protocol.how|

Interactive network protocol simulator

Explore how different network protocols operate by typing real commands and receieve authentic responses.

Select a protocol below to start experimenting.

SMTP Application Port 25

Simple Mail Transfer Protocol - Used for sending emails

IMAP Application Port 143

Internet Message Access Protocol - Used for retrieving emails

POP3 Application Port 110

Post Office Protocol - Used for downloading emails

SSH Application Port 22

Secure Shell - Used for secure remote access

TELNET Application Port 23

Teletype Network - Basic remote terminal access

FTP Application Port 21

File Transfer Protocol - Used for transferring files

HTTP/1.1 Application Port 80

Hypertext Transfer Protocol - Used for web communication

TCP Transport

Transmission Control Protocol - Reliable connection-oriented transport

Why protocol.how?

Teaching network protocols can be a complex task in an educational setting. ICT Support departments or MSPs lockdown networks, as they should. However, this can come at the expense of students not being able to follow protocols themselves by issuing commands, for example, working through the steps of sending an email using SMTP. That is why I made protocol.how, to be a sandbox where students can experience interacting with protocols directly.

Overview

There are 2 overview windows that can be opened to view content that the protocols can interact with. They can be opened by the buttons at the bottom right of the browser window, or via links you'll find throughout this site.

File System

Two virtual file systems: local and remote. The remote file system can be accessed via FTP, HTTP, TELNET and SSH. The local file system is accessible via FTP.

Both are shared between all protocols that can access them.

Email Client

A mock email client accessible via IMAP, POP3 and SMTP. Contains typical email folders. Emails sent via SMTP appear in the Outbox.

Data is shared between protocols.

Points to note

  • Each protocol simulator responds according to RFC specifications.
  • Emails sent via SMTP are added to the Outbox in the mock email client. No emails are actually sent.
  • FTP supports authenticated and anonymous access. Anonymous users are restricted to /public_ftp.
  • IMAP & POP3 interact with the mock email client.
  • Email overview is for test@protocol.how mailbox.
  • Web content is served from /var/www/html.
  • Browsing away from a protocol and then returning, will result in any authenticated sessions ending.
  • Credentials for any authenticated actions are, Username: user and Password: password.
  • Command history exists for each protocol, press the up and down arrows to navigate through it.
  • If you want to start again with a fresh setup, click the Reset button on any protocol page. Keep in mind that Email and File System data is shared.