Active reconnaissance is a crucial phase in penetration testing where the tester interacts directly with the target system to gather information. Unlike passive reconnaissance, which involves collecting data without direct interaction, active reconnaissance involves probing the target to uncover details that are not publicly available. This phase can reveal open ports, services, and potential vulnerabilities that can be exploited in later stages.

1. Direct Interaction: Engaging with the target system through various techniques and tools to gather information.
2. Network Mapping: Identifying the structure and devices within a network.
3. Service Detection: Determining which services are running on open ports.
4. Vulnerability Scanning: Identifying potential security weaknesses in the target system.

Ping sweeps involve sending ICMP echo requests to multiple IP addresses to determine which hosts are active. This helps in identifying live systems within a network.

Example:

Explanation: The fping command sends ICMP echo requests to the entire subnet 192.168.1.0/24 and lists the active hosts.

Port scanning is used to identify open ports on a target system. This helps in understanding which services are accessible and potentially exploitable.

Example:

Explanation: The nmap -sS command performs a TCP SYN scan on the target IP 192.168.1.10, identifying open ports.

Service enumeration involves probing open ports to determine the services running on them and their versions. This information is crucial for identifying vulnerabilities.

Example:

Explanation: The nmap -sV command performs version detection on the target IP 192.168.1.10, identifying the services and their versions running on open ports.

Banner grabbing involves connecting to a service and reading the welcome message or banner, which often contains information about the service and its version.

Example:

Explanation: The nc (Netcat) command connects to the target IP 192.168.1.10 on port 80 (HTTP) and displays the banner information.

Vulnerability scanning tools are used to identify known vulnerabilities in the target system based on the services and versions detected.

Example:

Explanation: The openvas-start command initializes the OpenVAS vulnerability scanner, which can then be used to scan the target system for known vulnerabilities.

Objective: Perform a port scan on a target IP to identify open ports.

Steps:

1. Open a terminal.
2. Use Nmap to scan the target IP 192.168.1.10 for open ports.

   nmap -sS 192.168.1.10
   

3. Analyze the output to identify open ports.

Solution: The output should list the open ports on the target IP, such as:

Objective: Enumerate services running on the open ports identified in Exercise 1.

Steps:

1. Open a terminal.
2. Use Nmap to perform service enumeration on the target IP 192.168.1.10.

   nmap -sV 192.168.1.10
   

3. Analyze the output to identify the services and their versions.

Solution: The output should provide details about the services and their versions, such as:

• Mistake: Overlooking firewall and IDS/IPS alerts. Tip: Be aware that active reconnaissance can trigger security alerts. Use stealth techniques and understand the target's security posture.

• Mistake: Misinterpreting scan results. Tip: Verify findings with multiple tools and cross-reference results to ensure accuracy.

• Mistake: Ignoring service versions. Tip: Service versions are crucial for identifying vulnerabilities. Always perform service enumeration after port scanning.

Active reconnaissance is a vital step in penetration testing that involves direct interaction with the target system to gather detailed information. By using techniques such as ping sweeps, port scanning, service enumeration, banner grabbing, and vulnerability scanning, testers can uncover valuable insights into the target's security posture. Understanding and practicing these techniques will prepare you for the subsequent phases of exploitation and post-exploitation in penetration testing.