How to let client application outside your netowrk connect to your server - sockets

Question

I'm new to socket programming. I have developed fundamental/simple client and server application where client successfully communicates with server. Currently, both the server is on my system (local host) and client is also my system.
Now I want to somehow allow clients outside the network ( network where my system belongs to) to communicate with the server but i have no idea what to do and how to proceed. Any help would be appreciated.
Here's a smaple code taken from here
server.py
enter code here
import socket
# next create a socket object
s = socket.socket()
print "Socket successfully created"
port = 12345
s.bind(('', port))
print "socket binded to %s" %(port)
s.listen(5)
print "socket is listening"
while True:
# Establish connection with client.
c, addr = s.accept()
print 'Got connection from', addr
c.send('Thank you for connecting')
c.close()
client.py
import socket
s = socket.socket()
port = 12345
s.connect(('127.0.0.1', port))
print s.recv(1024)
s.close()

Answer 1

You don’t really need to change anything in your code, except for the IP that the client connects to. It needs to be the server PC’s public Internet IP instead of 127.0.0.1.
If the server PC is connected directly to the Internet modem, then you are done.
Otherwise, if the server PC is behind a router or proxy, then you need to configure port forwarding on that router/proxy to forward traffic from its public WAN IP/port to the server PC’s LAN IP/port. Consult your router/proxy’s documentation for how to do that configuration.
If the router/proxy has uPNP enabled, your server code can dynamically forward the WAN IP/port to itself at runtime. See Python: Open a Listening Port Behind a Router (upnp?)