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#include "unp.h"
#define MAXPORT 1000
extern int errno;
int main(int argc,char **argv){
int sockfd,ret;
struct sockaddr_in servaddr;
if (argc != 3)
err_quit("usage: a.out <IPaddress> <port>");
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
err_quit("inet_pton error for %s", argv[1]);
printf("conneting to port %s \n",argv[2]);
servaddr.sin_port = htons(atoi(argv[2]));
if (ret=connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) >= 0)
{
printf("port %s is open \n",argv[2]);
}
printf("return %d\n",ret);
printf("errno:%d",errno);
err_sys("errno:");
exit(0);
}
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sam@sam-desktop:~/unpv13e/example$ ./test 9.125.129.169 80
conneting to port 80
port 80 is open
return 1
errno:0errno:: Success
sam@sam-desktop:~/unpv13e/example$ ./test 9.125.129.169 79
conneting to port 79
return 0
errno:111errno:: Connection refused
sam@sam-desktop:~/unpv13e/example$ ./test 9.125.129.169 21
conneting to port 21
return 0
errno:111errno:: Connection refused
sam@sam-desktop:~/unpv13e/example$ ./test 9.125.129.169 20
conneting to port 20
ctrl+C
sam@sam-desktop:~/unpv13e/example$ ./test 9.125.129.169 19
conneting to port 19
ctrl+C
连接20以下端口时,长时间没有反应。也不报 Connection refused。为啥? |
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