Editing OSI Model (section)

== OSI Layer Overview ==

The OSI model goes from Layer 1 (bottom) to Layer 7 (top). Each layer depends on the functionality of the ones above and below it. Knowing what happens at each layer helps in analyzing protocols, spotting weaknesses, and understanding where specific tools operate.

{| class="wikitable"
! Layer !! Number !! What it does !! Common Examples
|-
| Application || 7 || Interfaces with user applications and defines network services || HTTP, HTTPS, DNS, FTP, SMTP, IMAP, SSH, Telnet
|-
| Presentation || 6 || Translates, encrypts, and compresses data for the application layer || TLS/SSL, ASCII, JPEG, MPEG, GZIP, Base64
|-
| Session || 5 || Manages and maintains sessions between systems || NetBIOS, RPC, SMB, PPTP, SOCKS
|-
| Transport || 4 || Provides reliable or fast delivery of data streams || TCP, UDP, SCTP, QUIC
|-
| Network || 3 || Handles routing and logical addressing across networks || IP, ICMP, IGMP, IPsec, BGP, OSPF
|-
| Data Link || 2 || Transfers frames between directly connected devices using MAC addressing || Ethernet, ARP, PPP, VLAN (802.1Q), LLDP
|-
| Physical || 1 || Moves electrical or optical signals across physical media || Ethernet (cabling), Wi-Fi (802.11), fiber optics, hubs, radio signals
|}