Python Cheat Sheet

Python is an open-source and versatile programming language used by thousands of web developers, data scientists, and software engineers. It is very popular because it has extensive support libraries, user-friendly data structures, and a vibrant support community.

This Python Cheat Sheet can serve as a quick reference for system administrators and network administrators.

We include all essential categories and items including: network programming libraries, keywords, variables and data types, strings, lists, and more.

Basic Python Libraries for Network Admin

Here is the list of basic Python libraries with a brief explanation.

Name	Explanation
PIP	Package manager for Python.
pypcap	Python interface to pcap a packet capture library.
PyPI	Repository of open-source Python packages.
Paramiko	It is a Python interface around SSH networking concepts.
EDDIE Tool	Python agent used for system and network monitoring, security, and performance analysis.
pycos	It provides an Asynchronous Socket class to convert Python's blocking socket to a non-blocking socket.
Diesel	Framework to write reliable and scalable network applications in Python.
NAPALM	A Python.
Celery	It is a task queue implementation for Python web applications to asynchronously execute work outside the HTTP request-response cycle.

Python Keywords

Python has a set of keywords (or reserved words) used to define the syntax of the coding. You can not use these words as identifiers, functions, or variable names. Here is a list of such keywords with examples.

Keyword	Explanation	Example
False, True	Boolean value, result of comparison operations	False == (1 > 2), True == (1 < 2)
and, or, not	Logical operators	x, y = True, False (x or y) == True # True (x and y) == False # True (not y) == True # True
break	Ends loop prematurely	while(True): break print (“Hi How R U?”)
continue	Finishes current loop	while(True): continue print (“200”)
class def	Defines a new class Defines a new function	class Bear def __init__(self): self.content = 1.0 def drink(self): self.content = 0.0backs = Bear() backs.drink()
if, elif, else	Used for a conditional program that starts with if, tries the elif, and finishes with else.	x = int(input(“type your value: “)) if x > 4: print(“Big”) elif x == 4: print(“Medium”) else: print(Small”)
for, while		for a in [0,1,2,3]: print(a)b = 1 while b < 4: print(b) b = b + 1
in	Checks whether element is in sequence.	30 in [10, 30, 40, 70]     # True
is	Checks whether both elements point to the same object.	a = b = 5 a is b # True [5] is [5] # False
None	Empty value constant	def f(): a = 3 f() in None # True
lamda	Function with no name	(lamda a: a + 4)(4)      # returns 8
return	Terminates execution of the function and passes the flow of performance to the caller.	def incrementor(a): return a + 1 incrementor(3)               # return 4

Data Types

In Python programming, everything is an object. Every value in Python is called an “object,” and every object has a specific data type.

There are various data types in Python. Some of the essential types are listed below:

• int An integer number that represents an object or number such as 3, 4, 5, etc.
• float Represents ‘floating-point numbers' such as 0.5, 1.25, 2.0, etc.
• Strings A collection of one or more characters put in a single quotes, double-quotes, or triple quotes.

Data Types
Text Type	str
Numeric Types	int, float, complex
Sequence Types	list, tuple, range
Mapping Type	dict
Set Types	set, frozenset
Boolean Type	bool
Binary Types	bytes, bytearray, memoryview

Math Operators

Math operators in Python perform mathematical operations like addition, subtraction, multiplication, and division. Here we list all of the math operators with explanations and examples.

Keyword	Explanation	Example
**	Exponent	3 ** 2 = 9
%	Modulus/Remainder	22 % 8 = 6
//	Integer division	20 // 8 = 2
/	Division	22 / 8 = 2.75
*	Multiplication	2 * 3 = 6
–	Subtraction	8 – 2 = 6
+	Addition	2 + 8 = 10
==	Equal to
!=	Not equal to
<	Less than
>	Greater than
>=	Greater than or Equal to
<=	Less than or Equal to

Network Services in Python

There are two levels of network services in Python.

• High-level access This service helps programmers access the application-level network protocols.
• Low-level access This service allows you to access the socket support for the operating systems by using Python libraries. You can use low-level access to implement connection-less and connection-oriented protocols for performing network programming.

There are several methods available that help network administrators manage the connections. Some of them are listed below.

Method	Explanation
listen()	Used to establish and start TCP listeners.
bind()	Used to bind-address to the socket.
connect()	Used to make a connection with the TCP server.
accept()	Used to accept TCP client connection, waiting until a connection arrives.
recv()	Used to receive TCP messages.
close()	Used to close a socket.
Send()	Used to send messages.
socket.gethostname()	Used to retrieve the hostname.
mysocket.accept()	Returns a tuple with the remote address that has connected.
mysocket.bind( address )	Used to attach the specified address to the socket.
mysocket.getpeername()	Used to get the remote address where the socket is connected.
mysocket.connect( address )	Used to assign the data sent through the socket to the given remote address.
mysocket.getsockname()	Used to retrieve the address of the socket’s local endpoint.
import socket socket.getservbyname(‘domain name')	Used to obtain port number using the domain name.
import socket socket.has_ipv6	Used to check support for IPV6.
ipaddress.ip_address(‘192.168.0.1')	Used to assign an IP address.
ipaddress.ip_network(‘192.168.0.1/24')	Used to determine the IPv4 or IPv6 version.
host4=ipaddress.ip_interface(‘192.168.0.1/24') host4.network	Used to obtain the network from an interface.
net4=ipaddress.ip_network(‘192.168.0.1/24') net4.num_addresses	Used to find the number of IP addresses in the specified network.
net4=ipaddress.ip_network(‘192.168.0.1/24') net4.netmask	Used to find the netmask of the specified IP address.

Python Internet Modules

Here is the list of all Python internet modules.

Protocol	Explanation	Port	Python Module
Gopher	Used to transfer documents.	70	Gopherlib, urllib
Telnet	Used to open a command line on a remote computer.	23	telnetlib
IMAP4	Used for fetching emails from the mail server.	143	impalib
POP3	Used for fetching emails from the mail server.	110	poplib
SMTP	Used for sending emails.	25	smtlib
FTP	Used for file transfers.	20	Ftblib, urllib
MNTP	Usenet news	119	mntplib
HTTP	Used to access web pages over the internet.	80	Httplib, urllib

Conclusion

We've included all useful Python commands, libraries, and code that you can use as a quick reference in the above guide. Feel free to let us know in the comments if you have any questions.