Srivastava - Python Network Programming: Use Python 3.7 To Get Network Applications Up and Running Quickly and Easily

Python Network Programming
step by step

Use Python 3.7 To Get Network Applications Up and Running Quickly and Easily
SACHIN Srivastava
Python Network Programming

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About the Author

Sachin Srivastava is a software architect, where he is responsible for the development of tools to make it easier to create and manage cloud computing resources. Previously, as a principal engineer at Harman Connected Services, he was the co-inventor and lead developer of a web-based document management product from Harman. He is the creator of boto, an open source Python library for cloud computing, where he has been shaping various Linux and open source software solutions, mainly on cloud computing platforms, for commercial companies, educational institutions, and multinational consultancies.

Over the past 10 years, he has been leading a number of Python software development and cloud infrastructure automation projects. He takes an active interest in cloud computing, software security, intelligent systems, and childcentric education. He lives in India.

All praises and thanks to Hanuman Ji, the God who is the Merciful and the Beneficent. I would not be able to finish this book without the help of God. I would like to thank Publishers entire team for being were very friendly and cooperative in this long journey. I would also like to thank my family and friends for their sacrifice of time, encouraging words, and smiles.

About the Reviewer

Vikash Singh is a technical support professional, who has more than 15 years of experience in a wide range of operating systems, database services, scripting, networking, and security in the mobile telecommunication systems. He actively participates in the adaption of various vendor equipment projects to live mobile operator networks.

He has worked on the following technologies:

Mobile systems such as GSM, UMTS, 3G, and WiFi
Vendors such as Cisco, ALU, NSN, RedHat, and Canonical
Network elements such as MSC, VLR, HLR, MSCS, OCS, NGIN, and PCRF
Network protocol suites such as SS#7 and TCP/IP
Webpage technologies such as HTTP, XML, HTML, SOAP, and REST
Operating systems such as Linux (Debian, Ubuntu, RHEL, and CentOS), Windows, and Unix

Virtualisation and Cloud technologies such as EC2, OpenStack, VMware, VirtualBox, and so on

Programming languages such as Perl, Python, awk, bash, C, Delphi, Java, and so on
Databases such as MongoDB, InfluxDB, MySQL, MS SQL, Oracle, and so on

Monitoring systems such as Nagios, Grafana, Zabbix, and so on

Table of Contents

Preface vii

Firewalls 24

Summary 28

Handling problems 33

Customizing requests 36
Content negotiation 40
Content types 40

Cookies 43
Cookie handling 44
Know your cookies 45
Redirects 47
URLs 48
Paths and relative URLs 49
Query strings 51
URL encoding 52
URLs in summary 54
HTTP methods 55
The HEAD method 55
The POST method 55
Formal inspection 56
HTTPS 58
The Requests library 59
Handling errors with Requests 63
Summary 64
Chapter 3: APIs in Action 65
Getting started with XML 66
The XML APIs 66
The basics of ElementTree 67

Pretty printing 68
Element attributes 69
Converting to text 70
The Amazon S3 API 70
Registering with AWS 71
Authentication 71
Setting up an AWS user 72

Regions 73
S3 buckets and objects 74
An S3 command-line client 74
Creating a bucket with the API 76
Uploading a file 78
Retrieving an uploaded file through a web browser 79
Displaying an uploaded file in a web browser 80
Downloading a file with the API 81
Parsing XML and handling errors 82
Parsing XML 82
Finding elements 83
Handling errors 84
Further enhancements 84
The Boto package 85
Wrapping up with S3 87
JSON 87
Encoding and decoding 88
Using dicts with JSON 88
Other object types 89
The Twitter API 90
A Twitter world clock 91
Authentication for Twitter 91
Registering your application for the Twitter API 91
Authenticating requests 92
A Twitter client 92
Polling for Tweets 94
Processing the Tweets 95
Rate limits 96
Sending a reply 97
Final touches 98
Taking it further 99
Polling and the Twitter streaming APIs 99
Alternative oAuth flows 99
HTML and screen scraping 100
HTML parsers 101
Show me the data 102
Parsing HTML with lxml 102
Zeroing in 103
Searching with XPath 104
XPath conditions 105
Pulling it together 106
With great power... 107
Choosing a User Agent 108
The Robots.txt file 108
Summary 109
Chapter 4: Engaging with E-mails 111
E-mail terminologies 111
Sending e-mails with SMTP 112
Composing an e-mail message 113
Sending an e-mail message 114
Sending e-mails securely with TLS 117
Retrieving e-mails by using POP3 with poplib 121
Retrieving e-mails by using IMAP with imaplib 123
Sending e-mail attachments 126
Sending e-mails via the logging module 128
Summary 131
Chapter 5: Interacting with Remote Systems 133
Secure shell access using Python 134
Inspecting the SSH packets 137
Transferring files through SFTP 139
Transferring files with FTP 140
Inspecting FTP packets 142
Fetching Simple Network Management Protocol data 143
Inspecting SNMP packets 146
Reading Light-weight Directory Access Protocol data 147
Inspecting LDAP packets 151
Sharing files with SAMBA 153
Inspecting SAMBA packets 156
Summary 158
Chapter 6: IP and DNS 159
Retrieving the network configuration of a local machine 159
Manipulating IP addresses 161
IP network objects 162
Network interface objects 163
The IP address objects 164
Planning IP addresses for your local area network 165
GeoIP look-ups 167
DNS look-ups 168
Inspecting DNS client/server communication 170
NTP clients 172
Inspecting the NTP client/server communication 174
Summary 175

Chapter 7: Programming with Sockets 177
Basics of sockets 177
Working with TCP sockets 179
Inspecting the client/server communication 182
TCP servers 185
Inspecting client/server interaction 187
Working with UDP sockets 188
TCP port forwarding 190
A non-blocking socket I/O 193
Securing sockets with TLS/SSL 193
Inspecting standard SSL client/server communication 197
Creating a custom SSL client/server 201
Inspecting interaction between a custom SSL client/server 204
Summary 208
Chapter 8: Client and Server Applications 209
Client and server 210
An echo protocol 210
Framing 211
A simple echo server 213
Handling the received data 214
The server itself 215
A simple echo client 216
Concurrent I/O 218
Multithreading and multiprocessing 219
Threading and the GIL 220
A multithreaded echo server 222
Designing a chat server 223
A chat protocol 224
Handling data on persistent connections 225