Common Protocols
Overview
Protocols are the rulebooks devices follow to communicate — recognizing them by name and port is essential for reading logs and traffic later in the roadmap.
Key concepts
- DNS, DHCP
- HTTP vs HTTPS
- FTP vs SFTP, SSH
- SMTP, IMAP, POP3
- NTP
How it works
A protocol is a set of rules devices follow to communicate over a network — handling websites, name resolution, address assignment, remote access, email, file transfers, and time sync.
| Protocol | Full name | What it does |
|---|---|---|
| DNS | Domain Name System | Translates domain names into IP addresses. |
| DHCP | Dynamic Host Configuration Protocol | Automatically provides devices with network settings. |
| HTTP | Hypertext Transfer Protocol | Transfers website content between browsers and servers — unencrypted. |
| HTTPS | HTTP Secure | Encrypted HTTP, using TLS to protect transmitted data. |
| FTP | File Transfer Protocol | Transfers files between systems — traditional FTP does not encrypt credentials or data. |
| SFTP | SSH File Transfer Protocol | Transfers files securely through an SSH connection. |
| SSH | Secure Shell | Encrypted protocol for remotely accessing and managing systems. |
| SMTP | Simple Mail Transfer Protocol | Sends email between email systems. |
| IMAP | Internet Message Access Protocol | Lets an email client access/sync messages stored on a server. |
| POP3 | Post Office Protocol v3 | Downloads messages from an email server to a local device. |
| NTP | Network Time Protocol | Synchronizes time across network devices — correct time matters for logs, authentication, certificates, and incident response. |