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Determining the IP address of a connected client on a server

I have a server running on one computer, and the port that it uses is redirected to my router, and another computer with a client connecting to the server using my IP address assigned by ISP instead of the local address. All this works fine and connects, but when I check the address of the connected socket (client), the displayed IP address is completely different? he shows me 148.49.68.0. I can not find this on ipconfig and do not understand where this is coming from. Shouldn't the client show my external address? (seeing that both computers use the same external IP address).

[EDIT] added server source

#include <iostream>
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <string.h>
using namespace std;

int PORT;
const int winsock_version = 2;
const int max_con = 10;
string SERVER_ADDRS;

void Bind(SOCKET &serv,struct sockaddr_in &serv_info,int size);
void Listen(SOCKET &serv,int max_con);
void connection_info(struct sockaddr_in &client);
bool communication(SOCKET &client); 
SOCKET Accept(SOCKET &serv);

int main(void){

    WSADATA wsadata;
    if ( WSAStartup(MAKEWORD(winsock_version,0),&wsadata) == 0 ){
        cout<<"-[Initialized.]" << endl;
        cout<<"-[Server Address (leave blank to scan for all IP's)]: ";
        getline(cin,SERVER_ADDRS);
        cout<<"-[Port]: ";
        cin>>PORT;

        struct sockaddr_in serv_info;
        serv_info.sin_family = AF_INET;
        serv_info.sin_port = htons(PORT);
        if( sizeof(SERVER_ADDRS) > 5 ){
            cout<<"-[Listening on: " << SERVER_ADDRS << "]" << endl;
            serv_info.sin_addr.s_addr = inet_addr(SERVER_ADDRS.c_str());
        }else{
            cout<<"-[Scanning for All IP's]" << endl;
            serv_info.sin_addr.s_addr = INADDR_ANY;
        }

        SOCKET serv;
        serv = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
        if ( serv != INVALID_SOCKET ){
            //------------------------------------------------------------
            Bind(serv,serv_info,sizeof(serv_info));
            Listen(serv,max_con);


            struct sockaddr_in client_info;
            int size = sizeof(client_info);

            SOCKET client_sock = Accept(serv);
            connection_info(client_info);

            if (communication(client_sock) == true){
                closesocket(serv);
                closesocket(client_sock);
            }
            //------------------------------------------------------------
        }

    }else{
        cout<<"-[Initialization failed, running cleanup.]" << endl;
    }

    if (WSACleanup() == 0){
        cout<<"-[Cleanup Successful.]" << endl;
    }

    return 0;
}

void Bind(SOCKET &serv,struct sockaddr_in &serv_info,int size){

    if ( bind(serv,(sockaddr*)&serv_info,size) != -1 ){
        //Binding complete, now clear the port and allow for reuse if needed using setsockopt
        char yes = '1';
        if ( setsockopt(serv,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) != SOCKET_ERROR){
                cout<<"-[Binding Successful.]" << endl;
        }
    }
}

void Listen(SOCKET &serv,int max_con){
    if ( listen(serv,max_con) != -1 ){
        cout<<"-[Listening for connections.] " << endl;
    }
}

SOCKET Accept(SOCKET &serv){

    struct sockaddr_in client_info;
    int size = sizeof(client_info);
    SOCKET recv;

    recv = accept(serv,(sockaddr*)&client_info,&size);
    if (recv != INVALID_SOCKET ) {
        return recv;
    }else{
        cout<<"-[Invalid Socket.]" << endl;
    }
}

void connection_info(struct sockaddr_in &client){
    char *connected_ip= inet_ntoa(client.sin_addr); 
    int port = ntohs(client.sin_port);

    cout<<"-[IP:" << connected_ip <<", Connected on PORT:"<< port  << "]"<< endl;
}

bool communication(SOCKET &client){
    cout<<"[---------------{CHAT}---------------]" << endl;
    int bytes_in;
    int bytes_out;
    char recvd_text[80];
    string send_text;

    while(true){
        cout<<"-[SERVER]: ";
        getline(cin,send_text);
        if (sizeof(send_text) > 0 ){
            bytes_out = send(client,send_text.c_str(),send_text.length()+1,0);
            cout<< endl;
            if (bytes_out == SOCKET_ERROR){
                cout<<"-[SERVER error in sending.]" << endl;
                break;
            }
        }

        bytes_in = recv(client,recvd_text,sizeof(recvd_text),0);
        if (bytes_in > 0 ){
            cout<<"-[CLIENT]: " << recvd_text << endl;  //output on screen
        }
        if (bytes_in == 0){
            cout<<"-[CLIENT has disconnected.]" << endl;
            break;
        }
        if (bytes_in == SOCKET_ERROR){
            cout<<"-[CLIENT closed unexpectedly.]" << endl; 
            break;
        }

    }
    return true;
}
+3
4

:

#include <iostream>
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <string>

int PORT;
const int winsock_version = 2;
const int max_con = 10;
std::string SERVER_ADDRS;

void Bind(SOCKET &serv, const struct sockaddr_in &serv_info);
void Listen(SOCKET &serv, int max_con);
void connection_info(struct sockaddr_in &client);
bool communication(SOCKET client);
SOCKET Accept(SOCKET serv, sockaddr_in &client_info); 

int main(void)
{
    WSADATA wsadata; 
    if ( WSAStartup(MAKEWORD(winsock_version,0),&wsadata) == 0 )
    { 
        std::cout << "-[Initialized.]" << std::endl; 
        std::cout << "-[Server Address (leave blank to scan for all IP's)]: "; 
        std::getline(std::cin, SERVER_ADDRS); 
            std::cout << "-[Port]: "; 
        std::cin >> PORT; 

        struct sockaddr_in serv_info = {0}; 
        serv_info.sin_family = AF_INET; 
        serv_info.sin_port = htons(PORT); 
        if( SERVER_ADDRS.length() > 0 )
        { 
            std::cout << "-[Listening on: " << SERVER_ADDRS << "]" << std::endl; 
            serv_info.sin_addr.s_addr = inet_addr(SERVER_ADDRS.c_str()); 
        }
        else
        { 
            std::cout << "-[Scanning for All IP's]" << std::endl; 
            serv_info.sin_addr.s_addr = INADDR_ANY; 
        } 

        SOCKET serv = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); 
        if ( serv != INVALID_SOCKET )
        { 
            //------------------------------------------------------------ 
            Bind(serv, serv_info); 
            Listen(serv, max_con); 

            struct sockaddr_in client_info = {0}; 

            SOCKET client_sock = Accept(serv, client_info);
            if ( client_sock != INVALID_SOCKET )
            {
                connection_info(client_info); 
                communication(client_sock);

                closesocket(client_sock); 
            }
            //------------------------------------------------------------ 

            closesocket(serv); 
        } 


        if (WSACleanup() == 0)
        { 
            std::cout << "-[Cleanup Successful.]" << std::endl; 
        }
    }
    else
    { 
        std::cout << "-[Initialization failed.]" << std::endl; 
    } 

    return 0; 
} 

void Bind(SOCKET serv, const struct sockaddr_in &serv_info)
{ 
    //clear the port and allow for reuse before binding it
    int yes = 1; 
    if ( setsockopt(serv, SOL_SOCKET, SO_REUSEADDR, (char*)&yes, sizeof(yes)) != SOCKET_ERROR)
    {
        std::cout << "-[Reuse Address Successful.]" << std::endl; 
    }

    if ( bind(serv, (sockaddr*)&serv_info, sizeof(serv_info)) != -1 )
    { 
        std::cout << "-[Binding Successful.]" << std::endl; 
    } 
} 

void Listen(SOCKET serv, int max_con)
{ 
    if ( listen(serv, max_con) != -1 )
    { 
        std::cout << "-[Listening for connections.] " << std::endl; 
    } 
} 

SOCKET Accept(SOCKET &serv, sockaddr_in &client_info)
{ 
    int size = sizeof(client_info); 
    SOCKET recv = accept(serv, (sockaddr*)&client_info, &size); 
    if ( recv == INVALID_SOCKET )
    { 
            std::cout << "-[Invalid Socket.]" << std::endl; 
    } 
    return recv; 
} 

void connection_info(struct sockaddr_in &client)
{ 
    char *connected_ip = inet_ntoa(client.sin_addr);
    int port = ntohs(client.sin_port); 

    st::cout << "-[IP:" << connected_ip << ", Connected on PORT:" << port << "]" << std::endl; 
} 

bool communication(SOCKET client)
{ 
    std::cout << "[---------------{CHAT}---------------]" << std::endl; 
    int bytes_in; 
    int bytes_out; 
    char recvd_text[81]; 
    std::string send_text; 

    while(true)
    { 
        std::cout << "-[SERVER]: "; 
        std::getline(std::cin,send_text); 
        if (send_text.length() > 0 )
        { 
            bytes_out = send(client, send_text.c_str(), send_text.length()+1, 0); 
            std::cout << std::endl; 
            if (bytes_out == SOCKET_ERROR)
            { 
                std::cout << "-[SERVER error in sending.]" << std::endl; 
                break; 
            } 
        } 

        bytes_in = recv(client, recvd_text, sizeof(recvd_text)-1, 0); 
        if (bytes_in == SOCKET_ERROR)
        { 
            std::cout << "-[CLIENT closed unexpectedly.]" << std::endl; 
            break; 
        } 
        else if (bytes_in == 0)
        { 
            std::cout << "-[CLIENT has disconnected.]" << std::endl; 
            break; 
        } 
        else
        {
            recvd_text[bytes_in] = 0;
            std::cout << "-[CLIENT]: " << recvd_text << std::endl;  //output on screen 
        }
    } 
    return true; 
}
+8

WinSock getsockname() getpeername() IP- . , , , , , , .

0

enter image description here

ip - c/++ - - API IP-, -, IP-, char IP- HTML. Winsock, . http://api.ipify.org/ - api.

//
// Winsock get external ip address from website api at   api.ipify.org
// api.ipify.org
//

#include <string.h>
#include <stdio.h>

#include <winsock2.h>
#include <windows.h>
#include <iostream>
#include <vector>

#include <algorithm>
#include <cctype>
#include <locale>
#include <fstream>
#include <ctime>
#include <cstdlib>

using namespace std;
#pragma comment(lib,"ws2_32.lib")


string website_HTML;
locale local;
char ipaddress[16];
int ic=0;
void get_Website(char *url );
char mystring[] = " ";
char seps[]   = " ,\t\n";
char *token;
char lineBuffer[200][80] ={' '};
char buffer[10000];
char ip_address[16];
int i = 0, bufLen=0, j=0,lineCount=0;
int lineIndex=0, posIndex=0;


int main( void ){

    SYSTEMTIME st;
    GetLocalTime(&st);
    char *today = new char[32];
    memset(today,' ', sizeof(today) );
    sprintf(today,"%d-%d-%d", st.wYear , st.wMonth , st.wDay);
    memset(buffer,'\0',sizeof(buffer));

    get_Website("api.ipify.org" );
    for (size_t i=0; i<website_HTML.length(); ++i) website_HTML[i]= tolower(website_HTML[i],local);

    token = strtok( buffer , seps );  
    while( token != NULL ){

      strcpy(lineBuffer[lineIndex],token);
      int dot=0;
      for (int ii=0; ii< strlen( lineBuffer[lineIndex] ); ii++ ){

          if (lineBuffer[lineIndex][ii] == '.') dot++;
          if (dot>=3){
              dot=0;
              strcpy(ip_address,lineBuffer[lineIndex]);
          }
      }

      token = strtok( NULL, seps );       
      lineIndex++;
   }
     cout<<"Your IP Address is  "<< ip_address<<" \n\n";

 return 0;
}


void get_Website(char *url ){
    WSADATA wsaData;
    SOCKET Socket;
    SOCKADDR_IN SockAddr;
    int lineCount=0;
    int rowCount=0;
    struct hostent *host;
    char *get_http= new char[256];

    memset(get_http,' ', sizeof(get_http) );
    strcpy(get_http,"GET / HTTP/1.1\r\nHost: ");
    strcat(get_http,url);
    strcat(get_http,"\r\nConnection: close\r\n\r\n");

    if (WSAStartup(MAKEWORD(2,2), &wsaData) != 0){
        cout << "WSAStartup failed.\n";
        system("pause");
        //return 1;
    }

    Socket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
    host = gethostbyname(url);

    SockAddr.sin_port=htons(80);
    SockAddr.sin_family=AF_INET;
    SockAddr.sin_addr.s_addr = *((unsigned long*)host->h_addr);

    if(connect(Socket,(SOCKADDR*)(&SockAddr),sizeof(SockAddr)) != 0){
        cout << "Could not connect";
        system("pause");
        //return 1;
    }
    send(Socket,get_http, strlen(get_http),0 );

    int nDataLength;
    while ((nDataLength = recv(Socket,buffer,10000,0)) > 0){        
        int i = 0;
        while (buffer[i] >= 32 || buffer[i] == '\n' || buffer[i] == '\r'){

            website_HTML+=buffer[i];
            i += 1;
        }               
    }

    closesocket(Socket);
    WSACleanup();
    delete[] get_http;
}
0

( Windows.)

, AF_INET6 , IPv4 IPv6 :

int ipv6only = 0;
setsockopt(hSock, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&ipv6only, sizeof(ipv6only));

accept:

char Sadr[max(sizeof(sockaddr_in), sizeof(sockaddr_in6))] = {0};
int ncbSzSadr = sizeof(Sadr);
if(getpeername(hSockAccept, (sockaddr*)Sadr, &ncbSzSadr) == 0)
{
    if(ncbSzSadr == sizeof(sockaddr_in))
    {
        //IPv4
        sockaddr_in* psadr_v4 = (sockaddr_in*)Sadr;

        print("Connected to client from %s, port %u...\n", 
            inet_ntoa(psadr_v4->sin_addr),
            (int)htons(psadr_v4->sin_port));
    }
    else if(ncbSzSadr == sizeof(sockaddr_in6))
    {
        //IPv6
        sockaddr_in6* psadr_v6 = (sockaddr_in6*)Sadr;

        WCHAR buff[256];
        PCTSTR p_strIpv6 = InetNtop(AF_INET6, psadr_v6->sin6_addr, buff, _countof(buff));

        _tprintf(L"Connected to client from %s, port %u...\n", 
            p_strIpv6,
            (int)htons(psadr_v6->sin6_port));
    }
    else
    {
        _tprintf(L"ERROR: getpeername bad size=%d\n", ncbSzSadr);
    }
}
else
{
    _tprintf(L"ERROR: (%d) getpeername\n", WSAGetLastError());
}

, ( , .)

, , , , , getpeername getsockname.

0

Source: https://habr.com/ru/post/1776999/

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