Ethical Hacking for Beginners (Chapter-7)

Ethical Hacking for Beginners (Chapter-7)

Networking Protocols and Models

Networking Protocols:- 

A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network. Essentially, it allows connected devices to communicate with each other, regardless of any differences in their internal processes, structure, or design. 

List of network protocols:-

Transmission Control Protocol (TCP)

Internet Protocol (IP)

User Datagram Protocol (UDP)

Post office Protocol (POP)

Simple mail transport Protocol (SMTP)

File Transfer Protocol (FTP)

HyperText Transfer Protocol (HTTP)

HyperText Transfer Protocol Secure (HTTPS)

Telnet

Gopher

Some other non-popular protocols:-

ARP (Address Resolution Protocol)

DHCP (Dynamic Host Configuration Protocol)

IMAP4 (Internet Message Access Protocol)

SIP (Session Initiation Protocol)

RTP (Real-Time Transport Protocol)

RLP (Resource Location Protocol)

RAP (Route Access Protocol)

L2TP (Layer Two Tunnelling Protocol)

PPTP (Point To Point Tunnelling Protocol)

SNMP (Simple Network Management Protocol)

TFTP (Trivial File Transfer Protocol)

NAT:- Network address translation (NAT) is a method of mapping an IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device.

The  NAT device accepts requests to traverse the internet from an internal machine. It then records that machine's IP address in a table and converts the IP address to the external IP address of the router. When the packet returns from its destination, the NAT device looks into its saved table of the original request and forwards the packet to the internal IP address of the system that made the original request within the LAN. And this process is so fast that one can’t even realize this whole conversion is happening on the back end.

OSI Model:-

The OSI Model consists of 7 layers. They are:-

Application Layer (Application Connected to the internet)

Presentation Layer (Standard data representation for application)

Session Layer (Manage session among applications)

Transport Layer (End to end error detection and correction)

Network Layer (Handle connection to the network by a higher layer)

Data Link Layer (provide safe communication of data over the physical network)

Physical layer (Define the physical characteristics of the network)

*Where First 3 are Software Layer and Last 3 are Hardware layer and the Middle one Transport Layer is the heart of OSI Model

We will dive deep into all of these layers in another chapter.

TCP/IP Model:-

TCP/IP model consists of 4 layers only. 

Application Layer (In this layer App and processes running on the network.)

Transport layer (Provides end to end data delivery service)

Internet Layer (Make datagram and handles data routines)

Network Layer (Provides routines allowing access to the physical network)

Will discuss all of these layers in detail in the future.

In the next chapter, we will discuss IP Addresses in detail.

Till then Happy Learning!

Ethical Hacking for Beginners (Chapter-6)

Ethical Hacking for Beginners (Chapter-6)

 

Networking Basics

What is Networking?

A network refers to two or more connected computers that can share resources such as data, a printer, an Internet connection, applications, or a combination of these resources.

Types of Network:- 

1. LAN (Local Area Network):- Mostly covers buildings or a set of closely related buildings

2. MAN (Metropolitan Area Network):- Covers a metropolitan area or a small geographic area such as a small town.

3. WAN (Wide Area Network):- Covers countries, or a large geographic area.

Open System:- A system that is connected to internet and ready to communicate is called open system

Closed System:- A system is not connected to the internet and can’t be communicated with.

Network topologies:- The arrangement of devices connected to a network. 

Some examples are:- Star, bus, Delta, ring, mesh, point to point, daisy chain, tree, hybrid etc.

image source:- Wikimedia commons

Network Components:- A network connection may have multiple other devices by which communication also occurs. Eg:- Router, switch, hub, bridge, wireless router, etc.

Unique identifiers of a network:-

Each device in a network is associated with some unique identifiers by using which a device can be identified.

1. Host Name:- Each device in the network is associated with a unique device name known as Hostname which you can get t know by typing “hostname” in the command prompt (without quotation) 

2. IP Address:- It is the logical address of a device connected to a network. It is a unique number assigned to every device connected to the internet. It has 2 versions IPv4 (32 bit long) and IPv6 (128 bit long). You can see it by typing “iconfig” in the command prompt for windows and “ifconfig” in Linux (without quote)

3. MAC Address:- This is the physical address. It is the unique identifier attached with each device NIC card (network interface card). It is 48 bit long. You can check it by using the same command “ipconfig/all”

4. Port:- Can be referred to as a logical channel using which data packets are transferred to any applications. It is a 16-bit long integer number and we have 216  ports available. Start from 0-65535 total 65536 ports. You can check by typing “netstat -a” by typing in the command prompt which ports are currently being used.

List of some important ports:-

20 FTP

21 FTP

22 SSH

23 Telnet

25 SMTP

53 DNS

69 TFTP

80 HTTP

88 Kerberos

110 POP3

123 NTP

135 Microsoft's RPC

137-139 Microsoft's NetBIOS

143 IMAP

161 SNMP

389 LDAP

443 HTTPS or HTTP over SSL

445 SMB

500 IKE

514 syslog

3389 RDP

 

5. Socket:- Combination of port and IP address is called socket.

In the next chapter, we will discuss some networking protocols. 

Till then Happy Learning!.