[Release] Connect Server - Linux - Source - Proof of Concept

[Regz]

Hi Ragezone! I releasing my simple connect server source for Linux that you can use to hide first contact IP. Feel free to modify code.

connectserver.c:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <arpa/inet.h> 
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

u_char gameserver_addr[] = "192.168.1.168";
int gameserver_port = 56900;

int server_port = 44405;
int max_clients = 30;
int server_count = 1;

u_char packet_welcome[] = { 0xC1, 0x04, 0x00, 0x01 };

void SetPacket(const uint8_t *source, size_t sourceOffset, uint8_t *result, size_t resultOffset, size_t length)
{
	memcpy(result + resultOffset, source + sourceOffset, length);
}

int main(int argc , char *argv[])
{
		int opt = 1;
		int _ms_ , _ns_, i , valread , sd, max_sd;
		int sockets[max_clients];

		for (i = 0; i < max_clients; i++){ sockets[i] = 0; }

		if( (_ms_ = socket(AF_INET , SOCK_STREAM , 0)) == 0)
		{
			perror("socket failed");
			exit(EXIT_FAILURE);
		}

		if( setsockopt(_ms_, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0 )
		{
			perror("setsockopt");
			exit(EXIT_FAILURE);
		}
		
		struct sockaddr_in address;
		address.sin_family = AF_INET;
		address.sin_addr.s_addr = INADDR_ANY;
		address.sin_port = htons( server_port );

		if (bind(_ms_, (struct sockaddr *)&address, sizeof(address))<0)
		{
			perror("bind failed");
			exit(EXIT_FAILURE);
		}
		printf("Listener on port %d \n", server_port);

		if (listen(_ms_, 3) < 0)
		{
			perror("listen");
			exit(EXIT_FAILURE);
		}

		int _as_ = sizeof(address);
		puts("Waiting for connections ...");

		fd_set readfds;
		
		while(1)
		{
				FD_ZERO(&readfds);

				FD_SET(_ms_, &readfds);
				max_sd = _ms_;

				for ( i = 0 ; i < max_clients ; i++)
				{
						sd = sockets[i];

						if(sd > 0)
								FD_SET( sd , &readfds);

						if(sd > max_sd)
								max_sd = sd;
				}

				int activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);

				if ((activity < 0) && (errno!=EINTR))
				{
						printf("select error");
				}

				if (FD_ISSET(_ms_, &readfds))
				{
						if ((_ns_ = accept(_ms_, (struct sockaddr *)&address, (socklen_t*)&_as_))<0)
						{
								perror("accept");
								exit(EXIT_FAILURE);
						}
						printf("New client , socket fd is %d , ip is : %s , port : %d \n" , _ns_ , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
						if( send(_ns_, packet_welcome, sizeof(packet_welcome), 0) != sizeof(packet_welcome) )
						{
								perror("send");
						}
						puts("Welcome message sent successfully");
						for (i = 0; i < max_clients; i++)
						{
								if( sockets[i] == 0 )
								{
										sockets[i] = _ns_;
										printf("Adding to list of sockets as %d\n" , i);

										break;
								}
						}
				}

				for (i = 0; i < max_clients; i++)
				{
					sd = sockets[i];
					if (FD_ISSET( sd , &readfds))
					{
						u_char buffer[1025];
						memset(buffer,0,strlen(buffer));
						if ((valread = read( sd , buffer, 1024)) == 0)
						{
								getpeername(sd , (struct sockaddr*)&address , (socklen_t*)&_as_);
								printf("Host disconnected , ip %s , port %d \n" , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
								close( sd );
								sockets[i] = 0;
						}
						else
						{
							switch ((u_char)buffer[0])
							{
								case 0xC1:
									switch ((u_char)buffer[2])
									{
										case 0xF4:
											switch ((u_char)buffer[3])
											{
												case 0x03:
												{
													int server_code = ((u_char)buffer[4] + (u_char)buffer[5] * 256);
													int server_index = (server_code / 20);
													int sub_index = (server_code % 20);
													u_char packet_info[] = { 0xC1, 0x16, 0xF4, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, (u_char)(gameserver_port & 0xFF), (u_char)(gameserver_port >> 8) };
													SetPacket(gameserver_addr, 0, packet_info, 4, sizeof(gameserver_addr));
													send(sd, packet_info, sizeof(packet_info), 0);
												}
												break;

												case 0x06:
												{
													u_char server_list[2000];
													int packet_size = 7 + (4 * server_count);
													u_char packet_list[] = { 0xC2, (u_char)(packet_size >> 8), (u_char)(packet_size & 0xFF), 0xF4, 0x06, (u_char)(server_count << 8), (u_char)(server_count & 0xFF) };
													SetPacket(packet_list, 0, server_list, 0, 7);
													
													int temp = 7;
													for (int i = 0; i < 21; i++)
													{
														for (int z = 0; z < 20; z++)
														{
															server_list[temp++] = (u_char)((i * 20 + z) & 0xFF );
															server_list[temp++] = (u_char)((i * 20 + z) >> 8);
															server_list[temp++] = 0;
															server_list[temp++] = 0;
														}
													}
													send(sd, server_list, sizeof(server_list), 0);
												}
												break;
											}
											break;
									}
									break;
								}
							}
						}
				}
		}

		return 0;
}

How to compile?

Debian:

apt-get install gcc

gcc connectserver.c -o connectserver

and run

./connectserver

What will be next? Maybe simple linux gameserver or something.