Home/ Questions/Q 1094757
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-17T00:01:04+00:00

In ASIO, s it possible to create another socket that has the same source

  • 0

In ASIO, s it possible to create another socket that has the same source port as another socket?

My UDP server application is calling receive_from using port 3000. It passes the packet
off to a worker thread which will send the response (currently using a dynamic source port).

The socket in the other thread is created like this:

udp::socket sock2(io_service, udp::endpoint(udp::v4(), 0));

And responds to the original request using the sender_endpoint saved with the original packet.

What I’d like to be able to do is respond to the client using the same source port as the server is listening on. But I can’t see how that can be done. I get an exception if I try that saying address in use. Is it possible to do what I’m asking? The reason I want that is if I use dynamic ports, it means the clients need to add special firewall rules in windows to allow the reply packets to be read. I’ve found that if the source port is the same in the reply, windows firewall will allow it to pass back in.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You should be able to use the SO_REUSEADDR socket option to bind multiple sockets to the same address. But having said that, you don’t want to do this because it’s not specified which socket will receive incoming data on that port (you would have to check all sockets for incoming data)

    The better option is just to use the same socket to send replies – this can safely be done from multiple threads without any additional synchronisation (as you are using UDP).

    • 0