Computer Networking and Remote Access

Transport Layer

• Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are protocols used in the Transport Layer.

Transport Layer Addressing (Port Numbers)

• Internet Corporation for Assigned Names and Numbers (ICANN) controls port numbers.
• Well-Known ports: ranges from 0 to 1,023 and are assigned and controlled by ICANN.
• Registered ports: ranges from 1,024 to 49,151, are not assigned or controlled by ICANN, but can be registered to avoid duplication.
• Dynamic ports: ranges from 49,152 to 65,535, are neither controlled nor registered.

Application Layer

• Communication between processes or applications occurs in the Application Layer.
• Examples of internet services:
  • World Wide Web: HTTP
  • Naming Service: DNS
  • File Transfer: FTP
  • Telnet Service
  • Electronic Mail service: IMAP, POP3, SMTP

URL (Universal Resource Locator)

• Consists of Protocol (HTTP, HTTPS, or FTP), Host (domain name of the computer), Port (optional), and Path (pathname of the file).

HTTP (Hyper Text Transfer Protocol)

• Supports the delivery of web pages to the client.

DNS (Domain Name Servers)

• Translates human-readable names into IP addresses.
• Process of getting a website:
  • Check the cache
  • Check the hosts file
  • Ask DNS server

FTP (File Transfer Protocol)

• Provides reliable data transfer between hosts.
• FTP Clients:
  • Internet Browser
  • MS Windows built-in FTP client
  • Third-party programs (e.g., Cute FTP)

Telnet/SSH or RDP

• Telnet/SSH is a user command and an underlying TCP/IP protocol for accessing remote computers.
• Remote Desktop Protocol (RDP) is a Microsoft proprietary protocol for remote connections to other computers.

Mail Server and Clients

• Mail Clients:
  • Web-based: Hotmail, Gmail
  • Non-web-based: Microsoft Outlook
• Mail Protocols:
  • SMTP (send mail transfer Protocol)
  • POP3 (Post Office Protocol version 3)
  • IMAP4 (Internet Message Access Protocol version 4)

Internet of Things (IOT)

• Aims to connect devices to the existing internet infrastructure, enabling "things" to sense and collect data and send it to the internet.
• Examples of devices: coffee maker, air conditioner, washing machine, ceiling fan, lights, etc.
• Practical applications:
  • Smart Homes
  • Smart Cities
  • Energy
  • Environment monitoring
  • Healthcare management