May 2017
Intermediate to advanced
416 pages
21h 33m
English
Content preview from Nmap: Network Exploration and Security Auditing Cookbook - Second Edition
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How it works...
The smtp-open-relay script was submitted by Arturo Buanzo Busleiman, and it attempts 16 different tests to determine if an SMTP server allows open relaying. If verbose mode is on, it also returns the commands that successfully relayed the e-mails.
The command combination is hardcoded in the script, and the tests consist of different string formats for the destination and source address:
MAIL FROM:<user@domain.com> 250 Address Ok. RCPTTO:<user@adomain.com> 250 user@adomain.com OK
If a 503 response is received, the script exits because this means that this server is protected by authentication and is not an open relay.
The smtp-open-relay script executes if ports 25, 465, and 587 are open, or if the services smtp, smtps, or ...
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