Network Protocols

Comprehensive collection of 78+ essential network protocols covering all OSI layers from physical to application layer communications.

78
Network Protocols
Protocols across all OSI layers
56
Application Layer
Protocols at application layer
5
Transport Layer
Protocols at transport layer
8
Network Layer
Protocols at network layer

HTTP (HyperText Transfer Protocol)

Layer 7 (Application)
Port: 80 (HTTP), 443 (HTTPS)

Application layer protocol for transmitting hypertext documents between web servers and clients.

Standard
RFC 2616 (HTTP/1.1), RFC 7540 (HTTP/2), RFC 9114 (HTTP/3)
How Used
Client-server communication for requesting and serving web content
Security
HTTPS (HTTP over TLS/SSL) for encrypted communication
Where Used
  • Web browsing
  • RESTful APIs
  • Web services
  • Content delivery
Example Usage
GET https://api.example.com/users - retrieves user data from a web API
Key Characteristics
Stateless protocol Request-response model Text-based headers Supports multiple methods (GET, POST, PUT, DELETE)

HTTPS (HTTP Secure)

Layer 7 (Application)
Port: 443

Secure version of HTTP using TLS/SSL encryption for secure web communication.

Standard
RFC 2818, RFC 5246 (TLS 1.2), RFC 8446 (TLS 1.3)
How Used
Encrypted HTTP communication using TLS/SSL certificates
Security
End-to-end encryption, certificate validation, integrity protection
Where Used
  • Secure web browsing
  • E-commerce transactions
  • Online banking
  • Secure API communications
Example Usage
https://bank.example.com/login - secure login to banking website
Key Characteristics
Encrypted data transmission Server authentication Data integrity Perfect Forward Secrecy (PFS)

TCP (Transmission Control Protocol)

Layer 4 (Transport)
Port: N/A (Protocol)

Reliable, connection-oriented transport protocol ensuring ordered and error-checked data delivery.

Standard
RFC 793, RFC 1122, RFC 5681
How Used
Establishes reliable connections using three-way handshake
Security
Sequence numbers, checksums, acknowledgments for data integrity
Where Used
  • Web browsing (HTTP/HTTPS)
  • Email (SMTP, IMAP, POP3)
  • File transfer (FTP, SFTP)
  • Remote access (SSH, Telnet)
Example Usage
Web browser connecting to server: SYN → SYN-ACK → ACK handshake
Key Characteristics
Connection-oriented Reliable delivery Flow control Congestion control

UDP (User Datagram Protocol)

Layer 4 (Transport)
Port: N/A (Protocol)

Fast, connectionless transport protocol for applications requiring speed over reliability.

Standard
RFC 768
How Used
Sends datagrams without establishing connections
Security
Basic checksum only, application must handle security
Where Used
  • DNS queries
  • Video streaming (RTSP)
  • Online gaming
  • VPN tunneling
  • DHCP
Example Usage
DNS query: client sends UDP packet to DNS server on port 53
Key Characteristics
Connectionless Low overhead No delivery guarantee Fast transmission

IP (Internet Protocol)

Layer 3 (Network)
Port: N/A (Protocol)

Network layer protocol responsible for routing packets across interconnected networks.

Standard
RFC 791 (IPv4), RFC 8200 (IPv6)
How Used
Routes packets between networks using IP addresses
Security
Limited built-in security, relies on upper layers (IPSec for IPv6)
Where Used
  • Internet routing
  • LAN/WAN communication
  • VPN connections
  • All TCP/UDP communications
Example Usage
Packet from 192.168.1.100 to 8.8.8.8 routed through multiple hops
Key Characteristics
Connectionless Best-effort delivery Hierarchical addressing Fragmentation support

DNS (Domain Name System)

Layer 7 (Application)
Port: 53 (UDP/TCP)

Hierarchical naming system that translates human-readable domain names to IP addresses.

Standard
RFC 1034, RFC 1035, RFC 8499
How Used
Resolves domain names to IP addresses through hierarchical queries
Security
DNSSEC for authentication, DNS over HTTPS (DoH), DNS over TLS (DoT)
Where Used
  • Web browsing
  • Email routing
  • Service discovery
  • Load balancing
Example Usage
Resolving www.google.com → queries root servers → .com servers → google.com servers
Key Characteristics
Hierarchical structure Distributed database Caching mechanism Multiple record types

DHCP (Dynamic Host Configuration Protocol)

Layer 7 (Application)
Port: 67 (Server), 68 (Client)

Network service that automatically assigns IP addresses and network configuration to devices.

Standard
RFC 2131, RFC 3315 (DHCPv6)
How Used
Four-step process: DISCOVER → OFFER → REQUEST → ACKNOWLEDGE
Security
DHCP snooping, option 82, DHCP authentication
Where Used
  • Home networks
  • Corporate LANs
  • WiFi networks
  • Mobile device connectivity
Example Usage
Laptop connects to WiFi: broadcasts DISCOVER → router sends OFFER → laptop sends REQUEST → router sends ACK with IP
Key Characteristics
Automatic IP assignment Lease-based allocation Configuration distribution Address pool management

FTP (File Transfer Protocol)

Layer 7 (Application)
Port: 21 (Control), 20 (Data)

Application protocol for transferring files between computers over a network.

Standard
RFC 959, RFC 3659
How Used
Uses separate control and data connections for file operations
Security
Plain text by default, FTPS (FTP over SSL) or SFTP (SSH FTP) for security
Where Used
  • Website file uploads
  • Software distribution
  • Backup systems
  • Content management
Example Usage
Upload website files: ftp://server.com → login → PUT index.html
Key Characteristics
Two-channel protocol Active/passive modes ASCII and binary transfer Directory navigation

SSH (Secure Shell)

Layer 7 (Application)
Port: 22

Cryptographic network protocol for secure remote access and command execution.

Standard
RFC 4251, RFC 4252, RFC 4253, RFC 4254
How Used
Establishes encrypted channel for secure communication
Security
Strong encryption, key-based authentication, host verification
Where Used
  • Remote server administration
  • Secure file transfer (SFTP)
  • Tunneling other protocols
  • Git repository access
Example Usage
ssh user@server.com → encrypted login and command execution
Key Characteristics
Strong encryption Multiple authentication methods Port forwarding Compression support

SMTP (Simple Mail Transfer Protocol)

Layer 7 (Application)
Port: 25 (SMTP), 587 (Submission), 465 (SMTPS)

Protocol for sending email messages between mail servers and email clients.

Standard
RFC 5321, RFC 6531, RFC 3207 (STARTTLS)
How Used
Client connects to server, authenticates, and transfers email messages
Security
STARTTLS for encryption, SMTP-AUTH for authentication, SPF/DKIM/DMARC for validation
Where Used
  • Email sending
  • Mail server communication
  • Automated notifications
  • Newsletter distribution
Example Usage
Email client → SMTP server → recipient's mail server → recipient's inbox
Key Characteristics
Text-based protocol Store-and-forward mechanism Multiple recipient support Extension mechanisms

SNMP (Simple Network Management Protocol)

Layer 7 (Application)
Port: 161 (Agent), 162 (Manager/Traps)

Protocol for collecting and organizing information about managed devices on IP networks.

Standard
RFC 3411-3418 (SNMPv3), RFC 1157 (SNMPv1)
How Used
Manager queries agents using GET/SET operations, agents send traps
Security
SNMPv3 with authentication and encryption, community strings in older versions
Where Used
  • Network monitoring
  • Device management
  • Performance monitoring
  • Network troubleshooting
Example Usage
Network monitor queries router via SNMP to get interface statistics
Key Characteristics
Manager-agent architecture MIB (Management Information Base) Trap notifications Extensible framework

ICMP (Internet Control Message Protocol)

Layer 3 (Network)
Port: N/A (Protocol)

Network layer protocol used for error reporting and network diagnostics.

Standard
RFC 792 (ICMPv4), RFC 4443 (ICMPv6)
How Used
Sends control and error messages between network devices
Security
Often filtered by firewalls, can be used for reconnaissance
Where Used
  • Network diagnostics (ping)
  • Error reporting
  • Path MTU discovery
  • Network troubleshooting
Example Usage
ping google.com → ICMP Echo Request → ICMP Echo Reply
Key Characteristics
Error reporting Network diagnostics No data payload Various message types

ARP (Address Resolution Protocol)

Layer 2 (Data Link)
Port: N/A (Protocol)

Protocol that maps IP addresses to MAC addresses on local network segments.

Standard
RFC 826
How Used
Broadcasts ARP request to find MAC address for a given IP address
Security
Vulnerable to ARP spoofing attacks, use ARP tables monitoring
Where Used
  • Local network communication
  • Ethernet networks
  • WiFi networks
  • IP to MAC resolution
Example Usage
Host needs to send packet to 192.168.1.1 → ARP broadcast 'Who has 192.168.1.1?' → Router replies with MAC address
Key Characteristics
Broadcast-based Local network only Cache mechanism Request-reply model

BGP (Border Gateway Protocol)

Layer 3 (Network)
Port: 179

Exterior gateway protocol for exchanging routing information between autonomous systems on the Internet.

Standard
RFC 4271, RFC 7606
How Used
Exchanges routing information between autonomous systems using path vector algorithm
Security
BGP hijacking concerns, RPKI for route validation, route filtering
Where Used
  • Internet routing
  • ISP interconnection
  • Enterprise multi-homing
  • Content delivery networks
Example Usage
ISP announces routes to its IP blocks to neighboring ISPs
Key Characteristics
Path vector protocol Policy-based routing AS-path information Incremental updates

OSPF (Open Shortest Path First)

Layer 3 (Network)
Port: N/A (IP Protocol 89)

Interior gateway protocol that uses link-state routing algorithm for IP networks.

Standard
RFC 2328 (OSPFv2), RFC 5340 (OSPFv3)
How Used
Builds network topology database and calculates shortest paths
Security
Authentication mechanisms, area-based segmentation
Where Used
  • Enterprise networks
  • ISP internal routing
  • Data center networks
  • Campus networks
Example Usage
Router failure triggers LSA updates, all routers recalculate paths
Key Characteristics
Link-state protocol Hierarchical design Fast convergence Load balancing support

SMTP (Simple Mail Transfer Protocol)

Layer 7 (Application)
Port: 25 (SMTP), 587 (Submission), 465 (SMTPS)

Application layer protocol for sending and routing email messages between mail servers.

Standard
RFC 5321, RFC 6152, RFC 3207 (STARTTLS)
How Used
Push protocol for sending emails from client to server or server to server
Security
STARTTLS encryption, SMTP authentication, SPF, DKIM, DMARC
Where Used
  • Email transmission between servers
  • Outgoing email from email clients
  • Automated system notifications
  • Marketing email campaigns
Example Usage
Sending email: HELO mail.example.com → MAIL FROM → RCPT TO → DATA → email content → QUIT
Key Characteristics
Text-based protocol Push-based delivery Store and forward Multiple recipient support

POP3 (Post Office Protocol v3)

Layer 7 (Application)
Port: 110 (POP3), 995 (POP3S)

Application layer protocol for retrieving email from a mail server to a single client device.

Standard
RFC 1939, RFC 2595 (POP3 over TLS)
How Used
Downloads emails from server to client and typically deletes them from server
Security
POP3S (POP3 over SSL/TLS), APOP authentication
Where Used
  • Email retrieval for offline reading
  • Single device email access
  • Limited storage email accounts
  • Simple email client configurations
Example Usage
Email retrieval: USER john@example.com → PASS password → LIST → RETR 1 → DELE 1 → QUIT
Key Characteristics
Download and delete model Single client access Stateless protocol Simple command structure

IMAP (Internet Message Access Protocol)

Layer 7 (Application)
Port: 143 (IMAP), 993 (IMAPS)

Application layer protocol for accessing and managing email messages stored on a mail server.

Standard
RFC 3501, RFC 2595 (IMAP over TLS)
How Used
Allows multiple clients to access same mailbox with server-side storage
Security
IMAPS (IMAP over SSL/TLS), SASL authentication mechanisms
Where Used
  • Multi-device email synchronization
  • Server-side email storage
  • Shared mailbox access
  • Advanced email organization
Example Usage
Email management: LOGIN → SELECT INBOX → SEARCH FROM 'boss' → FETCH message → STORE flags
Key Characteristics
Server-side storage Multi-client access Stateful protocol Advanced searching and organizing

SSH (Secure Shell)

Layer 7 (Application)
Port: 22

Cryptographic network protocol for operating network services securely over an unsecured network.

Standard
RFC 4251-4254, RFC 8709
How Used
Establishes encrypted tunnel for secure remote access and file transfers
Security
Strong encryption, public key authentication, host key verification
Where Used
  • Remote server administration
  • Secure file transfer (SFTP, SCP)
  • Port forwarding and tunneling
  • Git repository access
Example Usage
Remote login: ssh user@192.168.1.100 → authenticate → encrypted shell session
Key Characteristics
End-to-end encryption Multiple authentication methods Port forwarding capabilities Session multiplexing

Telnet

Layer 7 (Application)
Port: 23

Application layer protocol providing bidirectional interactive text-oriented communication over networks.

Standard
RFC 854, RFC 855
How Used
Provides virtual terminal connection to remote hosts
Security
No encryption (plain text), largely replaced by SSH
Where Used
  • Legacy system administration
  • Network device configuration
  • Testing network connectivity
  • Debugging network services
Example Usage
Remote access: telnet 192.168.1.1 → login → command line interface
Key Characteristics
Plain text protocol Virtual terminal interface Simple command structure Legacy protocol

SNMP (Simple Network Management Protocol)

Layer 7 (Application)
Port: 161 (Agent), 162 (Manager)

Application layer protocol for collecting and organizing information about managed devices on IP networks.

Standard
RFC 1157 (SNMPv1), RFC 3414 (SNMPv3)
How Used
Manager polls agents on network devices for status and configuration data
Security
SNMPv3 with authentication and encryption, community strings in v1/v2c
Where Used
  • Network monitoring and management
  • Device performance tracking
  • Configuration management
  • Fault detection and alerting
Example Usage
Monitor router: GET request for system.sysUpTime.0 → response with uptime value
Key Characteristics
Manager-agent architecture MIB (Management Information Base) Polling and trap mechanisms Standardized data structure

LDAP (Lightweight Directory Access Protocol)

Layer 7 (Application)
Port: 389 (LDAP), 636 (LDAPS)

Application layer protocol for accessing and maintaining distributed directory information services.

Standard
RFC 4510-4519, RFC 2830 (LDAP over TLS)
How Used
Queries and modifies directory entries using distinguished names (DN)
Security
LDAPS (LDAP over SSL/TLS), SASL authentication, access control lists
Where Used
  • Active Directory authentication
  • Corporate directory services
  • Single sign-on (SSO) systems
  • Contact and user management
Example Usage
User lookup: BIND → SEARCH base='dc=company,dc=com' filter='(uid=john)' → RESULT
Key Characteristics
Hierarchical directory structure Distinguished name addressing Standardized schema Cross-platform compatibility

NTP (Network Time Protocol)

Layer 7 (Application)
Port: 123

Networking protocol for clock synchronization between computer systems over packet-switched networks.

Standard
RFC 5905, RFC 4330 (SNTP)
How Used
Hierarchical system of time servers providing accurate time reference
Security
NTP authentication, access control, symmetric key authentication
Where Used
  • System clock synchronization
  • Distributed system coordination
  • Log file timestamp accuracy
  • Financial transaction timestamping
Example Usage
Time sync: client queries time.nist.gov → receives timestamp → adjusts local clock
Key Characteristics
Hierarchical stratum architecture Microsecond precision Fault tolerance Automatic server selection

ICMP (Internet Control Message Protocol)

Layer 3 (Network)
Port: N/A (Protocol)

Supporting protocol in the IP suite used for error reporting and operational information.

Standard
RFC 792 (ICMPv4), RFC 4443 (ICMPv6)
How Used
Sends control messages about network conditions and errors
Security
Limited security, can be used for reconnaissance and DoS attacks
Where Used
  • Network diagnostics (ping, traceroute)
  • Error reporting between routers
  • Path MTU discovery
  • Network troubleshooting
Example Usage
Ping test: ICMP Echo Request to 8.8.8.8 → ICMP Echo Reply with round-trip time
Key Characteristics
Error reporting mechanism Diagnostic tool support No data payload Router-to-host communication

ARP (Address Resolution Protocol)

Layer 2 (Data Link)
Port: N/A (Protocol)

Communication protocol used for discovering link layer addresses associated with IP addresses.

Standard
RFC 826, RFC 5227 (IPv4 ACD)
How Used
Broadcasts requests to find MAC address for given IP address
Security
ARP spoofing attacks, static ARP entries, ARP inspection
Where Used
  • Local network communication
  • IP to MAC address mapping
  • Ethernet frame delivery
  • Switch learning processes
Example Usage
Address resolution: Who has 192.168.1.1? → 192.168.1.1 is at 00:11:22:33:44:55
Key Characteristics
Broadcast-based resolution Cache mechanism Local network scope Hardware address mapping

RARP (Reverse Address Resolution Protocol)

Layer 2 (Data Link)
Port: N/A (Protocol)

Network protocol used by diskless workstations to find their IP address from their MAC address.

Standard
RFC 903
How Used
Client broadcasts MAC address to get IP address from RARP server
Security
Limited security, largely replaced by DHCP and BOOTP
Where Used
  • Diskless workstations
  • Network boot processes
  • Embedded systems
  • Legacy network configurations
Example Usage
Boot process: diskless client broadcasts MAC → RARP server responds with assigned IP
Key Characteristics
Reverse of ARP Broadcast-based request Requires RARP server Legacy protocol

STP (Spanning Tree Protocol)

Layer 2 (Data Link)
Port: N/A (Protocol)

Network protocol that builds a loop-free logical topology for Ethernet networks.

Standard
IEEE 802.1D, IEEE 802.1w (RSTP), IEEE 802.1s (MSTP)
How Used
Automatically disables redundant paths to prevent network loops
Security
BPDU Guard, Root Guard, port security features
Where Used
  • Ethernet switch networks
  • Loop prevention in LANs
  • Network redundancy management
  • Campus network design
Example Usage
Loop prevention: Bridge Priority + MAC → Root bridge selection → port states (blocking/forwarding)
Key Characteristics
Loop prevention Automatic topology discovery Root bridge election Port state management

VLAN (Virtual Local Area Network)

Layer 2 (Data Link)
Port: N/A (Standard)

Method of creating logically separate network segments within a single physical network infrastructure.

Standard
IEEE 802.1Q, IEEE 802.1ad (Q-in-Q)
How Used
Tags Ethernet frames with VLAN ID to separate logical networks
Security
VLAN hopping protection, private VLANs, access control
Where Used
  • Network segmentation
  • Broadcast domain isolation
  • Security policy enforcement
  • Traffic management
Example Usage
VLAN configuration: VLAN 100 (Sales) + VLAN 200 (IT) on same physical switch
Key Characteristics
Logical network separation Broadcast domain control Frame tagging (802.1Q) Scalable network design

PPP (Point-to-Point Protocol)

Layer 2 (Data Link)
Port: N/A (Protocol)

Data link layer protocol commonly used to establish direct connection between network nodes.

Standard
RFC 1661, RFC 1994 (CHAP)
How Used
Provides authentication, encryption, and compression for point-to-point links
Security
PAP, CHAP, EAP authentication protocols
Where Used
  • Dial-up internet connections
  • VPN implementations
  • Serial line communications
  • DSL and cable modems
Example Usage
Dial-up connection: PPP negotiation → authentication (PAP/CHAP) → IP configuration
Key Characteristics
Point-to-point connectivity Authentication support Multiple network protocol support Error detection and correction

OSPF (Open Shortest Path First)

Layer 3 (Network)
Port: N/A (Protocol 89)

Link-state routing protocol that uses Dijkstra's algorithm to find shortest path between nodes.

Standard
RFC 2328 (OSPFv2), RFC 5340 (OSPFv3)
How Used
Routers exchange link-state information to build network topology map
Security
Authentication (simple password, MD5, HMAC-SHA), area design
Where Used
  • Enterprise network routing
  • ISP internal routing
  • Campus network backbones
  • Data center interconnects
Example Usage
Route calculation: LSA flooding → topology database → SPF algorithm → routing table
Key Characteristics
Link-state protocol Hierarchical area design Fast convergence VLSM support

BGP (Border Gateway Protocol)

Layer 3 (Network)
Port: 179

Standardized exterior gateway protocol designed to exchange routing information between autonomous systems.

Standard
RFC 4271, RFC 7606
How Used
Path vector protocol for inter-domain routing with policy-based decisions
Security
BGP authentication, prefix filtering, RPKI validation
Where Used
  • Internet backbone routing
  • ISP interconnections
  • Multi-homed networks
  • Content delivery networks
Example Usage
AS routing: BGP speaker announces prefixes → path attributes → best path selection
Key Characteristics
Path vector protocol Policy-based routing Autonomous system based Internet glue protocol

RIP (Routing Information Protocol)

Layer 3 (Network)
Port: 520

Distance-vector routing protocol that uses hop count as routing metric.

Standard
RFC 1058 (RIPv1), RFC 2453 (RIPv2)
How Used
Routers periodically broadcast routing tables to neighbors
Security
RIPv2 authentication, split horizon, poison reverse
Where Used
  • Small network routing
  • Legacy network compatibility
  • Simple network topologies
  • Educational environments
Example Usage
Route learning: periodic updates every 30 seconds → distance vector algorithm
Key Characteristics
Distance-vector protocol 15 hop limit Periodic updates Simple configuration

EIGRP (Enhanced Interior Gateway Routing Protocol)

Layer 3 (Network)
Port: N/A (Protocol 88)

Cisco proprietary advanced distance-vector routing protocol with fast convergence.

Standard
RFC 7868 (Informational)
How Used
Uses DUAL algorithm for loop-free backup routes and fast convergence
Security
MD5 authentication, neighbor authentication
Where Used
  • Cisco enterprise networks
  • Campus network routing
  • WAN interconnections
  • Hybrid network topologies
Example Usage
Route calculation: feasible successors → DUAL algorithm → topology table
Key Characteristics
Advanced distance-vector Fast convergence Unequal cost load balancing Cisco proprietary

IPSec (Internet Protocol Security)

Layer 3 (Network)
Port: 500 (IKE), 4500 (NAT-T)

Secure network protocol suite that authenticates and encrypts packets of data communicated over IP networks.

Standard
RFC 4301, RFC 4302 (AH), RFC 4303 (ESP)
How Used
Provides authentication and encryption at the IP layer
Security
Strong encryption (AES), authentication (HMAC), integrity protection
Where Used
  • VPN implementations
  • Site-to-site connections
  • Remote access security
  • Cloud network security
Example Usage
VPN tunnel: IKE negotiation → ESP encryption → secure IP packets
Key Characteristics
IP layer security Authentication and encryption Tunnel and transport modes Key management (IKE)

L2TP (Layer 2 Tunneling Protocol)

Layer 5 (Session)
Port: 1701

Tunneling protocol used to support VPNs as part of the delivery of services by ISPs.

Standard
RFC 2661, RFC 3931 (L2TPv3)
How Used
Creates tunnel between L2TP Access Concentrator and L2TP Network Server
Security
Often combined with IPSec for encryption (L2TP/IPSec)
Where Used
  • ISP VPN services
  • Remote access VPNs
  • Mobile device VPNs
  • Wholesale internet services
Example Usage
VPN setup: L2TP tunnel establishment → PPP session → user authentication
Key Characteristics
Layer 2 tunneling UDP-based transport Multiple session support PPP session encapsulation

PPTP (Point-to-Point Tunneling Protocol)

Layer 5 (Session)
Port: 1723

Method for implementing virtual private networks using PPP over IP networks.

Standard
RFC 2637
How Used
Encapsulates PPP packets in IP datagrams for transmission over networks
Security
Weak encryption (deprecated), vulnerable to attacks
Where Used
  • Legacy VPN implementations
  • Windows built-in VPN
  • Simple remote access
  • Small office networks
Example Usage
Remote access: PPTP tunnel → PPP authentication → encrypted session
Key Characteristics
PPP encapsulation Microsoft developed Built into Windows Legacy protocol

GRE (Generic Routing Encapsulation)

Layer 3 (Network)
Port: N/A (Protocol 47)

Tunneling protocol that encapsulates network layer protocols inside virtual point-to-point links.

Standard
RFC 2784, RFC 2890
How Used
Wraps packets in GRE header and outer IP header for tunneling
Security
No built-in encryption, often used with IPSec
Where Used
  • VPN implementations
  • Network tunneling
  • Multicast over WAN
  • Protocol bridging
Example Usage
Site-to-site tunnel: GRE tunnel between routers → encapsulated routing protocols
Key Characteristics
Simple tunneling Multiple protocol support Stateless protocol Recursive tunneling

MPLS (Multiprotocol Label Switching)

Layer 2.5 (Between Data Link and Network)
Port: N/A (Protocol)

Routing technique that directs data from one node to next based on short path labels.

Standard
RFC 3031, RFC 3032
How Used
Uses labels instead of IP addresses for packet forwarding decisions
Security
Inherent isolation, VPN segmentation, traffic engineering
Where Used
  • ISP backbone networks
  • Enterprise WAN services
  • Traffic engineering
  • VPN implementations
Example Usage
Label switching: ingress LSR → label assignment → LSP forwarding → egress LSR
Key Characteristics
Label-based forwarding Quality of Service support Traffic engineering VPN services

VXLAN (Virtual Extensible LAN)

Layer 2 (Data Link)
Port: 4789

Network virtualization technology that uses tunneling to stretch Layer 2 connections over Layer 3 networks.

Standard
RFC 7348
How Used
Encapsulates Layer 2 frames in UDP packets for overlay networks
Security
Isolation through VNI, encryption possible at tunnel level
Where Used
  • Data center virtualization
  • Cloud networking
  • Multi-tenant environments
  • Software-defined networking
Example Usage
Overlay network: VM communication across data centers via VXLAN tunnel
Key Characteristics
Layer 2 overlay 24-bit VNI addressing UDP encapsulation Scalable virtualization

OpenVPN

Layer 7 (Application)
Port: 1194 (default), configurable

Open-source VPN protocol that uses SSL/TLS for encryption and authentication.

Standard
OpenVPN Protocol (proprietary implementation)
How Used
Creates encrypted tunnels using SSL/TLS with certificate-based authentication
Security
Strong SSL/TLS encryption, certificate authentication, perfect forward secrecy
Where Used
  • Remote access VPNs
  • Site-to-site connections
  • Personal privacy VPNs
  • Enterprise security
Example Usage
Secure connection: certificate exchange → TLS handshake → encrypted tunnel
Key Characteristics
SSL/TLS based Cross-platform support Flexible configuration Open source

WireGuard

Layer 3 (Network)
Port: 51820 (default), configurable

Modern VPN protocol designed for simplicity, performance, and strong cryptography.

Standard
RFC 9180 (HPKE), ChaCha20-Poly1305
How Used
Uses state-of-the-art cryptography with minimal code complexity
Security
Modern cryptographic primitives, formal verification, minimal attack surface
Where Used
  • Modern VPN implementations
  • Mobile device VPNs
  • Cloud interconnections
  • Personal privacy networks
Example Usage
Simple setup: public key exchange → UDP tunnel → ChaCha20 encryption
Key Characteristics
Modern cryptography Minimal codebase High performance Simple configuration

RTSP (Real Time Streaming Protocol)

Layer 7 (Application)
Port: 554

Network control protocol for streaming media servers to control streaming media sessions.

Standard
RFC 2326, RFC 7826 (RTSP 2.0)
How Used
Controls streaming sessions with play, pause, seek commands
Security
RTSP over TLS, authentication mechanisms, access control
Where Used
  • IP cameras and surveillance
  • Video streaming servers
  • Live broadcast systems
  • Video conferencing
Example Usage
Video streaming: DESCRIBE → SETUP → PLAY → media delivery → TEARDOWN
Key Characteristics
Session control protocol Media server control Real-time streaming Stateful protocol

RTP (Real-time Transport Protocol)

Layer 4 (Transport)
Port: Dynamic (UDP-based)

Network protocol for delivering audio and video over IP networks in real-time applications.

Standard
RFC 3550, RFC 3551
How Used
Delivers time-sensitive media data with sequence numbers and timestamps
Security
SRTP (Secure RTP) for encryption and authentication
Where Used
  • Voice over IP (VoIP)
  • Video conferencing
  • Live streaming applications
  • Real-time multimedia
Example Usage
VoIP call: RTP audio packets → sequence numbering → jitter buffer → playback
Key Characteristics
Real-time delivery Sequence numbering Timestamp synchronization Quality of Service

SIP (Session Initiation Protocol)

Layer 7 (Application)
Port: 5060 (SIP), 5061 (SIPS)

Signaling protocol used for initiating, maintaining, and terminating real-time sessions.

Standard
RFC 3261, RFC 6665
How Used
Negotiates session parameters and establishes multimedia communications
Security
SIPS (SIP over TLS), authentication, encryption support
Where Used
  • VoIP phone systems
  • Video conferencing setup
  • Instant messaging
  • Presence services
Example Usage
Call setup: INVITE → 180 Ringing → 200 OK → ACK → media session → BYE
Key Characteristics
Session establishment Text-based protocol Stateless design Multimedia support

WebRTC

Layer 7 (Application)
Port: Dynamic (STUN/TURN servers)

Open framework that provides web browsers with real-time communication capabilities.

Standard
RFC 8825, RFC 8826, W3C WebRTC
How Used
Enables direct peer-to-peer communication between web browsers
Security
Mandatory encryption (DTLS/SRTP), identity verification
Where Used
  • Browser-based video calls
  • Web conferencing applications
  • Peer-to-peer file sharing
  • Real-time gaming
Example Usage
Video call: signaling server → ICE candidates → DTLS handshake → encrypted media
Key Characteristics
Browser native support Peer-to-peer communication Real-time media No plugin required

MQTT (Message Queuing Telemetry Transport)

Layer 7 (Application)
Port: 1883 (MQTT), 8883 (MQTTS)

Lightweight messaging protocol designed for small sensors and mobile devices with limited bandwidth.

Standard
ISO/IEC 20922, OASIS MQTT 5.0
How Used
Publish-subscribe messaging model with broker-based architecture
Security
TLS encryption, username/password authentication, client certificates
Where Used
  • IoT device communication
  • Sensor networks
  • Smart home systems
  • Industrial automation
Example Usage
IoT communication: sensor publishes temperature → broker → subscriber receives data
Key Characteristics
Lightweight protocol Publish-subscribe model Quality of Service levels Session persistence

CoAP (Constrained Application Protocol)

Layer 7 (Application)
Port: 5683 (CoAP), 5684 (CoAPS)

Specialized web transfer protocol for constrained nodes and networks in IoT applications.

Standard
RFC 7252, RFC 8323
How Used
RESTful protocol optimized for constrained environments with UDP transport
Security
DTLS encryption, certificate-based authentication
Where Used
  • Constrained IoT devices
  • Sensor networks
  • Machine-to-machine communication
  • Smart city infrastructure
Example Usage
Sensor query: GET coap://sensor.local/temperature → response with sensor data
Key Characteristics
RESTful design UDP-based transport Low overhead Proxy support

LoRaWAN

Layer 1 (Physical)
Port: N/A (Radio protocol)

Low-power wide-area networking protocol designed for wireless IoT devices with long range communication.

Standard
LoRa Alliance Specification
How Used
Star topology with gateways connecting devices to network servers
Security
AES-128 encryption, device and network keys, frame counters
Where Used
  • Smart city infrastructure
  • Agricultural monitoring
  • Asset tracking
  • Environmental sensing
Example Usage
Sensor transmission: device → LoRa gateway → network server → application server
Key Characteristics
Long range communication Low power consumption Star network topology Adaptive data rate

Zigbee

Layer 1 (Physical)
Port: N/A (Radio protocol)

IEEE 802.15.4-based specification for high-level communication protocols used in personal area networks.

Standard
IEEE 802.15.4, Zigbee 3.0
How Used
Mesh networking with coordinator, router, and end device roles
Security
AES-128 encryption, trust center management, key distribution
Where Used
  • Home automation systems
  • Smart lighting control
  • Security systems
  • Industrial monitoring
Example Usage
Smart home: light switch → Zigbee mesh → hub → mobile app control
Key Characteristics
Mesh networking Low power consumption Self-healing network Interoperability

Bluetooth LE

Layer 1 (Physical)
Port: N/A (Radio protocol)

Wireless personal area network technology designed for short-range communication with low energy consumption.

Standard
IEEE 802.15.1, Bluetooth 5.0+
How Used
Short-range radio communication with advertising and connection modes
Security
AES-128 encryption, pairing mechanisms, LE Security Mode
Where Used
  • Wearable devices
  • Fitness trackers
  • Proximity beacons
  • Health monitoring
Example Usage
Fitness tracker: advertise presence → smartphone connects → sync health data
Key Characteristics
Ultra-low power Short range communication Advertising mode GATT services

NFC (Near Field Communication)

Layer 1 (Physical)
Port: N/A (Radio protocol)

Short-range wireless communication technology enabling data exchange between devices in close proximity.

Standard
ISO/IEC 18092, ISO/IEC 14443
How Used
Electromagnetic induction for communication within 4cm range
Security
Secure Element, tokenization, EMV compliance
Where Used
  • Contactless payments
  • Access control systems
  • Device pairing
  • Information sharing
Example Usage
Mobile payment: NFC phone → payment terminal → transaction authorization
Key Characteristics
Very short range (4cm) Passive and active modes Quick connection setup Secure transactions

Wi-Fi 6 (802.11ax)

Layer 1 (Physical)
Port: N/A (Radio protocol)

Latest generation of wireless networking technology providing increased speed and efficiency.

Standard
IEEE 802.11ax
How Used
OFDMA and MU-MIMO technologies for improved efficiency and speed
Security
WPA3 encryption, enhanced authentication, stronger protection
Where Used
  • High-density environments
  • Enterprise networks
  • Smart homes
  • Public Wi-Fi hotspots
Example Usage
Office network: multiple devices simultaneously connected with optimal bandwidth allocation
Key Characteristics
High throughput Improved efficiency Better range Enhanced security

5G NR (New Radio)

Layer 1 (Physical)
Port: N/A (Radio protocol)

Fifth generation cellular network technology providing ultra-fast wireless communication.

Standard
3GPP Release 15/16/17
How Used
Millimeter wave frequencies and massive MIMO for high-speed connectivity
Security
Enhanced encryption, network slicing security, authentication improvements
Where Used
  • Mobile broadband
  • IoT applications
  • Autonomous vehicles
  • Industrial automation
Example Usage
Smart factory: real-time control systems with ultra-low latency 5G connectivity
Key Characteristics
Ultra-high speed Low latency Massive device connectivity Network slicing

HTTP/3

Layer 7 (Application)
Port: 443 (over QUIC)

Third major version of HTTP protocol using QUIC transport for improved performance and security.

Standard
RFC 9114, RFC 9000 (QUIC)
How Used
QUIC transport protocol providing multiplexed streams without head-of-line blocking
Security
Built-in TLS 1.3 encryption, connection migration, improved privacy
Where Used
  • Modern web applications
  • Content delivery networks
  • Real-time web services
  • Mobile web browsing
Example Usage
Fast web loading: QUIC connection → parallel resource loading → improved performance
Key Characteristics
Built on QUIC protocol Multiplexed streams Reduced latency Connection migration

QUIC

Layer 4 (Transport)
Port: 443 (default)

Modern transport protocol providing secure multiplexed connections with reduced latency.

Standard
RFC 9000, RFC 9001, RFC 9002
How Used
UDP-based protocol with built-in TLS encryption and stream multiplexing
Security
Integrated TLS 1.3, connection migration, forward secrecy
Where Used
  • HTTP/3 implementations
  • Real-time applications
  • Content delivery
  • Gaming platforms
Example Usage
Low-latency communication: 0-RTT connection establishment → encrypted streams
Key Characteristics
Built-in encryption Stream multiplexing Connection migration Reduced handshake

DNS over HTTPS (DoH)

Layer 7 (Application)
Port: 443

Protocol for performing remote DNS resolution via HTTPS to improve privacy and security.

Standard
RFC 8484
How Used
Encapsulates DNS queries in HTTPS requests to prevent interception
Security
HTTPS encryption, DNS query privacy, authentication of DNS server
Where Used
  • Privacy-focused browsers
  • Enterprise security
  • Censorship circumvention
  • Mobile applications
Example Usage
Secure DNS: browser → DoH provider (cloudflare.com/dns-query) → encrypted DNS response
Key Characteristics
DNS privacy protection HTTPS encryption Standard web port usage Browser integration

DNS over TLS (DoT)

Layer 7 (Application)
Port: 853

Security protocol for encrypting and wrapping DNS queries and responses via TLS.

Standard
RFC 7858, RFC 8310
How Used
Establishes TLS connection for DNS queries to prevent eavesdropping
Security
TLS encryption, DNS server authentication, query integrity
Where Used
  • Enterprise DNS security
  • ISP privacy protection
  • Mobile device security
  • Network monitoring evasion
Example Usage
Private DNS: client → TLS handshake → encrypted DNS queries → secure responses
Key Characteristics
Dedicated port (853) TLS encryption DNS privacy Certificate validation

mDNS (Multicast DNS)

Layer 7 (Application)
Port: 5353

Protocol that performs DNS-like operations on local network without requiring DNS server.

Standard
RFC 6762
How Used
Uses multicast to resolve hostnames to IP addresses on local network
Security
Local network scope, no authentication by default
Where Used
  • Apple Bonjour services
  • Printer discovery
  • Smart home devices
  • Local service discovery
Example Usage
Service discovery: device broadcasts mDNS query → local devices respond with services
Key Characteristics
Zero-configuration networking Local network resolution Multicast-based Service discovery

SCTP (Stream Control Transmission Protocol)

Layer 4 (Transport)
Port: N/A (Protocol 132)

Transport layer protocol providing reliable, ordered delivery of data with multi-homing support.

Standard
RFC 4960, RFC 3286
How Used
Provides TCP-like reliability with UDP-like message orientation
Security
Built-in protection against blind attacks, four-way handshake
Where Used
  • Telecommunications signaling
  • WebRTC data channels
  • Fault-tolerant applications
  • Multi-homed servers
Example Usage
Telecom signaling: multi-homed connection → stream multiplexing → reliable delivery
Key Characteristics
Multi-streaming Multi-homing support Message-oriented Partial reliability

WebSocket

Layer 7 (Application)
Port: 80 (WS), 443 (WSS)

Communication protocol providing full-duplex communication channels over a single TCP connection.

Standard
RFC 6455
How Used
Upgrades HTTP connection to persistent bidirectional communication
Security
WSS (WebSocket Secure) over TLS, origin validation, authentication
Where Used
  • Real-time web applications
  • Online gaming
  • Live chat systems
  • Financial trading platforms
Example Usage
Live chat: HTTP upgrade → WebSocket handshake → real-time message exchange
Key Characteristics
Full-duplex communication Low latency HTTP-compatible upgrade Real-time messaging

GraphQL

Layer 7 (Application)
Port: 80/443 (HTTP/HTTPS)

Data query and manipulation language for APIs and a runtime for fulfilling queries with existing data.

Standard
GraphQL Specification (Facebook)
How Used
Single endpoint for all data requests with flexible query structure
Security
Authentication middleware, query complexity analysis, rate limiting
Where Used
  • Modern API development
  • Frontend-backend communication
  • Mobile application backends
  • Microservices architecture
Example Usage
API query: query { user(id: 123) { name, email, posts { title } } }
Key Characteristics
Single endpoint Type system Real-time subscriptions Introspection

gRPC

Layer 7 (Application)
Port: 80/443 (HTTP/2)

High-performance RPC framework that uses HTTP/2 for transport and Protocol Buffers as interface description language.

Standard
gRPC Protocol (Google)
How Used
Service definitions in Protocol Buffers with automatic code generation
Security
TLS encryption, authentication plugins, authorization interceptors
Where Used
  • Microservices communication
  • High-performance APIs
  • Cloud-native applications
  • Inter-service communication
Example Usage
RPC call: client.GetUser(UserRequest{id: 123}) → UserResponse
Key Characteristics
HTTP/2 based Protocol Buffers Streaming support Cross-language

AMQP (Advanced Message Queuing Protocol)

Layer 7 (Application)
Port: 5672 (AMQP), 5671 (AMQPS)

Open standard application layer protocol for message-oriented middleware focused on queuing, routing, and security.

Standard
ISO/IEC 19464, AMQP 1.0
How Used
Message broker facilitates reliable message delivery between applications
Security
SASL authentication, TLS encryption, access control mechanisms
Where Used
  • Enterprise messaging systems
  • Microservices communication
  • Event-driven architectures
  • Financial trading systems
Example Usage
Message flow: producer → exchange → queue → consumer with acknowledgments
Key Characteristics
Message queuing Reliable delivery Routing and filtering Transaction support

STOMP (Simple Text Oriented Messaging Protocol)

Layer 7 (Application)
Port: 61613 (default)

Simple text-based protocol for connecting to message brokers and enabling publish-subscribe messaging.

Standard
STOMP Protocol Specification
How Used
Text-based frames for simple message broker communication
Security
Login frames, TLS encryption, broker-level authentication
Where Used
  • Web-based messaging
  • Real-time notifications
  • Chat applications
  • Live data feeds
Example Usage
Message send: SEND\ndestination:/queue/test\n\nHello World
Key Characteristics
Text-based protocol Simple frame structure Message acknowledgment Subscription management

Kafka Protocol

Layer 7 (Application)
Port: 9092 (default)

High-throughput distributed streaming platform protocol for handling real-time data feeds.

Standard
Apache Kafka Protocol
How Used
Topic-based publish-subscribe with distributed partitioning
Security
SASL authentication, SSL encryption, ACL authorization
Where Used
  • Big data streaming
  • Event sourcing systems
  • Log aggregation
  • Real-time analytics
Example Usage
Data streaming: producer → Kafka cluster → consumer groups → real-time processing
Key Characteristics
High throughput Distributed partitioning Data persistence Stream processing

Redis Protocol (RESP)

Layer 7 (Application)
Port: 6379 (default)

Simple protocol used for communication with Redis in-memory data structure store.

Standard
REdis Serialization Protocol
How Used
Simple request-response protocol with data type support
Security
AUTH command, TLS encryption, ACL system (Redis 6+)
Where Used
  • Caching systems
  • Session storage
  • Real-time applications
  • Message queuing
Example Usage
Command: SET key value → Response: +OK
Key Characteristics
Simple text protocol Binary-safe strings Pipelining support Pub/Sub messaging

Memcached Protocol

Layer 7 (Application)
Port: 11211 (default)

Simple protocol for high-performance distributed memory caching system.

Standard
Memcached Protocol
How Used
Key-value storage with simple get/set operations
Security
Limited built-in security, network-level protection
Where Used
  • Web application caching
  • Database query caching
  • Session caching
  • API response caching
Example Usage
Cache operation: set key 0 3600 5\nvalue → STORED
Key Characteristics
Key-value storage LRU eviction Distributed caching Simple protocol

Elasticsearch REST API

Layer 7 (Application)
Port: 9200 (default)

RESTful API protocol for distributed search and analytics engine based on Lucene.

Standard
Elasticsearch REST API
How Used
HTTP REST API for indexing, searching, and analyzing data
Security
X-Pack security, SSL/TLS, role-based access control
Where Used
  • Full-text search
  • Log analysis
  • Business intelligence
  • Application monitoring
Example Usage
Search query: GET /index/_search?q=term → JSON search results
Key Characteristics
RESTful interface JSON-based queries Real-time indexing Distributed architecture

MongoDB Wire Protocol

Layer 7 (Application)
Port: 27017 (default)

Binary protocol for communication between MongoDB drivers and database servers.

Standard
MongoDB Wire Protocol
How Used
Binary protocol for CRUD operations on document collections
Security
Authentication mechanisms, TLS encryption, field-level encryption
Where Used
  • Document databases
  • Content management
  • Real-time applications
  • Big data storage
Example Usage
Query: find({name: 'John'}) → BSON document results
Key Characteristics
Binary protocol BSON data format Document-oriented Replica set support

MySQL Protocol

Layer 7 (Application)
Port: 3306 (default)

Client-server protocol for communication with MySQL relational database management system.

Standard
MySQL Client/Server Protocol
How Used
SQL query execution with client-server communication
Security
SSL encryption, user authentication, privilege system
Where Used
  • Web applications
  • E-commerce platforms
  • Content management systems
  • Data warehousing
Example Usage
Query: SELECT * FROM users WHERE id = 1 → result set
Key Characteristics
SQL-based queries ACID compliance Replication support Storage engines

PostgreSQL Protocol

Layer 7 (Application)
Port: 5432 (default)

Frontend-backend protocol for communication with PostgreSQL object-relational database system.

Standard
PostgreSQL Frontend/Backend Protocol
How Used
Advanced SQL queries with extended data types and functions
Security
SSL encryption, robust authentication, row-level security
Where Used
  • Enterprise applications
  • Data analytics
  • Geospatial applications
  • Financial systems
Example Usage
Query: SELECT json_agg(row_to_json(t)) FROM table t → JSON aggregation
Key Characteristics
Extended SQL support Custom data types MVCC concurrency Extensible architecture

Oracle TNS

Layer 7 (Application)
Port: 1521 (default)

Transparent Network Substrate protocol for Oracle database connectivity and communication.

Standard
Oracle TNS Protocol
How Used
Connection pooling and load balancing for Oracle database access
Security
Advanced Security Option, encryption, authentication
Where Used
  • Enterprise databases
  • Mission-critical applications
  • Data warehousing
  • Financial systems
Example Usage
Connection: TNS listener → service name resolution → database session
Key Characteristics
Connection multiplexing Load balancing Service registration Failover support

Git Protocol

Layer 7 (Application)
Port: 9418 (git://), 22 (SSH), 80/443 (HTTP/S)

Protocol for efficient transfer of git repository data between client and server.

Standard
Git Transfer Protocol
How Used
Efficient transfer of git objects with delta compression
Security
SSH keys, HTTPS authentication, signed commits
Where Used
  • Source code management
  • Software development
  • CI/CD pipelines
  • Collaborative development
Example Usage
Clone: git clone git://github.com/user/repo.git → repository transfer
Key Characteristics
Delta compression Smart protocol Pack file format Distributed version control

Docker Registry API

Layer 7 (Application)
Port: 5000 (default), 443 (Docker Hub)

HTTP API specification for storing and distributing Docker images and other content.

Standard
OCI Distribution Specification
How Used
RESTful API for pushing, pulling, and managing container images
Security
Bearer token authentication, TLS encryption, content trust
Where Used
  • Container image storage
  • CI/CD pipelines
  • Container orchestration
  • Application deployment
Example Usage
Image pull: GET /v2/library/nginx/manifests/latest → image layers
Key Characteristics
RESTful API Layer-based storage Content addressable Manifest format

Kubernetes API

Layer 7 (Application)
Port: 6443 (default), 8080 (insecure)

RESTful API for managing containerized applications in Kubernetes clusters.

Standard
Kubernetes API Server
How Used
Declarative API for managing cluster resources and workloads
Security
RBAC, authentication plugins, admission controllers
Where Used
  • Container orchestration
  • Microservices management
  • Cloud-native applications
  • DevOps automation
Example Usage
Resource creation: POST /api/v1/pods → create pod resource
Key Characteristics
Declarative API Resource-based Watch mechanism Custom resources

XMPP (Extensible Messaging and Presence Protocol)

Layer 7 (Application)
Port: 5222 (client), 5269 (server)

Open standard communication protocol for message-oriented middleware based on XML.

Standard
RFC 6120, RFC 6121, RFC 6122
How Used
XML-based messaging with extensible protocol architecture
Security
SASL authentication, TLS encryption, end-to-end encryption
Where Used
  • Instant messaging
  • Presence information
  • IoT device communication
  • Real-time collaboration
Example Usage
Message: <message to='user@domain'><body>Hello</body></message>
Key Characteristics
XML-based messaging Presence information Extensible protocol Federation support

IRC (Internet Relay Chat)

Layer 7 (Application)
Port: 6667, 6697 (SSL)

Application layer protocol for real-time text messaging and communication in channels.

Standard
RFC 1459, RFC 2810-2813
How Used
Text-based protocol for joining channels and sending messages
Security
SSL/TLS encryption, NickServ authentication, channel modes
Where Used
  • Community chat rooms
  • Developer collaboration
  • Technical support
  • Open source projects
Example Usage
Commands: JOIN #channel, PRIVMSG #channel :Hello everyone
Key Characteristics
Channel-based chat Text-based protocol Server networks User modes and privileges

Matrix Protocol

Layer 7 (Application)
Port: 443 (HTTPS), 8448 (federation)

Open standard for secure, decentralized, real-time communication over IP networks.

Standard
Matrix Specification
How Used
HTTP API with JSON events for federated communication
Security
End-to-end encryption, device verification, cross-signing
Where Used
  • Secure messaging
  • Team collaboration
  • Voice/video calling
  • Bridging other protocols
Example Usage
Message event: PUT /_matrix/client/r0/rooms/!roomid:server/send/m.room.message
Key Characteristics
Decentralized architecture End-to-end encryption Federation support Rich media support