As a learning excercise I wrote this Flask app utilizing the awesome netaddr Python library. Designed as subnetting tool for network engineers.
CIDR Tools is an app to assist in network address planning/design. I wanted to learn the basics of writing a python-based web application and at the same time have a simple tool to use. This application has the following functions:
- Disector - this takes any IPv4 address in CIDR form and shows details about it
- Subnet - is used to break up a parent network into subnets based on a new desired prefix length
- Supernet - is to show what parent networks a subnet belongs to
- Summary - given a list of hosts and/or networks, produce the summary prefix(s)
- Splitnet (in progress) - show the prefix summaries after splitting up a prefix
The results are provided in an HTML table, so data is easily cut/paste into a spreadsheet or other forms of documentation.
Create forms to generate complex IP address design schemas base on a design template. For example, a design template could represent a branch office, floors in a building or large campus. The addressing schemas could then be imported into an IPAM solution such as Netbox or Infoblox.
Make sure your system is already setup with Python 3.12, pip and git
Clone the repo (it will create a application folder called "cidrtools")
git clone https://github.com/ja3600/ipv4cidrtools.git
Change into the directory:
cd ipv4cidrtools
Create a virtual environment, activate and use Pip to install required Python packages:
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
Run it!
flask run
Point your local browser to http://127.0.0.1:5000
Be sure to install podman on your macOS machine.
Change directory into the project folder where the Containerfile lives.
cd ipv4cidrtools
podman build -t cidr-app .
podman run -p 5001:5000 cidr-app
Open browser to http://127.0.0.1:5001
Remove one or more containers podman rm -a
Removes one or more previously pulled or locally created images. podman rmi -a
podman images
REPOSITORY TAG IMAGE ID CREATED SIZE localhost/cidr-app latest 9b1224c4a888 8 minutes ago 205 MB docker.io/library/python 3.13-slim f13bda0a127e 2 weeks ago 147 MB
Used this great tutorial: https://blog.entirely.digital/docker-gunicorn-and-flask/
Assumptions: Your system is already setup and running Docker version 13.1 or higher
First, clone the repo (it will create a application folder called "cidrtools")
git clone https://github.com/ja3600/cidrtools.git
Change into the directory:
cd cidrtools
Build the container (this uses the Dockerfile):
docker build --tag flask_cidrtools .
Run it (first time) detached, as a daemon
docker run --name cidrtools -d -p 5000:5000 flask_cidrtools
Run it (first time) to see debug errors..
docker run --name cidrtools -p 5000:5000 flask_cidrtools
Stop or start it:
docker stop cidrtools
docker start cidrtools
Other useful Docker commands:
docker ps -a
docker images -a
docker system prune
Login into the container (by running bash):
docker exec -u root -t -i cidrtools /bin/bash
Copy files to a container:
docker cp src_filename.txt cidrtools:/dst_filename.txt
Delete all containers and images:
docker ps -a -q | xargs docker rm
docker images -a -q | xargs docker rmi -f
These instructions are based on CentOS Linux release 7.7 These steps assume your system already has python3 and pip installed This is handy if you are developing/testing new code
Install virtual environment:
pip install virtualenv --user
Create a new environment for Flask:
virtualenv flask-env
Activate the new environment:
source flask-env/bin/activate
Clone the cidr-tools files from Github:
https://github.com/ja3600/ipv4cidrtools.git
This will create a new directory called cidrtools.
Move into this new directory
cd cidrtools
Now install Flask and other dependencies:
pip install -r requirements
Allow port TCP 5000 through the Linux firewall, if required:
firewall-cmd --permanent --zone=public --add-port=5000/tcp
firewall-cmd --reload
Run the application...
python3 app/app.py
To enable the Flask environment automatically when you log in:
Add this line to the end of your .bashrc
cd ~
source ~/flask-env/bin/activate