sorry for the noobish question but I can't find any resources online clearly stating whether this should work or not, and all tutorials / sample code always use localhost ^^ Soooo...
I'm trying to setup a simple server / client using RakNet. I'm literally just following the first tutorial (http://www.jenkinssoftware.com/raknet/manual/tutorial.html), just trying to get the client to connect to the server and keep the connection alive for a bit.
It all works great as long as I use 127.0.0.1 or 192.168.0.XXX, I can start the server, then the client, the server detects the connection request and sends the reply to the client, the client receives the reply and prints out "connection accepted" and such, and I can exchange messages between the client and the server.
However if I try using my actual IP, the server does not seem to detect the connection request (if you look at the tutorial code, it doesn't print "incoming connection"), but the client still receives a reply from somewhere ("Our connection request has been accepted").
After this initial semi-successful connection, no more packets will be received by either server or client, and the client will inevitably get disconnected after a few seconds (I assume time out?).
Port is open on the router, and the app runs fine as long as I keep it on localhost.
So my question is: is it even possible to run a server and client on the same machine / IP which is sitting behind a router?
The RakNet documentation part about NAT punchthrough and UDP forwarding does mention no more than one client and server being able to run on the same machine, but I was under the impression that one server / one client would not be an issue?
Thanks in advance to anybody who can shed some light on this!!
Forgot to mention my firewall is disabled !
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Writing a UDP client-server app in C++ (done that lots of times before in many languages in the past 15 years), but somehow this one is not working correctly.
I cannot post actual code nor minimal reproducible app at the moment but I am willing to pay for live help if anyone is available to help solve this quickly with screensharing.
I think this is a particularity with C++ sockets and the way I am using them in this specific app which is quite complex.
Basically the issue is that the packets sent from the server to the client are not received by the client, only when said client is on a separate nat.
When both in same local networking and using their local IP, everything works as expected.
Here is what I am doing :
Client sendto(...) packets through UDP to the server using a specific server host and port 12345 (and keeps sending these non-stop)
On another thread, client bind(...) on port 12345 and "0.0.0.0" and tries to poll() and recvfrom() in a loop (poll always returns 0 here when client is on a separate nat)
Server bind() on port 12345 and "0.0.0.0" then poll() and recvfrom() in a loop
Upon receiving the first UDP message from a client, it starts a thread for sending
UDP messages back to the client on a new socket, using the
sockaddr_in that it got from the recvfrom() to pass in the sendto() commands.
Result : Server perfectly receives ALL messages from all clients, and sends all messages back to all clients, but any client that is not on the same NAT will never receive any messages (poll() always returns 0).
As far as I understand it, when the client sends a UDP message to the server on a specific remote port (12345 in this case), it will punch a hole in its NAT so that it can receive messages back from the remote server on that port...
I tested five different client network configurations :
Local network with the server, using local IP addresses (WORKS)
Local network with the server while client is using a VPN thus going through a remote NAT (DOES NOT WORK)
Local network with the server but client is using the WAN ip address to connect to the server (DOES NOT WORK)
Client at an actual remote network from a friend's connection, behind a router (DOES NOT WORK)
Client going through a wifi hotspot created using my phone (DOES NOT WORK)
For all tests above, the server was correctly receiving all communications from clients.
I also tried forcing the port to 12345 for the sendto() instead of using the sockaddr_in as set from recvfrom(), same issue.
Am I doing anything wrong ?
If you want to help but need to see actual code, I can do that live with screen sharing and I will pay for the help.
Thanks.
Also, if anyone can point me to a great site where I can pay for VERY QUICK help, please let me know, I don't even bother searching google because I really want actual advice from people who tried these services, not ads trying to rip me off...
Only the original receiver socket is allowed to reply to the client, because it's the client request that opens the port in the NAT. So either use the same socket in the server to receive and reply, or get the port that the second server socket was bound to and transfer it with an initial message through the original server port, so that A can send to it and punch the hole.
It looks so strange to create two half duplex sockets when a socket is a full duplex communication object that I'd go with the first option.
I have created simple TCP server which accepts connections and request and do some processing. I have referred following example and it is working fine. I send data to to connected client continuously and it is being printed on client side. Though after around period of 20-25 minutes, the client stops receiving any data. Also after such incident, the server shows running but now when I connect my client again to server, the server's connection accept handler doesnt get invoked. But I am able to telnet to the server's port and client is able to connect. Any idea what might be the problem?
I coded a server/client application which i ran first locally and then over the internet. Therefore i configured my router that it accepts data on port xxxx and forward it to my machine where my server runs and where it accepts connections from client sockets. So everything runs fine and the clients can send there messages to each other. So now my question is, how is it possible that the server can send data to the clients in other networks where port forwarding isn´t activated but when i try it manually it doesn´t work.
I already tried searching about how the TCP saves IPs and ports and I also looked up how the concept of the Internet/TCP/UDP works but couldn´t find an answer to the question.
So first of all I wanted to know that before I implement my server without port forwarding and it would also be appreciated if you could give code examples for c++ on windows if you have any ideas so that i can establish such connections without port forwarding and extern serverhosts on the internet.
Clint -> NAT (router) -> ... -> NAT (router) -> server
When client sends a message (it can be a connection attempt in case of TCP or just a message if it's UDP), its NAT doesn't block it and remembers which local address:port it's coming from and to which address:port it's going to: [client address:port, server address:port]. When the message hits server's NAT, the NAT knows about your server because you configured "port forwarding" and passes the message to local network. Now, when server sends message back to client and it reaches client's NAT, the NAT checks its internal table, finds a record for this particular server address:port, retrieves client address:port part and passes the message to it. So everything works as expected.
It's why usually when you open your browser and go to some web link, you receive server response with web page without problems despite you are behind NAT.
It's a simplified explanation which omits local/global address:port details.
I've got server running in background and a program which should display data from server. I want to somehow launch method in my program from server. So server should be a sender, but how to do it ?
There is no reason why a server can't also be a client, just implement the interfaces from both sides and you're good.
The main thing to worry about is deadlocking: if you have a single threaded program which is waiting for the reply of the server, then it will not handle the request that the server sends, so the server is stuck and will not send a reply to the program.
This can be solved by starting the server implementations on different threads and letting them not block on the client thread.
Even better is to avoid having a server send back requests before sending replies, but cascading requests (forward requests to more specialized servers) should be no problem.
I have client server application that works with Firebird server. Everytime when clients connect to the server they(client apps) don't check if there is a network connection to the server so at this time my application sometimes freezes when the server computer is switched off or service has stopped, so first of all I need to check connection if remote host is switched on or at some port anything listening....
Before establishing the connection I need to check it and make sure server and service is running using Indy components.
Any ideas? also I can use IcmpClient to ping remote host and then establish connection but which is the most optimal way ?
If you just want to check if the server computer can be reached, you could do a "ping" to check that. However, if you want to check if a specific TCP port is open, then the only way to find that out is to actually do a proper connect, which leads to the "freezing" program while the connection times out if there is no-one listening on that port.