linux下的connect連接埠掃描程式

#include<unistd.h>#include<stdio.h>#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<netdb.h>int main(int argc,char *argv[]){if(argc!=4){printf("please input %s <host> <start> and <end> port\n",argv[0]);return 0;}int sport=atoi(argv[2]),eport=atoi(argv[3]);int sockfd,num;struct hostent *he;struct sockaddr_in server;struct servent *sp;if((he=gethostbyname(argv[1]))==NULL){printf("gethostbyname error\n");return 0;}for(int i=sport;i<=eport;i++){if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1){printf("socket() error\n");return 0;}bzero(&server,sizeof(server));server.sin_family = AF_INET;server.sin_port = htons(i);server.sin_addr.s_addr = inet_addr(argv[1]);if(connect(sockfd,(struct sockaddr*)&server,sizeof(server))==-1){close(sockfd);}else{sp=getservbyport(server.sin_port,"tcp");printf("Port %d is open.%s\n",i,(sp==NULL)?"unknow ":sp->s_name);}close(sockfd);}return 1;}

僅對同一網段內的主機有效。