Validating input is always important - you don’t want random errors popping up when you try to directly insert user-inputted data into your functions.

Python has lots of built-in validation. For example, if you’re expecting a number, you can do something like this:

    try:
        intVariable = int(stringVariable)
    except ValueError:
        print "That was not a number. Try again"

It’s very straightforward to validate built-in types in Python, but an IP address is just a string in Python - and any string is a valid string.

We need a way to ensure that it’s a valid IP address. Here’s how:

import socket

try:
    socket.inet_aton(stringVariable)
except socket.error:
    print "That was not a valid IP address"

This is the Python 2 version of how to do it. Apparently Python 2 is deprecated or something because we have this fancy new Python 3, which, incidentally, has a built-in IP address type.

You can do the same thing in Python 3 like this:

import ipaddress

try:
    myIpAddress = IPv4Address(stringVariable)
except ValueError:
    print "That was not a valid IP address"

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