#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
 
int main(void)
{
  #define sHELLO "123"
  struct sockaddr_in stSockAddr;
  int i32SocketFD = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
 
  if(-1 == i32SocketFD)
  {
    perror("Ne mogy sozdat socket");
    exit(EXIT_FAILURE);
  }
 
  memset(&stSockAddr, 0, sizeof(stSockAddr));
 
  stSockAddr.sin_family = PF_INET;
  stSockAddr.sin_port = htons(1111);
  stSockAddr.sin_addr.s_addr = INADDR_ANY;
 
  if(-1 == bind(i32SocketFD,(const void *)&stSockAddr, sizeof(stSockAddr)))
  {
    perror("Oshibka svazivaniya");
    close(i32SocketFD);
    exit(EXIT_FAILURE);
  }
 
  if(-1 == listen(i32SocketFD, 10))
  {
    perror("Oshibka proslushivaniya");
    close(i32SocketFD);
    exit(EXIT_FAILURE);
  }
 
  for(;;)
  {
    int i32ConnectFD = accept(i32SocketFD, NULL, NULL);
 
    if(0 > i32ConnectFD)
    {
      perror("Oshibka prinatya");
      close(i32ConnectFD);
      close(i32SocketFD);
      exit(EXIT_FAILURE);
    }

    // отправляем клиенту приветствие
    send(i32SocketFD, sHELLO, sizeof(sHELLO), 0);
     close(i32ConnectFD);
  }
  return 0;
}

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
 
int main(void)
{
  char sHELLO[20];
  struct sockaddr_in stSockAddr;
  int i32Res;
  int i32SocketFD = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
  if(-1 == i32SocketFD)
  {
    perror("Oshibka ne mogy sozdat soket");
    exit(EXIT_FAILURE);
  }
 
  memset(&stSockAddr, 0, sizeof(stSockAddr));
 
  stSockAddr.sin_family = PF_INET;
  stSockAddr.sin_port = htons(1111);
  i32Res = inet_pton(PF_INET, "127.0.0.1", &stSockAddr.sin_addr);
 
  if(0 > i32Res)
  {
    perror("Pervii parametr ne otnositsa k kotegorii nor adresov");
    close(i32SocketFD);
    exit(EXIT_FAILURE);
  }
  else if(0 == i32Res)
  {
    perror("char string (Ne sodergit norm 2 ip");
    close(i32SocketFD);
    exit(EXIT_FAILURE);
  }
 
  if(connect(i32SocketFD, (const void *)&stSockAddr, sizeof(stSockAddr))==-1)
  {
    perror("oshibka soedineniya");
    close(i32SocketFD);
    exit(EXIT_FAILURE);
  }
   
  close(i32SocketFD);
  printf("\n%s\n",sHELLO);
  printf("\n");
  return 0;
}