A communication endpoint that controls network traffic using numbered channels (0-65535).
TCP provides reliable connections; UDP offers faster
Standardized ports 0-1023 for common services like HTTP (80) and HTTPS (443).
To prevent unauthorized access
Creating firewall rules to allow traffic through a specific port number.
Well-known (0-1023)
Redirecting external traffic from one port to internal devices or services.
Temporary high-numbered ports automatically assigned for outbound client connections.
Port 80 for HTTP web traffic
SSH (Secure Shell) for encrypted remote access and file transfers.
SMTP (25/587)
Port 21 for FTP control
DNS services that translate domain names to IP addresses.
Remote Desktop Protocol (RDP) for Windows remote desktop connections.
Inbound controls incoming traffic; outbound controls traffic leaving your network.
Blocking all traffic except specifically allowed connections for maximum security.
They track connections and automatically allow return traffic for established sessions.
Security technique requiring specific port sequence before opening protected services.
Reduces attack surface
SSH (22)
Use intrusion detection systems
Telnet sends data unencrypted; use SSH port 22 instead.
Running outdated services
Network Address Translation using port numbers to share public IPs.
Applications automatically request available ports for temporary connections as needed.
Copying network traffic to monitoring ports for security analysis purposes.
Create rules specifying start and end port numbers for multiple services.
Isolated network zone with specific ports open for public-facing services.
Typically use UDP 1194 (OpenVPN) or UDP 500/4500 (IPSec) protocols.
Verify every connection regardless of location
Remember: Use all available resources to study. Flearn alone cannot guarantee success in any exams—make sure to supplement your learning!