If you need to know the IP address of a remote machine, you can use a built-in library function, gethostbyname(). In this case, you need to pass the remote hostname as its parameter.

In this case, we need to call the gethostbyname() class function. Let's have a look inside this short code snippet.

Listing 1.2 shows how to get a remote machine's IP address as follows:

#!/usr/bin/env python
# Python Network Programming Cookbook -- Chapter – 1
# This program is optimized for Python 2.7.
# It may run on any other version with/without modifications.

import socket

def get_remote_machine_info():
    remote_host = 'www.python.org'
    try:
        print "IP address: %s" %socket.gethostbyname(remote_host)
    except socket.error, err_msg:
        print "%s: %s" %(remote_host, err_msg)
    
if __name__ == '__main__':
    get_remote_machine_info()

If you run the preceding code it gives the following output:

$ python 1_2_remote_machine_info.py 
IP address of www.python.org: 82.94.164.162

This recipe wraps the gethostbyname() method inside a user-defined function called get_remote_machine_info(). In this recipe, we introduced the notion of exception handling. As you can see, we wrapped the main function call inside a try-except block. This means that if some error occurs during the execution of this function, this error will be dealt with by this try-except block.

For example, let's change the remote_host value and replace www.python.org with something non-existent, for example, www.pytgo.org. Now run the following command:

$ python 1_2_remote_machine_info.py 
www.pytgo.org: [Errno -5] No address associated with hostname

The try-except block catches the error and shows the user an error message that there is no IP address associated with the hostname, www.pytgo.org.