Editing OSI Model

= OSI Model =

The OSI model explains how data travels through a network. It splits this process into **seven layers**. Each layer has its own job — from moving raw bits to showing a website.

Understanding the OSI model helps break down complex systems, and shows where tools, attacks, or failures happen.

== OSI Layer Overview ==

The OSI model goes from Layer 1 (bottom) to Layer 7 (top). Each layer works with the ones above and below it.

{| class="wikitable"
! Layer !! Number !! What it does !! Example
|-
| Application || 7 || Talks directly with user apps || HTTP (web), DNS
|-
| Presentation || 6 || Translates and encrypts data || TLS, JPEG
|-
| Session || 5 || Keeps communication open || NetBIOS, RPC
|-
| Transport || 4 || Sends data fully and in order || TCP, UDP
|-
| Network || 3 || Routes packets between networks || IP, ICMP
|-
| Data Link || 2 || Sends frames on the local network || Ethernet, ARP
|-
| Physical || 1 || Moves bits through cables or air || Wi-Fi, fiber, cables
|}

== Easy Breakdown by Layer ==

=== Layer 1 – Physical ===  
Moves raw data (0s and 1s) over wires or radio.  
Involves: cables, Wi-Fi signals, connectors.

=== Layer 2 – Data Link ===  
Sends frames between devices on the same network.  
Uses: MAC addresses, switches, ARP.

=== Layer 3 – Network ===  
Chooses the best path for data across networks.  
Uses: IP addresses, routers, ICMP.

=== Layer 4 – Transport ===  
Breaks data into smaller parts and reassembles it.  
TCP ensures reliability, UDP focuses on speed.

=== Layer 5 – Session ===  
Keeps a connection open and manages how long systems talk.  
Used for: remote access, file sharing.

=== Layer 6 – Presentation ===  
Changes how data looks — like converting text or encrypting.  
Handles: encoding, compression, TLS.

=== Layer 7 – Application ===  
Where programs like browsers and email clients connect to the network.  
Talks via: HTTP, FTP, DNS, SMTP.

== What You Can Do with It ==

Understanding the OSI layers helps you:

* Know where a tool or attack operates  
* Analyze traffic at the right level  
* Identify weak points or misconfigurations  
* Work smarter with packet captures, scans, or payloads

== Protocols by Layer ==

{| class="wikitable"
! Layer !! Number !! Function Summary !! Common Protocols
|-
| Application || 7 || Interfaces with apps like browsers and mail || HTTP, FTP, DNS, SMTP
|-
| Presentation || 6 || Formats, encrypts, and compresses data || TLS/SSL, Base64, JPEG
|-
| Session || 5 || Manages connections and sessions || NetBIOS, PPTP, SMB
|-
| Transport || 4 || Ensures reliable or fast delivery || TCP, UDP
|-
| Network || 3 || Routes packets between networks || IP, ICMP, IPsec
|-
| Data Link || 2 || Sends frames on the local network || Ethernet, ARP
|-
| Physical || 1 || Transfers raw bits via cables or air || Wi-Fi (802.11), Ethernet (cabling)
|}

== See Also ==

* [[TCP/IP Stack]]
* [[IP Addressing]]
* [[MAC Addressing]]
* [[ARP Protocol]]
* [[Routing Basics]]