (struct sockaddr *) &to, sizeof(struct sockaddr) );
//等待
int retval = select(sockfd+ 1, &set, &writeSet, NULL, &timeo);
getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len );
if(error == 0)
printf("%s Port %d is opened\n", ipval, i);
//printf("%d\n",sockfd);
// printf("%s :%d\n",ipval, i);
// if (retval== -1) {
// perror("select error\n");
// } else if(retval == 0){
// //printf("timeout\n");
// }else{
// //printf("find %s :%d\n",ipval, i);
// if(FD_ISSET(sockfd,&set)) {
// printf("find %s :%d\n",ipval, i);
// }
// }
//}
}
int main( int argc, char* argv[] ){
char * ip;
int endip, startip;
int startport, endport, sockfd, i;
struct sockaddr_in to;
float costtime;
clock_t start, end;
if ( 4 == argc ){
ip = argv[1];
startport = atoi( argv[2] );
endport = atoi( argv[3] );
if ( startport < 1 || endport > 65535 || endport < startport ){
printf( "端口范围出错/n" );
return(0);
}else{
printf( "IP:%s %d-%d\n", ip, startport, endport );
}
to.sin_family = AF_INET;
to.sin_addr.s_addr = inet_addr( ip );
start = clock();
for ( i = startport; i <= endport; i++ ){
//printf("%d\n",i);
runsock(sockfd, to, ip, i);
}
end = clock();
costtime = (float) (end - start) / CLOCKS_PER_SEC;
printf( "用时:%f秒\n", costtime );
return(0);
}else if ( 6 == argc ){
ip = argv[1];
startip = atoi(argv[2]);
endip = atoi(argv[3]);
startport = atoi( argv[4] );
endport = atoi( argv[5] );
char *tempip;
if ( startport < 1 || endport > 65535 || endport < startport ){
printf( "端口范围出错/n" );
return(0);
}else{
/* 循环ip地址 */
start = clock();
char ipval[20];
for ( int j = startip; j <= endip ; j++ ){
sprintf( ipval, "%s%d", ip, j );
printf( "IP:%s\n", ipval );
if(livetest(ipval) == 1){
to.sin_family = AF_INET;
//printf("okokok\n");
to.sin_addr.s_addr = inet_addr( ipval );
for ( i = startport; i <= endport; i++ ){
runsock(sockfd, to, ipval, i);
sleep_ms(1000);
}
}
}
end = clock();
costtime = (float) (end - start) / CLOCKS_PER_SEC;
printf( "用时:%f秒\n", costtime );
};
//while(1){}
/* 循环端口 */
return(0);
}
msg();
return(0);
}
使用方式1： scan ip startport endport
sudo ./s 192.168.2.114 1 139
使用方式2: scan ip start endip startport endport
sudo ./s 192.168.1. 108 110 1 200
还有一个问题， 就是扫描的端口不怎么准确， 经常出现误报， 有些端口跟没开， 但是扫描器会显示目标端口有开， 应该是判断sock是否连接成功的逻辑有问题， 目前没有好的解决方案， 期待大神指点一下：
getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &len );
if(error == 0)
printf("%s Port %d is opened\n", ipval, i);EOF
作者： NONO
