How can I run server and client applications in two different computers?

From: learning_C++ (learning_c_at_hotmail.com)
Date: 09/27/04 

Date: 27 Sep 2004 07:11:20 -0700

Hi,
I found some example code about server and client applications. But I
can not run server and client in different computers. Now, I only
run them in the different windows in Linux. I hope to I can log on a
computer that run server application from a different computer. How
can I modify those codes?

Thanks,

/*server.c*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#define MYPORT 3490 // the port users will be connecting to
#define BACKLOG 10 // how many pending connections queue will hold
void sigchld_handler(int s) {
  while(wait(NULL) > 0);
}
int main(void) {
  int sockfd, new_fd; // listen on sock_fd, new connection on new_fd
  struct sockaddr_in my_addr; // my address information
  struct sockaddr_in their_addr; // connector s address information
  int sin_size;
  struct sigaction sa;
  int yes=1;
  
  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    { perror("socket"); exit(1);
    }
  if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) ==
-1) {
    perror("setsockopt");
    exit(1);
  }
  my_addr.sin_family = AF_INET; // host byte order
  my_addr.sin_port = htons(MYPORT); // short, network byte order
  my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my
IP
  memset(&(my_addr.sin_zero), '\0' , 8); // zero the rest of the
struct
  
  if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct
sockaddr)) == -1) {
    perror("bind"); exit(1);
  } if (listen(sockfd, BACKLOG) == -1) {
    perror("listen");
    exit(1);
  }
  sa.sa_handler = sigchld_handler; // reap all dead processes
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = SA_RESTART;
  if (sigaction(SIGCHLD, &sa, NULL) == -1) {
    perror("sigaction");
 exit(1);
  }

  while(1) { // main accept() loop
    sin_size = sizeof(struct sockaddr_in);
    if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr,
&sin_size)) == -1) {
      perror("accept");
      continue; }
    printf("server: got connection from %s\n",
inet_ntoa(their_addr.sin_addr));
    if (!fork()) { // this is the child process
      close(sockfd); // child doesn t need the listener
      if (send(new_fd, "Hello, world!\n", 14, 0) == -1)
 perror("send");
      close(new_fd);
      exit(0);
    } close(new_fd); // parent doesn't need this
  } return 0;
}

/* ** client.c - a stream socket client demo */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define PORT 3490 // the port client will be connecting to
#define MAXDATASIZE 100 // max number of bytes we can get at once
int main(int argc, char *argv[]) {
  int sockfd, numbytes;
  char buf[MAXDATASIZE];
  struct hostent *he;
  struct sockaddr_in their_addr; // connector s address information
  if (argc != 2) {
    fprintf(stderr,"usage: client hostname\n");
    exit(1);
  }
  if ((he=gethostbyname(argv[1])) == NULL) { // get the host info
    perror("gethostbyname");
    exit(1);
  }
  
  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("socket");
    exit(1);
  }
  their_addr.sin_family = AF_INET; // host byte order
  their_addr.sin_port = htons(PORT); // short, network byte order
  their_addr.sin_addr = *((struct in_addr *)he->h_addr);
  memset(&(their_addr.sin_zero), '\0' , 8); // zero the rest of the
struct
  if (connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct
sockaddr)) == -1) {
    perror("connect");
    exit(1);
  }
  if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
    perror("recv");
    exit(1);
  }
  buf[numbytes] = '\0' ;
  printf("Received: %s",buf);
  close(sockfd);
  return 0;
}

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