Nmap clock-skew NSE Script

Script Overview

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Script source code: https://github.com/nmap/nmap/tree/master/scripts/clock-skew.nse
Script categories: default, safe
Target service / protocol: -
Target network port(s): various
List of CVEs: -

Script Description

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The clock-skew.nse script analyzes the clock skew between the scanner and various services that report timestamps.

At the end of the scan, it will show groups of systems that have similar median clock skew among their services. This can be used to identify targets with similar configurations, such as those that share a common time server.

You must run at least 1 of the following scripts to collect clock data:

• bitcoin-info
• http-date
• http-ntlm-info
• imap-ntlm-info
• memcached-info
• ms-sql-ntlm-info
• nntp-ntlm-info
• ntp-info
• openwebnet-discovery
• pop3-ntlm-info
• rfc868-time
• smb-os-discovery
• smb-security-mode
• smb2-time
• smb2-vuln-uptime
• smtp-ntlm-info
• ssl-date
• telnet-ntlm-info

Clock-skew NSE Script Arguments

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The clock-skew.nse script does not have any arguments.

Clock-skew NSE Script Example Usage

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Here's an example of how to use the clock-skew.nse script:

nmap --script=clock-skew <target>

Clock-skew NSE Script Example Output

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Here's a sample output from the clock-skew.nse script:

Host script results:
|_clock-skew: mean: -13s, deviation: 12s, median: -6s

Post-scan script results:
| clock-skew:
|  -6s: Majority of systems scanned
|  3s:
|    192.0.2.5
|_   192.0.2.7 (example.com)

Clock-skew NSE Script Example XML Output

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Here's a sample XML output from the clock-skew.nse script produced by providing the -oX <file> Nmap option:

 <elem key="stddev">12.124355652982</elem>
 <elem key="mean">-13.0204495</elem>
 <elem key="median">-6.0204495</elem>

Author

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• Daniel Miller

References

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• https://nmap.org/nsedoc/scripts/clock-skew.html
• https://github.com/nmap/nmap/tree/master/scripts/clock-skew.nse

See Also

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Visit Nmap NSE Library for more scripts.