Python socket bind to any IP?

Question

I have a small one sided message sender that works while I specify the IP to connect to in code, however, I am having trouble allowing the socket to accept connections from any IP. Here is the line that is the problem.

mySocket = socket.socket ( socket.AF_INET, socket.SOCK_STREAM )
mySocket.bind ( ( '', 2727 ) )

The '' is for localhost, and it works if I manually enter IP, eg '192.168.1.106', however, how can I leave it open to all? Or am I using the wrong connection type for this?

Answer 1

If you want to bind to all available IPv4 addresses, specify 0.0.0.0 as your IP address. If you're behind a router and wish to have your socket internet-accessible, rather than just available on your LAN, you'll need to set up a port forwarding rule so that users outside your LAN can access the service.

See the following ServerFault question for more info on 0.0.0.0: https://serverfault.com/questions/78048/whats-the-difference-between-ip-address-0-0-0-0-and-127-0-0-1

• CMCDragonkai: Is it possible to bind to completely custom ips like 152.64.87.9?
• Polynomial: @CMCDragonkai Only if your system has an interface with that address.
• CMCDragonkai: So I would need to create these interfaces prior to binding to them. And creating virtual interfaces would be loopbacks right?
• Craig McQueen: Would that be IPv4 only? What about binding on all available IPv6 addresses?

Answer 2

Binding to '' has the same effect as to '0.0.0.0' makes the transition to IPv6 easier.

Depending on the OS, opening a socket.AF_INET6 socket listens to IPv4 and IPv6.

• johnthagen: Python bug report to make the docs more explicit about this: bugs.python.org/issue33921
• johnthagen: According to the docs, '' is not compatible with IPv6: This behavior is not compatible with IPv6, therefore, you may want to avoid these if you intend to support IPv6 with your Python programs.

Answer 3

Binding to 0.0.0.0 will allow it to accept connections from any IPv4 address that can route to it.