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Nmap Network Scanning

The Official Nmap Project Guide to Network Discovery and Security Scanning

Gordon “Fyodor” Lyon

Book URL: https://nmap.org/book/
ISBN: 978-0-9799587-1-7
ISBN-10: 0-9799587-1-7

Nmap Network Scanning is the official guide to the Nmap Security Scanner, a free and open source utility used by millions of people for network discovery, administration, and security auditing. From explaining port scanning basics for novices to detailing low-level packet crafting methods used by advanced hackers, this book by Nmap's original author suits all levels of security and networking professionals. The reference guide documents every Nmap feature and option, while the remainder demonstrates how to apply them to quickly solve real-world tasks. Examples and diagrams show actual communication on the wire. Topics include subverting firewalls and intrusion detection systems, optimizing Nmap performance, and automating common networking tasks with the Nmap Scripting Engine.

Table of Contents

List of Figures

1. IPv4 header
2. TCP header
3. UDP header
4. ICMP header
1.1. Trinity begins her assault
1.2. Trinity scans the Matrix
1.3. Strong opinions on port scanning legality and morality
2.1. Executing Nmap from a Windows command shell
2.2. Apple Gatekeeper block screen
2.3. Apple Gatekeeper Open menu
2.4. Apple Gatekeeper Open screen
3.1. A business card explains everything
3.2. Netcraft finds 36 Target web servers
5.1. ICMPv4 destination unreachable header layout
5.2. SYN scan of open port 22
5.3. SYN scan of closed port 113
5.4. SYN scan of filtered port 139
5.5. Connect scan of open port 22
5.6. Idle scan of an open port
5.7. Idle scan of a closed port
5.8. Idle scan of a filtered port
5.9. Congestion window and threshold
5.10. Scan rate as affected by scan delay
8.1. ICMP echo request or reply header layout
8.2. ICMP destination unreachable header layout
10.1. BlackICE discovers an unusual intruder
10.2. An attacker masked by dozens of decoys
12.1. Typical Zenmap screen shot
12.2. Zenmap's main window
12.3. Target and profile selection
12.4. Host selection
12.5. OS icons
12.6. Service selection
12.7. Grouping a host's children
12.8. Highlighting regions of the topology
12.9. Choosing a profile
12.10. The profile editor
12.11. The “Scripting” profile editor tab
12.12. Host filter
12.13. The search dialog
12.14. Keyword search
12.15. Expressions search
12.16. Comparison tool
12.17. Comparison output
12.18. Zenmap in German
12.19. Setting the LANG environment variable on Windows XP
12.20. Setting the LANG environment variable on Mac OS X
13.1. HTML from XML output in a web browser

List of Tables

List of Examples

1. A typical Nmap scan
1.1. Nmap list scan against Avatar Online IP addresses
1.2. Nmap results against an AO firewall
1.3. Another interesting AO machine
1.4. nmap-diff typical output
1.5. nmap-report execution
2.1. Checking for Nmap and determining its version number
2.2. Verifying the Nmap and Fyodor PGP Key Fingerprints
2.3. Verifying PGP key fingerprints (Successful)
2.4. Detecting a bogus file
2.5. A typical Nmap release digest file
2.6. Verifying Nmap hashes
2.7. Successful configuration screen
2.8. Installing Nmap from binary RPMs
2.9. Building and installing Nmap from source RPMs
2.10. Installing Nmap from a system Yum repository
3.1. Using the host command to query common DNS record types
3.2. Zone transfer failure and success
3.3. Nmap reverse-DNS and traceroute scan against www.target.com
3.4. Using whois to find owner of www.target.com IP address
3.5. Using whois to find netblock containing 161.225.130.163
3.6. Enumerating hosts surrounding www.stanford.edu with list scan
3.7. Discovering hosts surrounding www.lwn.net with a ping scan
3.8. Attempts to ping popular Internet hosts
3.9. Retry host discovery using port 80 SYN probes
3.10. Attempted ACK ping against Microsoft
3.11. Raw IP ping scan of an offline target
3.12. ARP ping scan of an offline target
3.13. Generating 50,000 IP addresses, then ping scanning with default options
3.14. Repeating ping scan with extra probes
4.1. Viewing and increasing the ephemeral port range on Linux
4.2. Simple scan: nmap scanme.nmap.org
4.3. More complex: nmap -p0- -v -A -T4 scanme.nmap.org
4.4. A simple IPv6 scan
4.5. Discovering Playboy's IP space
4.6. Pinging Playboy's web server for a latency estimate
4.7. Digging through Playboy's DNS records
4.8. Pinging the MX servers
4.9. TCP pinging the MX servers
4.10. Launching the scan
4.11. Egrep for open ports
5.1. A SYN scan showing three port states
5.2. Using --packet-trace to understand a SYN scan
5.3. Connect scan example
5.4. UDP scan example
5.5. UDP scan example
5.6. Improving Felix's UDP scan results with version detection
5.7. Improving Scanme's UDP scan results with version detection
5.8. Attempting to disambiguate UDP ports with TTL discrepancies
5.9. Optimizing UDP Scan Time
5.10. Example FIN and Xmas scans
5.11. SYN scan of Docsrv
5.12. FIN scan of Docsrv
5.13. A SYN/FIN scan of Google
5.14. A custom PSH scan
5.15. A typical ACK Scan
5.16. An ACK scan of Docsrv
5.17. Window scan of docsrv.caldera.com
5.18. A failed Maimon scan
5.19. An idle scan against the RIAA
5.20. IP protocol scan of a router and a typical Linux 2.4 box
5.21. Attempting an FTP bounce scan
5.22. Successful FTP bounce scan
6.1. Bandwidth usage over local 100 Mbps ethernet network
6.2. Estimating scan time
7.1. Simple usage of version detection
7.2. Version detection against www.microsoft.com
7.3. Complex version detection
7.4. NULL probe cheat example output
7.5. Enumerating RPC services with rpcinfo
7.6. Nmap direct RPC scan
7.7. Version scanning through SSL
8.1. OS detection with verbosity (-O -v)
8.2. Using version scan to detect the OS
8.3. A typical subject fingerprint
8.4. A cleaned-up subject fingerprint
8.5. A typical reference fingerprint
8.6. Some typical fingerprint descriptions and corresponding classifications
8.7. Typical CPE classifications
8.8. An IPv6 fingerprint
8.9. A cleaned-up IPv6 fingerprint
8.10. The MatchPoints structure
8.11. Scan results against a consumer WAP
9.1. Typical NSE output
9.2. Script help
9.3. Connect-style I/O
9.4. Automatic formatting of NSE structured output
9.5. NSE structured output in XML
9.6. Exception handling example
9.7. An NSEDoc comment for a function
9.8. An NSEDoc comment for a module
9.9. An NSEDoc comment for a script
9.10. Worker threads
9.11. Mutex manipulation
9.12. Basic Coroutine Use
9.13. Link Generator
9.14. A typical version detection script (Skype version 2 detection)
10.1. Detection of closed and filtered TCP ports
10.2. ACK scan against Scanme
10.3. Contrasting SYN and ACK scans against Para
10.4. UDP scan against firewalled host
10.5. UDP version scan against firewalled host
10.6. FIN scan against stateless firewall
10.7. Bypassing Windows IPsec filter using source port 88
10.8. Comparing IPv4 and IPv6 scans
10.9. Exploiting a printer with the FTP bounce scan
10.10. Some interesting hosts and networks at Megacorp
10.11. Ping scan against the target network
10.12. Packet trace against a single IP
10.13. Testing an idle scan
10.14. Testing source routing
10.15. Success at last
10.16. Host names can be deceiving
10.17. Noting TTL gaps with traceroute
10.18. Using the IP record route option
10.19. Slow scan to bypass the default Snort 2.2.0 Flow-portscan fixed time scan detection method
10.20. Default Snort rules referencing Nmap
10.21. Using DNS Proxies (Recursive DNS) for a Stealth List Scan of SecurityFocus
10.22. Detection of closed and filtered TCP ports
10.23. Testing IP ID sequence number consistency
10.24. Finding a firewall with bad TCP checksums
11.1. An all-TCP-port version scan
11.2. Deceiving Nmap with IP Personality
13.1. Scanrand output against a local network
13.2. Grepping for verbosity conditionals
13.3. Interactive output without verbosity enabled
13.4. Interactive output with verbosity enabled
13.5. Some representative debugging lines
13.6. Using --packet-trace to detail a ping scan of Scanme
13.7. A typical example of normal output
13.8. A typical example of $crIpt KiDDi3 0utPut
13.9. An example of Nmap XML output
13.10. Nmap XML port elements
13.11. Nmap::Parser sample code
13.12. Nmap::Scanner sample code
13.13. Normal output with CPE highlighted
13.14. A typical example of grepable output
13.15. Ping scan grepable output
13.16. List scan grepable output
13.17. Grepable output for IP protocol scan
13.18. Parsing grepable output on the command line
14.1. Excerpt from nmap-services
14.2. Excerpt from nmap-service-probes
14.3. Excerpt from nmap-rpc
14.4. Excerpt from nmap-os-db
14.5. Excerpt from nmap-mac-prefixes
14.6. Excerpt from nmap-protocols
15.1. A representative Nmap scan
16.1. Ndiff text output
16.2. Ndiff XML output
16.3. Scanning a network periodically with Ndiff and cron
18.1. A representative Nping execution
18.2. Discovering NAT devices
18.3. Discovering a transparent proxy