COMMOM NETWORK PROTOCOLS
Essentail Network Protocols:
The following protocols are considered essential knowledge for developers, network engineers, and ethical hackers. Mastery of these protocols is fundamental for building, securing and Troubleshooting modern networks. (Click a card to learn more about each protocol)
Core Application Layer Protocols
File Transfer Protocol: Used for transferring files between client and server.
- Function: An old protocol for transferring files. Uses separate channels for commands and data.
- Security: Insecure; sends credentials and data in plaintext. Avoid in favor for SFTP.
Secure File Transfer Protocol: FTP over SSH for secure file transfer.
- Function: A secure protocol for file transfer that runs over an SSH session.
- Security: Inherits the strong encryption and authentiation of SSH, making it the industry standard.
Trivial File Transfer Protocol: Simple, unsecured file transfer protocol.
- Function: A simplified, lightweight file transfer protocol with no authentiation.
- Security: None. Use only on trusted, isolated networks for tasks like device booting.
Secure Shell: Secure remote login and command execution.
- Function: The standard for secure remote command-line access and administration.
- Security: Provides a fully encrypted channel, protecting against eavesdropping and hijacking.
Teletype Network: Unsecure remote login and command execution.
- Function: An early protocol for remote command-line access.
- Security: Completely insecure; sends all data, including passwords, in plaintext. Deprecated.
Simple Mail Transfer Protocol: Used for sending emails.
- Function: The standard for sending email between servers and from a client to a server.
- Security: Use Port 587 with STARTTLS encryption for secure client submission.
Post Office Protocol v3: Receiving emails by downloading them from the server.
- Function: An older protocol used to retrieve email from a server, typically by downloading messages to a single device and then deleting them from the server.
- Security: Inherently insecure as it transmits data in plaintext.
POP3 over SSL: Secure POP3 for email retrieval.
- Function: Used to retrieve email by downloading it from the server, often deleting the server copy.
- Security: Use Port 995 (POP3S) for an encrypted connection.
Internet Message Access Protocol: Accessing emails directly on the server.
- Function: A modern protocol used to access and manage email directly on the server. This allow for state to be synchronized across multiple devices.
- Security: Unencrypted in its base form.
IMAP over SSL: Secure IMAP for email access.
- Function: The secure version of IMAP. It wrap the entire communication in a TLS/SSL encrypted layer.
- Security: The standard for secure, multi-device email access, ensuring confidentaility.
Hypertext Transfer Protocol: Unsecure web browsing.
- Function: The original protocol for web browsing. It follows a simple request-response model.
- Security: Unencrypted; all data is sent in plaintext and is insecure.
Hypertext Transfer Protocol Secure: Secure web browsing with Secure Sockets Layer (SSL) or TLS.
- Function: The secure standard for the web. It is HTTP layered over a TLS/SSL encrypted connection.
- Security: Provides confidentaility, integrity and authentiation. Essentail for all modern sites.
Domain Name System: Used for resolving domain names to IP addresses.
- Function: Translates human-friendly domain names (e.g., example.com) into I addresses.
- Security: Traditional DNS is unencrypted. DNS-over-HTTPS (DoH) adds a layer of privacy.
Dynamic Host Configuration Protocol: Used to assign IP addresses automatically.
- Function: Automatically assigns IP addresses and network settings to devices on a network.
- Security: Has no native authentication; can be vulnerable to rogue servers on a local network.
Network Time Protocol: Synchronizing clocks over a network.
- Function: Synchronized computer clocks across a network, which is critical for logging and security.
- Security: Can be vulnerable to spoofing; use trusted time sources.
Lighweight Directory Access Protocol: Accessing and managing directory information.
- Function: A protocol for querying and modifying information in a directory service (e.g., Active Directory)
- Security: Use Port 636 (LDAPS) for an encrypted connection.
LDAL over SSL: Used for secure LDAP access.
- Function: The secure version of LDAP, used for accessing and maintaining directory services.
- Security: It encrypts all LDAP communication with TLS/SSL, protecting user credentials and directory data.
Simple Network Management Protocol: Used for network management and monitoring.
- Function: Used to monitor and manage network devices like routers and switches.
- Security: Use SNMPv3, as older versions are insecure.
System Logging: Network event logging system and protocol.
- Function: A standard for sending event log messages from devices to a central logging server.
- Security: Basic Syslog in unencrypted; secure variants exist that use TLS.
Server Message Block: File sharing and network communication.
- Function: Used for sharing files, printers, and other resources, primarily on Windows networks.
- Security: Historically vulnerable; requires strict access controls and timely patching.
Structured Query Language(SQL) Server: Database management system by Microsoft.
- Function: The protocol for communicating with Microsoft's SQL Server database.
- Security: Tthe connection should be encrypted to protect data in transit.
SQLNet (Oracle Network Service): Enable Oracle SQL clients to communicate with Oracle database server.
- Function: The protocol used by Oracle databases to facilitate communication between clients and the server.
- Security: Supports network encryption to protect database queries and results.
MySQL: MySQL database service.
- Function: The protocol for communicating with MySQL and MariaDB database systems.
- Security: Supports SSL/TLS to encrypt the connection between the application and database.
Remote Desktop Protocol: Remote desktop access.
- Function: Provides a graphical user interface for remotely accessing another computer.
- Security: A frequent target for attacks. Must be secured with strong passwords and network-level authentication (NLA), preferably behind a VPN.
Session Initiation Protocol: Used for managing multimedia communication sessions
- Function: Used to initiate, maintain, and terminate real-time communication sessions like VoIP calls.
- Security: Use Port 5061 with TLS for encrypted signaling.
Core Network Layer Protocols
- IP (Internet Protocol): Delivers packets across networks; foundation for all internet communications.
- ICMP (Internet Control Message Protocol): Used for sending error and status messages (e.g., ping, traceroute).
- DHCP (Dynamic Host Configuration Protocol): Dynamically assigns IP addresses on a network.
- ARP (Address Resolution Protocol): Resolves IP addresses to MAC addresses in local networks.
Security & Modern Enhancements
| Protocol | Description |
|---|---|
| TLS/SSL | Cryptography for secure sessions (HTTPS, email, VPNs). |
| QUIC/HTTP3 | Next-gen web protocol for high speed, secure communication. |
| Zero Trust (ZTNA) | Framework, not a protocol, but increasingly vital for secure access control and segmentation in distributed networks. |
Why These Protocols Are Essential
- Web Development: HTTP/HTTPS, DNS, TCP/UDP fundamentals.
- Networking: Mastery of IP, DHCP, SNMP, RDP critical for network operations.
- Security/Ethical Hacking: SSH/SFTP (secure remote access), HTTPS/TLS (encryption), SNMP/LDAP (device management), and understanding protocol-specific vulnerabilities.
- Cloud/IoT: Protocols like QUIC, MQTT, and Matter (for IoT) are rising in importance, but the ones above form the baseline.
Quick Reference: Essentails for Every Role
- Developers: HTTP, HTTPS, TCP, UDP, SMTP, DNS, EMAP
- Network Engineers: TCP, UDP, IP, SNMP, DHCP, ARP, OSPF, BGP
- Ethical Hacker: FTP, SMB, SNMP, Telnet, SSH, ICMP, RDP
Solid foundational knowledge of these protocols is vital for effective troubleshooting, building secure systems, and progressing in networking or cybersecurity careers