Application Layer Protocols – Deep dive

Some of the most popular protocols on the internet that are often used especially in a Software as a Service (SaaS) delivery model. Note that many of these protocols are used across different layers of the TCP/IP model.

  1. HTTP (Hypertext Transfer Protocol): The protocol used by web browsers to fetch web pages from servers.
  2. HTTPS (Hypertext Transfer Protocol Secure): Secure version of HTTP, encrypts communication between client and server.
  3. FTP (File Transfer Protocol): Used to transfer files between client and server.
  4. SSH (Secure Shell): Used for secure remote server administration.
  5. SMTP (Simple Mail Transfer Protocol): Used to send email messages between servers, and sending emails from client to server.
  6. IMAP (Internet Message Access Protocol): Used to fetch email messages from a server.
  7. POP3 (Post Office Protocol 3): An alternative protocol to IMAP, used to fetch emails from a server.
  8. TLS (Transport Layer Security): A cryptographic protocol used to secure communication over a network.
  9. SIP (Session Initiation Protocol): A signalling protocol for initiating, maintaining, modifying and terminating real-time sessions that involve video, voice, messaging and other communications applications and services between two or more endpoints on IP networks.
  10. XMPP (Extensible Messaging and Presence Protocol): A communication protocol for message-oriented middleware based on XML.
  11. LDAP (Lightweight Directory Access Protocol): Used to access and maintain distributed directory information services over an IP network.
  12. RDP (Remote Desktop Protocol): A proprietary protocol developed by Microsoft, which provides a user with a graphical interface to connect to another computer over a network connection.
  13. DNS (Domain Name System): Used for domain name resolution, translating human-readable URLs into IP addresses.
  14. DHCP (Dynamic Host Configuration Protocol): Assigns IP addresses to devices on a network.
  15. TCP (Transmission Control Protocol): Provides reliable, ordered, and error-checked delivery of a stream of bytes between applications running on hosts communicating via an IP network.
  16. UDP (User Datagram Protocol): A simple message-oriented transport layer protocol that is documented in RFC 768.
  17. ICMP (Internet Control Message Protocol): Used by network devices, like routers, to send error messages and operational information.
  18. SNMP (Simple Network Management Protocol): Collects and organises information about managed devices on IP networks and modifies that information to change device behavior.
  19. SSL (Secure Sockets Layer): Encrypts communication between web browsers and servers.
  20. SFTP (SSH File Transfer Protocol): A secure file transfer protocol.
  21. RADIUS (Remote Authentication Dial-In User Service): A networking protocol, operating on port 1812 that provides centralised Authentication, Authorisation, and Accounting (AAA or Triple A) management for users who connect and use a network service.
  22. SOAP (Simple Object Access Protocol): A protocol which is used for exchanging structured information in the implementation of web services in computer networks.
  23. REST (Representational State Transfer): A software architectural style that defines a set of constraints to be used for creating web services.
  24. JSON-RPC and XML-RPC (Remote Procedure Call): A remote procedure call (RPC) protocol encoded in JSON or XML.
  25. WebRTC (Web Real-Time Communication): A protocol for rich, high-quality RTC applications to be developed for the browser, mobile platforms, and IoT devices, and allow them all to communicate via a common set of protocols.
  26. IPsec (Internet Protocol Security): A protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session.
  27. OAuth (Open Authorization Protocol): An open standard for access delegation, commonly used as a way for Internet users to grant websites or applications access to their information on other websites but without giving them the passwords.
  28. SAML (Security Assertion Markup Language): An open standard for exchanging authentication and authorisation data between parties, in particular, between an identity provider and a service provider.
  29. OpenID Connect: A simple identity layer on top of the OAuth 2.0 protocol, which allows computing clients to verify the identity of an end-user based on the authentication performed by an authorization server, as well as to obtain basic profile information about the end-user.
  30. MQTT (Message Queuing Telemetry Transport): A lightweight messaging protocol for small sensors and mobile devices, optimized for high-latency or unreliable networks.

For deeper exploration, each of the protocol names is linked to their respective RFCs or documentation. Some protocols like OpenID Connect, SAML, SOAP, and REST do not have RFCs but rather have detailed specifications provided by other organisations or standards bodies.