Please i really need help with tcp server

[pwarrow88]

Hi i need a little help writing a python program for a tcp server that allowed multiple client to connect and if one client sends a message to the server it will route that message to all connected clients also i can't figure out if there is a way to open lots of ports so that i wont be stuck only using one port if it possible can we open all ports i do not know programing so i have been at this issue for like weeks now Thank you anyone in advance that can help me you all are my only last hope at getting this project done.

[WereCatf]

20 minutes ago, pwarrow88 said:

if there is a way to open lots of ports so that i wont be stuck only using one port

Why would you want to do that?

[brentdahamster]

24 minutes ago, pwarrow88 said:

if there is a way to open lots of ports so that i wont be stuck only using one port if it possible

NOO Don't due that, that will make your internet more open to hackers or ddos attack.

[Master Disaster]

The answer you seek is called NAT.

 

26 minutes ago, pwarrow88 said:

...if it possible can we open all ports...

1) Not possible, some ports are hard reserved for vital services.

2) Even if you could you wouldn't want to. This is like smashing in your front door with a sledgehammer because you left your key at a mates house who only live 10 minutes down the road.

[WereCatf]

1 minute ago, Master Disaster said:

The answer you seek is called NAT.

I don't think OP is talking about port-forwarding here. The way I read it, OP wants their app, for some unfathomable reason, to listen on all the available ports on their system, which is both stupid and bad design. OP didn't say anything about opening ports on their router.

[Master Disaster]

6 minutes ago, WereCatf said:

I don't think OP is talking about port-forwarding here. The way I read it, OP wants their app, for some unfathomable reason, to listen on all the available ports on their system, which is both stupid and bad design. OP didn't say anything about opening ports on their router.

That's actually worse than what I thought

 

At that point your encroaching on rootkit/malware routines.

[WereCatf]

33 minutes ago, pwarrow88 said:

Hi i need a little help writing a python program for a tcp server that allowed multiple client to connect and if one client sends a message to the server it will route that message to all connected clients also i can't figure out if there is a way to open lots of ports so that i wont be stuck only using one port if it possible can we open all ports i do not know programing so i have been at this issue for like weeks now Thank you anyone in advance that can help me you all are my only last hope at getting this project done.

The typical way of handling multiple clients is:

1. The service is listening on a specific port for connections
2. Client connects to that port
3. The service asks the OS for a new, random port it can use and starts to listen on that port
4. The service replies to the client from that port and from there on out, the client and the service communicate over that port
5. If the client disconnects, the service closes that port

Repeat steps 2-5 for every client that connects.

[Guest]

First you need to research about sockets. 

 

Once you learn a bit about it you'll have more insight into what you really want to do. 

[Eigenvektor]

5 hours ago, WereCatf said:

The typical way of handling multiple clients is:

1. The service is listening on a specific port for connections
2. Client connects to that port
3. The service asks the OS for a new, random port it can use and starts to listen on that port
4. The service replies to the client from that port and from there on out, the client and the service communicate over that port
5. If the client disconnects, the service closes that port

Repeat steps 2-5 for every client that connects.

Communication also typically happens on a new thread, to be able to accept additional incoming connections while communicating with client #1 over that random port. At least if you want to be able to communicate with multiple clients concurrently.

 

After accepting a client connection, you spawn a new thread which then communicates with that client, while the main thread goes back to listening for new incoming connections. Not sure I found a good example, but here you go:

https://www.geeksforgeeks.org/socket-programming-multi-threading-python/

[Guest]

14 minutes ago, Eigenvektor said:

Communication also typically happens on a new thread, to be able to accept additional incoming connections while communicating with client #1 over that random port. At least if you want to be able to communicate with multiple clients concurrently.

 

After accepting a client connection, you spawn a new thread which then communicates with that client, while the main thread goes back to listening for new incoming connections. Not sure I found a good example, but here you go:

https://www.geeksforgeeks.org/socket-programming-multi-threading-python/

Depends how you do it. 

 

I typically run 2 threads. 

1 is basically a nothing thread/text input thread for the server so the program is never "not responding"

 

Then I have another thread that handles the network traffic and iterates through all the connections to see what is being said to the server. 

 

I never really thought to do it with a thread for each client. That's the beauty of programming though. Many ways to do the same task. 

[Eigenvektor]

9 minutes ago, fpo said:

I never really thought to do it with a thread for each client. That's the beauty of programming though. Many ways to do the same task. 

Sure, but depending on the number of concurrent clients and how long a connection can stay open you could run into timeouts if your server doesn't return to a listening state quickly enough. For example if I did this in Java:

ServerSocket serverSocket = new ServerSocket(portNumber);

while (serverIsRunning) {
    Socket clientSocket = serverSocket.accept();

    ... a download that takes 20 minutes
}

The server isn't going to return to the "accept" call until 20 minutes later meaning all other clients trying to connect to that port are going to run into TCP timeouts. Obviously if communication typically completes in (milli)seconds then this is not an issue.

[Guest]

3 hours ago, Eigenvektor said:

Sure, but depending on the number of concurrent clients and how long a connection can stay open you could run into timeouts if your server doesn't return to a listening state quickly enough. For example if I did this in Java:

ServerSocket serverSocket = new ServerSocket(portNumber);

while (serverIsRunning) {
    Socket clientSocket = serverSocket.accept();

    ... a download that takes 20 minutes
}

The server isn't going to return to the "accept" call until 20 minutes later meaning all other clients trying to connect to that port are going to run into TCP timeouts. Obviously if communication typically completes in (milli)seconds then this is not an issue.

Ahh yeah. I haven't done that yet.