CHAPTER SIX: SUPPORTING NETWORK SERVICES Flashcards
(56 cards)
Define server
The server is the computer that holds files or manages the printer.
Define client
The client is any other computer on the network trying to access those files or use the printer.
Define fileshare
When a file is made available over the network, it’s called a fileshare. These servers use a client/server architecture—one computer (server) provides, the others (clients) use.
- Sometimes, special software like File and Print Services for Windows Networks is used.
- Another way to share files is using FTP (File Transfer Protocol)
Server Message Block (SMB)
This is the language (called a protocol) that Windows computers use to talk to each other for file and printer sharing. SMB runs over the internet using something called TCP port 445 (think of this like a numbered doorway into a computer).
The latest version is SMB3—faster and more secure.
Older version SMB1 is outdated and has major security problems, so it’s usually turned off on modern Windows systems.
Define NetBIOS
Back in the early days, before the internet as we know it, Windows used something called NetBIOS to let computers recognize each other by name (like calling someone by their nickname). NetBIOS worked before the internet-standard TCP/IP was popular. Later, they created NetBT (NetBIOS over TCP/IP) so it could work over modern networks.
Today, NetBT is old and risky—only turn it on if you’re dealing with super old Windows systems (before Windows 2000).
File Transfer Protocol (FTP)
FTP is like using a mail service between computers—you send or receive files through it.
Uses TCP port 21 to start the conversation between client and server.
It can use port 20 (active mode) or other ports (passive mode) to actually transfer the files.
Commonly used to upload stuff to websites.
Web Servers
A Web Server is a computer that “serves” websites to users. Uses the HTTP (or secure version HTTPS) protocol to send web pages to your browser.
When you type in a website, your browser (the client) asks the web server to give it the page content.
Web servers can be used for public websites or private company pages called intranets (only for insiders) or extranets (for outside partners with permission).
Hypertext Transfer Protocol (HTTP)
HTTP is the set of rules web browsers and servers follow to exchange web pages.
Runs over TCP port 80 (or 443 for secure HTTPS).
Your browser sends a request like “GET this page.”
The server responds with the page or an error if it’s not there.
Hypertext Markup Language (HTML), Forms, and Web Applications
HTML is the coding language that web pages are written in.
It tells the browser how to display text, images, videos, and links.
Web pages often contain hyperlinks—clickable links to other pages.
Pages can also include forms so users can send information (like typing into a contact form and clicking submit).
Many modern sites are web applications—they act like programs (think: Gmail or Facebook).
Uniform Resource Locator (URL)
A URL is the full address for a website or file online.
It breaks down like this:
1. https = the protocol (how you’re connecting)
2. www.example.com = the host location (can be a domain name or IP address)
3. /folder/page.html = the file path (location of the file on the server)
Web Server Deployment
To have a website, you need a place to host it:
Small businesses may rent space on a web server from an Internet Service Provider (ISP).
Big companies might run their own servers in data centers.
Some web servers are only used internally (intranets) or for authorized outside users (extranets), not for the public internet.
Hypertext Transfer Protocol Secure (HTTPS)
Back in the early days of the internet, websites used something called HTTP to show pages. The problem? HTTP sent everything (like passwords or messages) in plain text — anyone watching could see it! To fix that, a company called Netscape made something called SSL (Secure Sockets Layer) in the 1990s. It made your data private by scrambling it up (encryption).
Later, TLS (Transport Layer Security) came along as the new and improved version of SSL. When TLS is used with HTTP, it becomes HTTPS — the “S” means it’s secure.
When your browser connects to an HTTPS website:
It uses port 443 (instead of port 80, which is used for insecure HTTP).
The website has a digital certificate from a Certificate Authority (CA), a trusted company that says, “Yes, this website is legit.”
The website uses encryption keys — one public key (shared with everyone) and one private key (kept secret).
Your browser uses the public key to safely create an encrypted tunnel.
Only the server with the private key can understand the tunnel data — this keeps hackers out.
Simple Mail Transfer Protocol (SMTP)
When you send an email, something called the Simple Mail Transfer Protocol (SMTP) handles delivery. Think of SMTP as the mail truck that gets your message from your email provider to the other person’s provider.
Here’s how it works:
Your email app gives the message to an SMTP server.
That server looks up the IP address of the receiver’s email server using DNS records like MX (Mail Exchange).
It then delivers the message to that server.
There are a couple of different ports with SMTP
Port 25: for sending email between servers. Not secure.
Port 587: for sending email from your email app. It should use encryption to protect your password and message.
Receiving Email
Once the mail gets delivered, it sits on a mailbox server until the recipient checks it. To get that email from the mailbox server, we use mailbox access protocols, like:
POP3 (Post Office Protocol version 3)
IMAP (Internet Message Access Protocol)
POP3 (Post Office Protocol version 3)
Downloads emails to your computer.
Usually deletes them from the server afterward.
Uses port 110 (not secure) or 995 for secure connections
IMAP (Internet Message Access Protocol)
Keeps emails on the server.
Lets you view them on multiple devices.
Lets you organize messages in folders, delete them later, etc.
Uses port 143 (unsecure) or 993 for secure (IMAPS) connections.
What’s Authentication?
Before a device (like your laptop) can access important stuff on a network — like files, email, etc. — it must prove who it is. This is called authentication.
What’s a Directory Server?
A directory server is like a digital phone book with a list of users and passwords. It helps decide who’s allowed to do what on a network.
Big companies use systems like Active Directory (Microsoft) or OpenLDAP (open source).
They use something called LDAP (Lightweight Directory Access Protocol) to look up or change user info in the directory.
LDAP runs over port 389, and can be made secure using encryption.
Authentication, Authorization, and Accounting (AAA)
This is a system to manage who can connect, what they can do, and track what they did. It has three main parts:
Authentication – Prove who you are.
Authorization – What you’re allowed to do.
Accounting – Track what you did.
Here’s how it works:
The device you’re using (the supplicant) asks to join the network.
The network gear (like a Wi-Fi access point or switch) is called a NAS or NAP (network access server/point).
That gear checks with a central AAA server — a brain in the network — to see if you’re allowed.
Instead of storing passwords in each switch or access point (risky and inefficient), these devices forward your credentials to the AAA server, which handles it all.
RADIUS
a popular protocol used to make this AAA system work.
Remote Terminal Access Servers
Think of a remote terminal server like a way to control your computer from far away using just a keyboard screen — like teleporting into your computer and using the command line (text commands) from another location.
terminal
A terminal was originally a physical keyboard and screen (like a typewriter, called a TTY) that connected to a big computer.
Today, we use terminal emulator software to do the same thing on modern computers. It just shows you a command window (black screen, white text).
