Install python scapy on MAC OS X Sierra

Python ships by default with OSX and resides in the path /usr/bin/python. Having run into a lot of problems with installing and using scapy and other packages with the correct version of python, pip and homebrew, I decided to write steps that anyone can follow to setup a clean and working python environment in OSX without running it in a virtual environment.

Step 0: Check existing python version by the command `which python`. This should yield
$ /usr/bin/python

Step 1: Install homebrew
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
(Reference: https://brew.sh/)

Step 2: Install python and pip using brew and pypcap using pip:
brew install python
pip install pypcap

Step 3: Setup your PATH variable correctly in ~/.bashrc to use the python installed by the above command in /usr/local/bin:
PATH=/usr/local:/usr/local/bin:$PATH
(add the above line at the end of your ~/.bashrc or ~/.zshrc, whichever shell you are using)

Step 4: Force updates to PATH variable by using source:
$ source ~/.bashrc

Step 5: At this point, if everything worked correctly, the output of `which python` and `which pip`should yield /usr/local/bin/python and /usr/local/bin/pip respectively

Step 6: Install scapy
$ pip install scapy

Step 7: Run scapy
If you get errors like "INFO: Can't import packageXYZ. ...", see step 8 below to fix dependencies.

Step 8: Fix Dependencies
i) pyx
(If using python 2.7): $ pip install pyx==0.12.1 -I --no-cache
(If using python 3): $ pip install pyx

ii) pycrypto
$ pip install pycrypto

iii) ecdsa lib
$ pip install ecdsa

Step 9: Test scapy again
19:55:35 Karans-MacBook-Pro ~: scapy
Welcome to Scapy (2.3.3)
>>>

The above shows a successful run of scapy with all dependencies correctly installed.