[Day 4] 3. Protocols

HTTP/HTTPS

• HTTP (Hypertext Transfer Protocol): Port 80, used for transferring web data.
• HTTPS (HTTP Secure): Port 443, encrypted communication for security.

FTP/TFTP

• FTP (File Transfer Protocol): Reliable, uses TCP, allows directory browsing, and requires authentication. Typically uses port 21 for command/control and port 20 for data transfer.
• TFTP (Trivial FTP): Fast but less secure, uses UDP, and does not require authentication. Uses port 69.

SMTP, POP3, IMAP

• SMTP (Simple Mail Transfer Protocol): Used to send emails (push protocol).
• POP3 (Post Office Protocol): Retrieves emails (pull protocol).
• IMAP (Internet Message Access Protocol): Combines both push and pull functionalities and is optimized for modern email services.

Telnet

• A protocol used to remotely access network devices over a command-line interface. It’s less secure compared to modern alternatives like SSH. Telnet uses port 23 while SSH uses port 22.

SNMP (Simple Network Management Protocol)

• Used for network management and monitoring. It collects information via traps and alerts, which help administrators manage network performance.
• Typically uses port 161 for SNMP messages and port 162 for SNMP trap messages.

DNS (Domain Name System)

• Resolves domain names to IP addresses. Uses both UDP (for faster lookups) and TCP (for reliability when necessary).
• Uses port 53.

DHCP (Dynamic Host Configuration Protocol)

• Automatically assigns IP addresses to devices in a network. DHCP assigns:
  • IP address
  • Subnet mask
  • Default gateway
  • DNS server addresses
• Port 67: This is the server port used by the DHCP server to listen for client requests.
• Port 68: This is the client port used by DHCP clients to send requests to the server.