Port Scanning

Simple Definition for Beginners:

Port scanning is a technique used to find open ports on a computer or network to identify potential vulnerabilities.

Common Use Example:

When a cybersecurity expert checks a network for open ports that hackers could exploit, they are performing port scanning.

Technical Definition for Professionals:

Port scanning involves systematically probing a server or network device to identify open ports and services, assess security vulnerabilities, and understand the communication protocols in use. Key aspects include:

• Types of Port Scans:

o TCP Connect Scan: Establishes a full TCP connection to the target port, identifying if the port is open.

o SYN Scan (Half-Open Scan): Sends a SYN packet to the target port and waits for a SYN-ACK response, without completing the TCP handshake. This is stealthier than a full TCP connect scan.

o UDP Scan: Sends UDP packets to target ports and waits for a response to determine if the port is open or closed. It is slower and less reliable due to the stateless nature of UDP.

o ACK Scan: Determines the firewall rules and whether the ports are filtered by sending ACK packets.

o FIN Scan: Sends a FIN packet to the target port. An open port typically ignores it, while a closed port responds with an RST packet.

• Purpose of Port Scanning:

o Security Assessment: Identify open ports and services to find potential entry points for attacks.

o Network Inventory: Map the network by identifying active devices and running services.

o Vulnerability Detection: Determine outdated software and unpatched vulnerabilities on open ports.

o Compliance Checks: Ensure that the network adheres to security policies by identifying unauthorized services.

• Common Tools for Port Scanning:

o Nmap: A popular open-source tool for network discovery and security auditing.

o Zenmap: The graphical user interface for Nmap.

o Masscan: Known for its ability to scan the entire Internet quickly.

o Netcat: A versatile networking tool used for port scanning and other network-related tasks.