Connecting to a server requires knowledge of the port number of the service running on that device, commonly referred to as well-known port numbers.
This understanding is crucial for configuring firewall rules, which involve adding an IP address and a corresponding port number to control traffic.
Memorization of port numbers may initially seem like rote memorization, but practical experience improves retention.
Purpose: Used for transferring files and managing file systems.
Port Numbers:
TCP Port 20: Active mode data transfer.
TCP Port 21: Control connection for FTP commands.
Authentication: Often uses username and password; some servers allow anonymous logins.
Capabilities: List, add, and delete files and folders on the server.
Purpose: Provides secure access to the command line of a remote device.
Port Number: TCP Port 22.
Features: Encrypted communication, making it secure compared to Telnet.
Purpose: Provides console or terminal access to devices using a text-based interface.
Port Number: TCP Port 23.
Security Note: Unencrypted communications make it insecure; prefer SSH when possible.
Purpose: Used to send emails between devices.
Port Number: TCP Port 25.
Functionality: Sends mail from client to mail server and between mail servers.
Purpose: Converts fully qualified domain names into IP addresses.
Port Number: UDP Port 53.
Purpose: Automatically assigns IP addresses and other network configuration settings to devices.
Port Numbers:
UDP Port 67: Server-side.
UDP Port 68: Client-side.
Functionality: Provides real-time IP address assignments with a lease time; supports IP address reservations based on MAC addresses.
HTTP (Hypertext Transfer Protocol)
Purpose: Used for web browsing, transmitting data between client and web server.
Port Number: TCP Port 80.
HTTPS (HTTP Secure)
Purpose: Secure version of HTTP with encrypted data transmission.
Port Number: TCP Port 443.
POP3 (Post Office Protocol version 3)
Purpose: Retrieves emails from a server.
Port Number: TCP Port 110.
Limitation: Lacks synchronization capabilities across multiple devices.
IMAP (Internet Message Access Protocol version 4)
Purpose: Retrieves and synchronizes emails across devices.
Port Number: TCP Port 143.
Purpose: Protocol for file and printer sharing, primarily associated with Windows.
Port Numbers:
TCP Port 445: Direct SMB over IP.
Legacy usage of NetBIOS now rarely implemented (UDP Port 137, TCP Port 139).
Purpose: Monitors and manages network devices.
Port Numbers:
UDP Port 161: Queries for device performance data.
UDP Port 162: SNMP traps for proactive device monitoring.
Versions:
SNMPv1: Basic single queries, no security.
SNMPv2: Bulk data transfer, still unsecured.
SNMPv3: Enhanced security with encryption.
Purpose: Accesses directory services like Microsoft Active Directory.
Port Number: TCP Port 389.
Purpose: Provides remote desktop access to Windows machines.
Port Number: TCP Port 3389.
Functionality: Allows full control of the desktop or access to specific applications; supports various operating systems as RDP clients.
2.1 Common Network Ports - CompTia A+ 220-1101
Connecting to a server requires knowledge of the port number of the service running on that device, commonly referred to as well-known port numbers.
This understanding is crucial for configuring firewall rules, which involve adding an IP address and a corresponding port number to control traffic.
Memorization of port numbers may initially seem like rote memorization, but practical experience improves retention.
Purpose: Used for transferring files and managing file systems.
Port Numbers:
TCP Port 20: Active mode data transfer.
TCP Port 21: Control connection for FTP commands.
Authentication: Often uses username and password; some servers allow anonymous logins.
Capabilities: List, add, and delete files and folders on the server.
Purpose: Provides secure access to the command line of a remote device.
Port Number: TCP Port 22.
Features: Encrypted communication, making it secure compared to Telnet.
Purpose: Provides console or terminal access to devices using a text-based interface.
Port Number: TCP Port 23.
Security Note: Unencrypted communications make it insecure; prefer SSH when possible.
Purpose: Used to send emails between devices.
Port Number: TCP Port 25.
Functionality: Sends mail from client to mail server and between mail servers.
Purpose: Converts fully qualified domain names into IP addresses.
Port Number: UDP Port 53.
Purpose: Automatically assigns IP addresses and other network configuration settings to devices.
Port Numbers:
UDP Port 67: Server-side.
UDP Port 68: Client-side.
Functionality: Provides real-time IP address assignments with a lease time; supports IP address reservations based on MAC addresses.
HTTP (Hypertext Transfer Protocol)
Purpose: Used for web browsing, transmitting data between client and web server.
Port Number: TCP Port 80.
HTTPS (HTTP Secure)
Purpose: Secure version of HTTP with encrypted data transmission.
Port Number: TCP Port 443.
POP3 (Post Office Protocol version 3)
Purpose: Retrieves emails from a server.
Port Number: TCP Port 110.
Limitation: Lacks synchronization capabilities across multiple devices.
IMAP (Internet Message Access Protocol version 4)
Purpose: Retrieves and synchronizes emails across devices.
Port Number: TCP Port 143.
Purpose: Protocol for file and printer sharing, primarily associated with Windows.
Port Numbers:
TCP Port 445: Direct SMB over IP.
Legacy usage of NetBIOS now rarely implemented (UDP Port 137, TCP Port 139).
Purpose: Monitors and manages network devices.
Port Numbers:
UDP Port 161: Queries for device performance data.
UDP Port 162: SNMP traps for proactive device monitoring.
Versions:
SNMPv1: Basic single queries, no security.
SNMPv2: Bulk data transfer, still unsecured.
SNMPv3: Enhanced security with encryption.
Purpose: Accesses directory services like Microsoft Active Directory.
Port Number: TCP Port 389.
Purpose: Provides remote desktop access to Windows machines.
Port Number: TCP Port 3389.
Functionality: Allows full control of the desktop or access to specific applications; supports various operating systems as RDP clients.