OSI Model
- What it is
- How many layers it has
- How it is organized
What is a LAN -Typical usage
- Typical geographical size
What is a WAN
- Typical usage
- Typical geographical size
What is the Internet
- What is an IP address
- What are the 2 types of IP address
- What is localhost
- What is a subnet
- Why IPv6 was created
TCP/UDP -What are the 2 mainly used data transfer protocols for IP (transfer level on the OSI schema)
- What is the main difference between TCP and UDP
- What is a port
- Memorize SSH, HTTP and HTTPS port numbers
- What tool/protocol is often used to check if a device is connected to a network
- Every computer should have a unique IP to be able to communicate to other devices.
- There are two types of IP (IPv4, IPv6 'IPng')
- IPv4 is consisting of 32 bits (4 bytes), (Example: 0,0,0,0 OR 255,255,255,255)
- Each number in the IPv4 is the decimal representation of a binary number and it ranges between 0 to 255
- there are some reserved IPs like:
- 0.0.0.0 special-purpose IP
- 255.255.255.255 Broadcast Address
- 127.0.0.1 Loopback Address
- And there are other reserved IPs that are divided into 5 classes (A, B, C, D, E).
- Common Problem & Resolution:
- People may by accident assign the same IP for two different devices, and this will create a conflict "IP Conflict" Warning and to avoid this you can use DHCP (Dynamic Host Configuration Protocol) to assign addresses to devices and computers dynamically.
- https://www.bleepingcomputer.com/tutorials/ip-addresses-explained/
- Is the newer version of IP and the successor of IPv4 as the IPv4s are limited and will run out in the future
- It's 128 bits (16 bytes), (Example 3ffe:1900:4545:3:200:f8ff:fe21:67cf)
- Advantages of IPv6: No need to NAT (Network Address Translation) or DHCP () any more, no more private address collisions and more.
- https://www.webopedia.com/insights/ipv6-ipv4-difference/
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Aspect Public IP Address Private IP Address Definition Unique identifier assigned to a device directly connected to the internet Unique identifier assigned to a device within a local network Accessibility Accessible from anywhere on the internet Limited to the local network Assigning Authority Assigned by Internet Service Providers (ISPs) Assigned by routers or network address translators (NATs) Uniqueness Unique across the entire internet Reusable within different local networks Range Varies depending on the ISP’s allocation Common private IP address ranges include 192.168.0.0-192.168.255.255, 172.16.0.0-172.31.255.255, and 10.0.0.0-10.255.255.255 Purpose Identifying devices on the internet and enabling communication between devices across the internet Identifying devices within a local network and facilitating internal communication between devices Use Cases Hosting websites, online game servers, VPN connections, remote access to a computer or network Assigning IP addresses to devices in home networks, office networks, printers, servers, and other network-connected devices Addressing Provided by ISPs through static (permanent) or dynamic (temporary) assignment Assigned by routers or network administrators Security Subject to potential security risks and external access attempts Generally more secure due to the restricted local network access Configuration Automatically assigned by ISPs or configured manually Assigned and managed by the local network administrator
- is a logical construct used to uniquely identify a specific process or application running on a networked device. Ports are essential for enabling communication between different applications or services over a network.
- It's usually used with IP like this (Example 192.168.1.100:8080, localhost:22, example.com:443)
- Port 80 (HTTP)
- Port 443 (HTTPS)
- Port 22 (SSH, SFTP)
- Port 25 (SMPT, Simple Mail Transfer Protocol)
- Port 53 (DNS)
List of Default Ports: https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
- LAN: Local Area Network is a computer network that interconnects computers within a limited area such as a residence, school, laboratory. LANs are typically characterized by their relatively small geographic scope and high data transfer rates compared to wide area networks (WANs).
- WAN: Wide Area Network is a telecommunications network that extends over a large geographical area, connecting multiple LANs and other types of networks. Unlike LANs, which are confined to a limited geographic area such as a single building or campus, WANs can span cities, countries, or even continents.
- is a unique identifier assigned to network interface card (NIC) for communications on a network. It's also known as a hardware address or physical address.
- Every MAC is globally unique means that no two MACs has the same MAC.
- It's representing in 48 bits (6 bytes), expresses in hexadecimal format (e.g., 00:1A:2B:3C:4D:5E)
- https://whatismyipaddress.com/mac-address
- Is the hostname that the current computer used to access it, and the name of localhost is used for loopback purposes.
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Both of them are used to sent bits of data called Packets, and both of them are built on top of the IP, as the data is sent to an IP address.
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Whenever a browser create a request to a web server, it sends a TCP Packets and the same with the server when it reply with a response, it sends back a TCP Packets.
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- TCP is all about RELIABILITY as the TCP packets are being tracked in order to avoid any data loss or corruption.
- And it's being achieved through two steps:
- It's numbering the TCP Packets.
- Error Check, by making the recipient to send an assertion that he got the message (Packets), which causes some latency.
- TCP relies on a three-way handshake (synchronization, synchronization acknowledgment, and final acknowledgment)
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- UDP is all about SPEED & NO LATENCY, When the sender send a UDP packets, it does not care if the recipient got it or not and will continue send more and more UDP packets, the lost UDP packets will be lost forever and will not be sent again.
- It's used in the Live Streaming and Online gaming ...
- UDP enables continuous data transmission (i.e., response) without acknowledging or confirming the connection
- UDP enables continuous data transmission (i.e., response) without acknowledging or confirming the connection
- https://www.spiceworks.com/tech/networking/articles/tcp-vs-udp/
- https://www.howtogeek.com/190014/htg-explains-what-is-the-difference-between-tcp-and-udp/
List of TCP and UDP port numbers: https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
(Open Systems Interconnection Model)
| Layer | Description / Data Unit | Protocols | Interactions | Examples |
|---|---|---|---|---|
| 7- Application | Data | HTTP, SMTP, FTP | Interacts directly with end-user | Web browsers, Email clients |
| 6- Presentation | Data | SSL/TLS, JPEG, GIF | Handles data encryption and formatting | Encryption libraries, Image viewers |
| 5- Session | Data | SSH, NetBIOS | Establishes, manages, and terminates sessions | Remote login, File sharing |
| 4- Transport | Segments (Port) | TCP, UDP | Ensures reliable data delivery | TCP/IP, UDP/IP |
| 3- Network | Packets (IP) | IP, ICMP, ARP | Routes data across networks | Routers, IP switches |
| 2- Data Link | Frames (MAC) | Ethernet, PPP | Provides node-to-node data transfer | Network interface cards (NICs) |
| 1- Physical | Bits | Ethernet, DSL | Transmits raw bit stream over physical medium | Cables, Hubs, DSL modems |
(Transmission Control Protocol/Internet Protocol) (Department of Defense)
- https://www.youtube.com/watch?v=pb2hhd1fhAs&list=PLH-n8YK76vIiuIZoWvHL7AvtrDV7hR3He&index=8
- pdf that mentioned in the previous tutorial: https://www.mediafire.com/file/ynm9mrzlphsfwhj/TCPIP_and_DoD_Model.pdf/file
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