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Questions and Answers
What is the primary reason why inexperienced users rely on the default SYN scan?
What is the primary function of Nmap in port scanning?
What is the status of an open port?
What is the primary characteristic of a filtered port?
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What is the purpose of using various application for ping sweep discovery?
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What is the primary difference between an open port and a closed port?
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What is the benefit of using Nmap to perform port scanning?
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What is the primary difference between a SYN scan and other scanning techniques?
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What is the primary goal of port scanning?
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What is the primary advantage of using Nmap for port scanning?
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Study Notes
Network Hacking (Scanning Networks)
- Scanning networks is Phase 2 of the 5 phases of Ethical Hacking, where we interact with target systems from information gathered in reconnaissance and footprinting phase.
Ping Sweeps
- Ping sweeps are used to identify active and responding systems within an IP address space.
- It helps to avoid wasting time and resources on scanning non-existent systems.
- Many tools are available for ping sweeps, including fping, masscan, Nmap, and netdiscover.
- Fping is a tool that sends ICMP echo requests to multiple systems, showing hosts that are active, elapsed time, and generating a list of targets from an address block.
- Fping requires being mindful of host-based firewalls, as systems may not respond to ICMP.
- Examples of ping sweep commands include
fping -qag 192.168.17.0/24andsudo netdiscover -r 192.168.17.0/24.
Port Scanning
- TCP/IP port numbers exist at the transport layer of the OSI reference model.
- TCP and UDP ports range from 0-65535 and can be open or closed, bounded to applications or services.
- Port scanning serves to identify software and versions used by the target to provide services.
- Nmap is a popular tool for port scanning, capable of scanning both TCP and UDP ports.
- Nmap supports detection of operating system types, applications, and application versions.
- Nmap scripts can be used for extended functions, categorized into types like auth, broadcast, default, discovery, dos, exploit, external, fuzzer, intrusive, malware, safe, version, and vuln.
Types of Port Scans
- SYN Scan (or half-open scan) requires root privilege to modify raw packets and uses the
nmap -sSoption. - SYN Scan does not complete the TCP 3-way handshake, instead, sending a TCP RST (Reset) packet.
- TCP Scan (or full connect scan) completes the TCP 3-way handshake using the
nmap -sToption. - Nmap can output port status, which can be open, closed, or filtered.
Nmap Port Status
- Open port: active and responding.
- Closed port: not active and not responding.
- Filtered port: possible firewall, filter, or other network obstacle is blocking the port, so Nmap cannot tell whether it is open or closed.
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Description
This quiz covers the basics of ping sweeps, including how to use fping to scan a subnet. Learn about the importance of ping sweeps in network hacking.
