The best way to understand ports and protocols is to:
Go through the process of memorization either through Anki, quizlet, wordwall, or other games
Wrap your head around the concept of what they do. When you know what they do, it will be easier to understand whether they are UDP - Connectionless or TCP - Connection Oriented
Above is a simple offline port game to learn ports and protocols. The key ones are below with UDP important ones at the top
https://wordwall.net/play/18027/795/965
| Protocols UDP only (most important to know they are UDP are the top 4) Acronyms | Name | Port | Use |
|---|---|---|---|
| DNS | Domain Name System | 53 | UDP for queries; Used by the DNS to convert human-readable domain names into IP addresses |
| DHCP | Dynamic Host Configuration Protocol | 67/68 | Server=67 Client=68; |
| TFTP | Trivial File Transfer Protocol | 69 | connectionless protocol for transferring files often used for network device bootstrapping (PXE) or firmware updates |
| SNMP | Simple Network Management Protocol | 161 | Used to allow administrators to monitor and manage network devices |
| NTP | Network Time Protocol | 123 | Low latency protocol used to synchronize timekeeping across a network. This uses a stratum where 0 is the highest and most accurate |
| NetBios | Network Basic Input/Ourput System | 137-139 | Name Resolution and resource sharing on LANs which is a legacy concept basically combining DNS and SMB (TCP) that is port 445 |
| Syslog | System Logging | 514 | A protocol for collecting, sending, and storing log messages from various network devices, applications, and operating systems to a central logging server. Severities are listed where the lowest is the most severe |
| All other Protocols in increased port order | Name | Port | Use |
| FTP | File Transfer Protocol | 20/21 | Sends and receives files between systems |
| SFTP | Secure File Transfer Protocol | 22 | Encrypted file transfers using SSH |
| SSH | Secure Shell | 22 | Encrypted console login |
| Telnet | Telecommunications Network | 23 | Remote console login to network devices that is unsecured (plain text) |
| SMTP | Simple Mail Transfer Protocol | 25 | Transfers email between mail servers |
| HTTP | Hypertext Transfer Protocol | 80 | Web Server Communication |
| LDAP | Lightweight Directory Access Protocol | 389 | Used to store and retrieve information in a network directory like user accounts, groups, policies, and organizational info. Think of it like the phone book of an organization. Often integrated into a centralized system like Active Directory |
| HTTPS | Hypertext Transfer Protocol Secure | 443 | Web server communication with encryption |
| SMB | Server Message Block | 445 | File and Printer Sharing for Windows |
| SMTPS | Simple Mail Transfer Protocol Secure | 587 | Transfer email between mail servers with encryption |
| LDAPS | Lightweight Directory Access Protocol Secure | 636 | Directory Services over SSL/TLS |
| MS-SQL | Microsoft SQL Server | 1433 | Microsoft SQL Database |
| RDP | Remote Desktop Protocol | 3389 | Graphical Display and control of remote Device; aka remoting into a desktop with GUI rather than CLI |
| SIP | Session Initiation Protocol | 5060/5061 | Voice Over IP Signaling Protocol |