FTP
File transfer protocol is an efficient means for transferring files between a computer and an FTP server using FTP client software. FTP client software allows the user to drag and drop files while it produces the necessary
FTP commands associated with the action. It is possible to have an anonymous FTP client by not requiring log in details but generally they require secure logins. FTP is commonly used to update websites on web servers and to
allow rapid data transfer e.g. to upload daily digital film shot on location for digital effects people elsewhere to be able to start working on it.
SSH
SSH is secure shell protocol that lets you log in securely to a remote computer and execute commands. SSH took over from the unencrypted Telnet. SSH uses public key encryption and requires a digital certificate to authenticate
the user. It is widely used by network managers to manage machines remotely. It uses commands similar to MS-DOS.
SSH can be used to make a TCP connection to a remote port for the purpose of sending commands to this port using
application level protocols such as GET for HTTP, SMTP commands for sending email and POP3 for retrieving email. This can be a useful tool to encrypt data travelling between two networks. It can also allow access to services that
might otherwise be blocked by the company firewall.
Email servers
Email servers are like digital mailboxes for your email messages. Outgoing messages are sent using SMTP form your computer to your mail server and from your mail server to the recipients mail server where they are stored.
Incoming email messages can be accessed from your mail server either using POP3 or IMAP.
POP3 downloads the messages from the server to the device you access them on. this means if you accessed them later from a different
device you would not see messages you downloaded earlier. IMAP on the other hand, downloads a copy of a message so the original message remains on your mail server and would be visible if you logged into your email account on
another device.
Web servers
A web server hosts web pages. Users request web pages from web servers using HTTP. Large organisations with lots of visitors may have several duplicates of their site on different web servers to spread the load when they are
busy. Web pages are made up of HTML web pages that are made up of elements in tags, cascading style sheets(CSS) that apply formatting and layout rules to those elements and JavaScript code that adds additional interactivity to
websites.
