Network Protocol Cheat Sheet
This cheat sheet provides a quick reference for common network protocols across different OSI layers.
Common Network Protocols
| Protocol | Full Name | OSI Layer | Port | Description |
|---|---|---|---|---|
| HTTP | Hypertext Transfer Protocol | 7 | 80 | Used for transmitting hypertext on the World Wide Web |
| HTTPS | Hypertext Transfer Protocol Secure | 7 | 443 | Encrypted version of HTTP |
| FTP | File Transfer Protocol | 7 | 21 | Used for transferring files between client and server |
| SMTP | Simple Mail Transfer Protocol | 7 | 25 | Used for sending email |
| DNS | Domain Name System | 7 | 53 | Translates domain names to IP addresses |
| DHCP | Dynamic Host Configuration Protocol | 7 | 67/68 | Automatically assigns IP addresses to devices on a network |
| Telnet | Telnet | 7 | 23 | Used for remote login (insecure, replaced by SSH) |
| SSH | Secure Shell | 7 | 22 | Encrypted remote login and command execution |
| SNMP | Simple Network Management Protocol | 7 | 161/162 | Used for network device management |
| TLS/SSL | Transport Layer Security/Secure Sockets Layer | 6 | N/A | Provides communication security over a network |
| TCP | Transmission Control Protocol | 4 | N/A | Connection-oriented, reliable data transfer |
| UDP | User Datagram Protocol | 4 | N/A | Connectionless, fast but unreliable data transfer |
| ICMP | Internet Control Message Protocol | 3 | N/A | Used for error reporting and network diagnostics |
| IP | Internet Protocol | 3 | N/A | Delivers packets from source to destination |
| ARP | Address Resolution Protocol | 2 | N/A | Maps IP addresses to MAC addresses |
Understanding Network Protocols
Network protocols are standardized rules that allow devices to communicate with each other. They define how data is packaged, addressed, transmitted, routed, and received.
Key Points:
- Protocols operate at different layers of the OSI model.
- Some protocols use specific port numbers for communication.
- Understanding protocols is crucial for network troubleshooting and security.
- Many application layer protocols have secure versions (e.g., HTTP vs HTTPS).
- Lower layer protocols (like TCP, IP) form the foundation for higher layer protocols.