9.4.2 Application Layer Protocols (FTP (Some FTP clients are built-in…
9.4.2 Application Layer Protocols
Some FTP clients are built-in components within other programs that allow you to transfer files to and from a specified remote server through a special FTP panel. For example, Dreamweaver’s Files panel can be used as an FTP tool. When you expand the Files panel, you can even see both the remote and local views of the files being transferred and can transfer files in either direction.
FTP Server: non-anonymous eg online shopping - the user must sign in before they can purchase goods.
File Transfer Protocol: the set of rules for downloading/uploading files over TCP/IP networks, including the Internet
Example: web developer uploading new web pages to the host server for their website
Anonymous - the FTP server can be configured so that a user does not have to log in. These servers should only host public files as they are less secure than non-anonymous.
HTTP & HTTPS
Post Office Protocol:
Used by e-mail clients to retrieve e-mail from a
server in an Internet Protocol (IP) network
A POP3 mail server receives e-mails and filters them into the appropriate user folders. When a user connects to the mail server to retrieve mail, the messages are downloaded from mail server to the user's hard disk.
Most mail servers use the POP3 mail protocol because it is simple and well-supported.
Simple Mail Transfer Protocol
Email software most commonly uses SMTP for sending emails
SMTP runs on top of TCP/IP and uses TCP port number 25 for standard communication.
Secure Shell: a software package that enables secure system administration and file transfers over insecure networks. It is used in nearly every data center, in every larger enterprise.
Used to make a TCP connection to a remote port so that commands can be sent to this port using App protocols such as GET for HTTP, SMTP commands for sending email and POP3 to retrieve email
Log in securely to a remote computer and execute commands
Great section on the history of this protocol &
Client/Server Diagram, using public key encryption
Retrieving email - POP3
Sending email - SMTP
An outgoing server
Stores incoming mail for distribution to local
users and sends out outgoing messages.
Web pages in text form
Process incoming network requests
over the HTTP protocol
Stores, processes and delivers web pages to clients
A full implementation of HTTP also includes
ways of receiving content from clients.
This feature is used for submitting web forms,
including uploading of files.
Retrieving and rendering
web pages and web resources.
Initiates communication by making a request for a specific resource using HTTP and the server responds with the content of that resource or an error message.
HTML (Hypertext Markup Language) is the set of markup symbols or codes inserted in a file intended for display on a World Wide Web browser page. The markup tells the Web browser how to display a Web page's words and images.