How to bind both IPv4 and IPv6 source address to Python socket?

Question

I wish to create a TCP server using sockets, that binds to both IPv4 and IPv6 addresses.

Is there a way to do it without creating 2 sockets?

Answer 1

The feature you're looking for is called "dual-stack", or an IPv4 + IPv6 dual-stack socket.

Since Python 3.8, you're able to easily do so using socket.create_server().

Setting the parameter dualstack_ipv6=True will allow you, on supported systems, to listen on both IPv4 and IPv6 addresses using the same socket.

If you wish to check if your system supports dual-stack sockets, use socket.has_dualstack_ipv6().

Code example from the Python docs:

import socket

addr = ("", 8080)  # all interfaces, port 8080
if socket.has_dualstack_ipv6():
    s = socket.create_server(addr, family=socket.AF_INET6, dualstack_ipv6=True)
else:
    s = socket.create_server(addr)