Lecture on Network Port Numbers and Protocols

Introduction

• Services use port numbers for communication.
• Known as "well-known port numbers."
• Important for:
  • Server and client communication
  • Firewall traffic filtering
• Understanding port numbers aids in memorization and protocol use.

File Transfer Protocol (FTP)

• Transfers files between devices.
• Ports:
  • TCP Port 20: Data transfers
  • TCP Port 21: Control data transfer
• Requires authentication (username/password).
• Allows file management operations (list, add, delete, rename).

Secure Shell (SSH)

• Provides terminal connection to remote devices.
• Port: TCP Port 22
• Encrypted communication (secure shell).

Telnet

• Provides text-based front-end to remote devices.
• Port: TCP Port 23
• Sends data in clear text (non-encrypted).
• Not recommended for use on production networks.

Email Protocols

• Simple Mail Transfer Protocol (SMTP)
  • Communication between email servers.
  • Port: TCP Port 25
• Post Office Protocol Version 3 (POP3)
  • Receives email messages.
  • Port: TCP Port 110
  • Not built for multiple clients.
• Internet Message Access Protocol Version 4 (IMAP4)
  • Synchronizes mail across devices.
  • Port: TCP Port 143

Domain Name System (DNS)

• Resolves domain names to IP addresses.
• Port: UDP Port 53
• Critical for accessing websites without knowing IP addresses.

Dynamic Host Configuration Protocol (DHCP)

• Assigns IP addresses automatically.
• Ports:
  • UDP Port 67
  • UDP Port 68
• Uses IP leasing system.
• DHCP reservations for consistent IP addresses.

Hypertext Transfer Protocol (HTTP) and HTTP Secure (HTTPS)

• HTTP:
  • Non-encrypted web communication.
  • Port: TCP Port 80
• HTTPS:
  • Encrypted web communication.
  • Port: TCP Port 443

Server Message Block (SMB)

• Transfers files and sends print jobs in Windows.
• Ports:
  • UDP Port 137: Name service
  • TCP Port 139: Session service
  • TCP Port 445: Direct SMB communication

Simple Network Management Protocol (SNMP)

• Manages network devices and queries performance metrics.
• Ports:
  • UDP Port 161: Queries
  • UDP Port 162: Traps (alerts)
• Versions:
  • SNMP v1: Non-encrypted
  • SNMP v2: Bulk transfers, non-encrypted
  • SNMP v3: Encrypted, secure

Lightweight Directory Access Protocol (LDAP)

• Queries directories on networks.
• Port: TCP Port 389
• Commonly used with Microsoft Active Directory.

Remote Desktop Protocol (RDP)

• Provides remote desktop access.
• Port: TCP Port 3389
• Used primarily on Windows but available on other OS with clients.

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These notes cover key points about various network protocols and their associated port numbers, useful for understanding and configuring network communications.