INFERNOUX
Member
Over the course of the last several hours I've spent some time messing around with the concept of UDP holepunching. I've put together a small "master server" on my local machine that is port forwarded, and have made two clients that are on two other networks out of state. As it stands, they're all using a command line system that I've put together to just handle connecting and disconnecting. Everything is working for network connection to the server, opening sockets and ports and communicating back and forth from both clients to my location.
After i've seen that both clients are connected I attempted to set up a small holepunching script, where the server sends both clients the opposing clients IP and Port, both clients send eachother packets multiple times, a random period of time apart.
Initially setting up the socket on the client in the create event:
Getting the IP and port from the server in the async networking event:
Sending the actual punch packets to each client in the step event:
As you can see, im sending multiple different packet and socket combinations between the clients. In order from top to bottom the combinations are:
1. the socket used to talk to the server, and the port that is used in initializing each client,
2. the socket used to talk to the server, and the port that the server is using,
3. a new socket the client created to emulate the servers socket (to try to spoof the firewall), and the port that is used in initializing each client,
4. as number 3, but communicating through the port that the server is using
5. the socket used to talk to the server, and the actual port that the server sees from the opposing client.
6. the new socket mentioned in number 3, and the actual port that the server sees from the opposing client.
now, the strange part that ive noticed through all of this testing (and the reason for number 5 and 6), is that the outgoing port, and the incoming ports don't match. Somewhere between GMS sending out the packets, and the packets getting received by the opposing clients, the port is changing.
The left set of ports is what one of the machines firewalls is seeing as the senders information. the right set is the listed destination on the machine. as you can see; the listed "sender" ports do not match any of the information that I had previously set up at all. I imagine this is either a feature in GMS, or a feature in Windows to try to make security better, but for holepunching to work I need to be able to force outbound sockets to actually be through the sockets im listing in the code. However, literally none of them match up 1:1. If anyone could give me any information on what may be causing that it would be extremely helpful, and if anyone could give me any potential solutions to the problem it would really help make the last few hours of troubleshooting "worth while" for me.
Thank you for everyone's time and patience.
After i've seen that both clients are connected I attempted to set up a small holepunching script, where the server sends both clients the opposing clients IP and Port, both clients send eachother packets multiple times, a random period of time apart.
Initially setting up the socket on the client in the create event:
GML:
network_set_config(network_config_use_non_blocking_socket,1);
mysocket = network_create_socket_ext(network_socket_udp,33115);Getting the IP and port from the server in the async networking event:
GML:
//begin holepunching
connection_ip = buffer_read(buffer,buffer_string);
connection_port = buffer_read(buffer,buffer_u32);
//send a message to the cmd to update the user
sendnotice("Attempting holepunching from " + myip + ":" + string(myport) + " to " + connection_ip + ":" + string(connection_port));
holepunch = 1; //variable for handling holepunching in the step event
var buff = buffer_create(256,buffer_grow,1);
buffer_write(buff,buffer_u16,2);
network_send_udp(mysocket,masterip,masterport,buff,buffer_get_size(buffer));
//send a notice to the master server that I am trying to holepunch
buffer_delete(buff);
GML:
if(holepunch){
if(punchtimer = maxtimer){ //room_speed/2 + irandom_range(0,25);
buff = buffer_create(256,buffer_grow,1);
buffer_write(buff,buffer_u16,4);
altsocket = network_create_socket_ext(network_socket_udp,35565);
network_send_udp(mysocket,connection_ip,33115,buff,buffer_get_size(buff));
network_send_udp(mysocket,connection_ip,35565,buff,buffer_get_size(buff));
network_send_udp(altsocket,connection_ip,33115,buff,buffer_get_size(buff));
network_send_udp(altsocket,connection_ip,35565,buff,buffer_get_size(buff));
network_send_udp(mysocket,connection_ip,connection_port,buff,buffer_get_size(buff));
network_send_udp(altsocket,connection_ip,connection_port,buff,buffer_get_size(buff));
buffer_delete(buff);
punchtimer = 0;
}
punchtimer++;
}As you can see, im sending multiple different packet and socket combinations between the clients. In order from top to bottom the combinations are:
1. the socket used to talk to the server, and the port that is used in initializing each client,
2. the socket used to talk to the server, and the port that the server is using,
3. a new socket the client created to emulate the servers socket (to try to spoof the firewall), and the port that is used in initializing each client,
4. as number 3, but communicating through the port that the server is using
5. the socket used to talk to the server, and the actual port that the server sees from the opposing client.
6. the new socket mentioned in number 3, and the actual port that the server sees from the opposing client.
now, the strange part that ive noticed through all of this testing (and the reason for number 5 and 6), is that the outgoing port, and the incoming ports don't match. Somewhere between GMS sending out the packets, and the packets getting received by the opposing clients, the port is changing.
The left set of ports is what one of the machines firewalls is seeing as the senders information. the right set is the listed destination on the machine. as you can see; the listed "sender" ports do not match any of the information that I had previously set up at all. I imagine this is either a feature in GMS, or a feature in Windows to try to make security better, but for holepunching to work I need to be able to force outbound sockets to actually be through the sockets im listing in the code. However, literally none of them match up 1:1. If anyone could give me any information on what may be causing that it would be extremely helpful, and if anyone could give me any potential solutions to the problem it would really help make the last few hours of troubleshooting "worth while" for me.
Thank you for everyone's time and patience.
Last edited:
