DEV Community: Vinay Keshava

Python Day-1

Vinay Keshava — Tue, 24 Aug 2021 17:54:27 +0000

1.Python Interpreter

Python can launched by typing python3 in the prompt of you linux terminal .

' >>> ' this is python prompt,waiting for the input.
Python interpreter can be used as a calculator,simple arithematic calculations can be using the operators +,-,*,/,(()) .

Variables can also be used in the python interpreter and values are assigned to it.
In the example shown width and height are variables and values are assigned to it , their value is calculated and stored in 'area', later using the print() function the value of area is printed.

Python supports integer, floating, decimal, fraction and also python has builtin functions for complex number it used 'j' to indicate the imaginary part 3+5j

-> To open a file in interpreter mode
python3 -i filename.py

2.Strings
-> Single Quotes: Identifier representation.
-> Double Quotes: String representation.
-> Triple Quotes: Multiline Texts
The below table represents how python uses indices

+---+---+---+---+---+---+
| P | y | t | h | o | n |
+---+---+---+---+---+---+
0 1 2 3 4 5 6

-6 -5 -4 -3 -2 -1

NTP,ARP

Vinay Keshava — Sun, 01 Aug 2021 09:23:19 +0000

NTP stand for Network Time Protocol
when two machines are communicating the time has to be synced.
If the time wont be in sync with each other there would be miscommunication so for this reason the time has to be updated using NTP server where the server shows the exact time .

This protocol uses it for keeping the time in sync.

ARP Address Resolution Protocol is used to find the hardware address or the MAC address of the destination machine
https://study-ccna.com/arp/

Gnome Boxes

Vinay Keshava — Sat, 31 Jul 2021 18:37:27 +0000

Gnome Boxes

I have been using the oracle virtualbox since a long time it was slow and had to configure heavily.
I just found out i had the Gnome boxes on my host computer fedora .
Gnome boxes is simple fast, minimalistic.

I have installed Antix linux as one of the boxes and after using it for a while it simple fast and responsive
But in Boxes i cannot find options about increasing the display size that was the disadvantage.

TCP/ IP Network Model

Vinay Keshava — Wed, 28 Jul 2021 12:10:08 +0000

TCP/IP Network model
I was intrested in security so i started using tools without knowing the basic knowledge of it , i started with Nmap a port scanning tool on kali linux scanning random ip addresses i did not understand what TCP UDP port was,later started learning about networks.

TCP/IP network model or Transmission Control Protocol/Internet Protocol Network model.
TCP/IP network model has five layers they are:

Application Layer
Transport Layer
Network Layer
Data-link Layer
Physical Layer

Each layer a different protocols
1.Application layer has HTTP,HTTPS,SMTP,FTP,TELNET.

2.Transport layer has TCP/UDP

TCP stands for Transmission Control Protocol and User Datagram Protocol an example for UDP is video call where continous delivery of packets, if a packet is lost it does not care ,while in TCP if a packet is lost it asks the sender to send it again.

When the data arrives at the transport layer, the protocols at the layer start the process of data encapsulation. The transport layer encapsulates the application data into transport protocol data units.

The transport layer protocol creates a virtual flow of data between the sending and receiving application, differentiated by the transport port number. The port number identifies a port, a dedicated location in memory for receiving or sending data. In addition, the transport protocol layer might provide other services, such as reliable, in order data delivery. The end result depends on whether TCP, SCTP, or UDP handles the information

Establishing a TCP Connection

TCP uses segments to determine whether the receiving system is ready to receive the data. When the sending TCP wants to establish connections, TCP sends a segment that is called a SYN to the TCP protocol on the receiving host. The receiving TCP returns a segment that is called an ACK to acknowledge the successful receipt of the segment. The sending TCP sends another ACK segment, then proceeds to send the data. This exchange of control information is referred to as a three-way handshake.

3.Network layer - IP (logical addressing )ICMP

https://youtu.be/OTwp3xtd4dg
https://docs.oracle.com/cd/E18752_01/html/816-4554/ipov-29.html#ipov-32