Python for Network Engineers

Abstract Classes in Python

By George El. • August 2020 • Reading time: 2 minutes

In my post Classes in Python I have an example of creating a class named Car and instantiating this class. In reality you would rarely do something like this, but rather use this class as a base class in order to create subclasses. Subclasses are classes that extend the base class and inherit all functionality from it.

Create a Tkinter Gui With Sqlite Backend

By George El. • March 2020 • Reading time: 4 minutes

In this post I will show you how to create a single gui app using tkinter as frontend and sqlite as a backend. Python has many gui libraries and tkinter is one of them that is supported natively, that is you don’t need to install any extra modules. The app has the ability to search, add, update and delete router from a sqlite database.

Perform an Arp Poisoning Attack Using Scapy

By George El. • November 2019 • Reading time: 3 minutes

In this post I will show you how to perform an arp poisoning attack on local network using a python package called scapy. Scapy is a package that allows us to craft our own packets specifying all layers from layer2 to layer7. In my local network I have two pcs, with addresses 192.

How to Talk to Mysql Databases

By George El. • August 2019 • Reading time: 7 minutes

In this post I will describe how to use python to execute raw queries on mysql databases. install the database First we need to install mysql or maria-db (a fork of mysql) either in unix or windows. if you have windows 10 you can install mysql on wsl (windows subsystem for linux).

Using TextFSM to Parse Cli Output

By George El. • July 2019 • Reading time: 4 minutes

Many times we connect to a router or switch usually with netmiko and we want to parse the output of a command. TextFSM is a Python module for parsing semi-structured text into python tables. It uses templates that use regular expressions in order to parse the output. The good thing is that there are already hundreds of templates for many devices and commands.

Using CiscoConfParse to Parse Cisco Configurations

By George El. • June 2019 • Reading time: 3 minutes

In this post I will present a python module that makes the parsing of cisco configuration files easy. The module is called CiscoConfParse Lets start by installing it pip install ciscoconfparse I will use the following cisco file which is taken from the documentation site, but I have added a few lines in the beginning

Sort Html Links in One Line

By George El. • May 2019 • Reading time: 2 minutes

Recently I had to sort a lot of html links in a program I created, so I decided to write a simple one line script to do it in python. The html links are in file called links.txt The file looks like this: <a href="file1">a</a> <a href="file2">c</a> <a href="file3">z</a> <a href="file4">b</a> <a href="file5">x</a> <a href="file6">e</a> <a href="file7">f</a> <a href="file8">g</a> <a href="file9">y</a> the code I came up with is:

Null Object Pattern

By George El. • April 2019 • Reading time: 2 minutes

In this post I will explain a pattern used in OOP, called Null Object Pattern. This pattern allows us to use our code as usual even if what we get back is a null object. Lets first see an example without using the pattern. I will create a dictionary called Persons that will hold Person objects.

How to Use SQLalchemy to Talk to SQL Databases

By George El. • April 2019 • Reading time: 4 minutes

In this post I will describe briefly sqlalchemy. SqlAlchemy is a package that allows the user to talk to sql databases. Except for performing raw sql queries, it provides an Object Relational Mapper, ORM. An ORM maps classes to tables in the database, and objects to table rows. So instead of running sql queries on the tables, you perform actions on the objects, and the ORM takes care of translating these actions to sql queries.

Simple Factory Pattern

By George El. • April 2019 • Reading time: 2 minutes

In this post I will continue from my post Abstract Classes in Python and do some modifications in order to make my design more efficient and extensible. First of all I will create a folder named carclasses and create an file that will contain the following: from .vwcar import VWCar from .