Book Image

Mastering Python Networking

By : Eric Chou
Book Image

Mastering Python Networking

By: Eric Chou

Overview of this book

This book begins with a review of the TCP/ IP protocol suite and a refresher of the core elements of the Python language. Next, you will start using Python and supported libraries to automate network tasks from the current major network vendors. We will look at automating traditional network devices based on the command-line interface, as well as newer devices with API support, with hands-on labs. We will then learn the concepts and practical use cases of the Ansible framework in order to achieve your network goals. We will then move on to using Python for DevOps, starting with using open source tools to test, secure, and analyze your network. Then, we will focus on network monitoring and visualization. We will learn how to retrieve network information using a polling mechanism, ?ow-based monitoring, and visualizing the data programmatically. Next, we will learn how to use the Python framework to build your own customized network web services. In the last module, you will use Python for SDN, where you will use a Python-based controller with OpenFlow in a hands-on lab to learn its concepts and applications. We will compare and contrast OpenFlow, OpenStack, OpenDaylight, and NFV. Finally, you will use everything you’ve learned in the book to construct a migration plan to go from a legacy to a scalable SDN-based network.
Table of Contents (22 chapters)
Humble Bundle
About the Author
About the Reviewer
Customer Feedback
OpenStack, OpenDaylight, and NFV

Packet inspection

In this section, we will take a closer look at the PacketIn message and parse the packet so we can further process the event and determine the corresponding action. In, we can use the ryu.lib.packet.packet method to decode the packet:

from ryu.lib.packet import packet
import array
@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def _packet_in_handler(self, ev):
    print(" {}".format(array.array('B',
    pkt = packet.Packet(
    for p in pkt.protocols:
        print(p.protocol_name, p)

Note that is in bytearray format, which is why use the array.array() function to print it out. We can then initiate a ping, h1 ping -c 2 h2, and observe in the output the arp from h1 to h2:

EVENT ofp_event->SimpleSwitch13 EventOFPPacketIn array('B', [255, 255, 255, 255, 255, 255, 0, 0, 0, 0, 0, 1, 8, 6, 0, 1, 8, 0, 6, 4, 0, 1, 0, 0, 0, 0, 0, 1, 10, 0, 0, 1, 0, 0, 0, 0, 0, 0, 10, 0, 0, 2])