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EC-Council

312-50V9 · Question #471

How can telnet be used to fingerprint a web server?

The correct answer is A. telnet webserverAddress 80. Connecting to a web server on port 80 via Telnet and sending a HEAD or GET request reveals the server's HTTP response headers, which often include the server software and version.

Hacking Web Servers

Question

How can telnet be used to fingerprint a web server?

Options

  • Atelnet webserverAddress 80
  • Btelnet webserverAddress 80
  • Ctelnet webserverAddress 80
  • Dtelnet webserverAddress 80

How the community answered

(41 responses)
  • A
    88% (36)
  • B
    7% (3)
  • C
    2% (1)
  • D
    2% (1)

Why each option

Connecting to a web server on port 80 via Telnet and sending a HEAD or GET request reveals the server's HTTP response headers, which often include the server software and version.

Atelnet webserverAddress 80Correct

By running 'telnet webserverAddress 80' and then manually typing an HTTP request such as 'HEAD / HTTP/1.0', the response includes the 'Server:' header field that discloses the web server software, version number, and sometimes the OS. This banner-grabbing technique works because HTTP is a plaintext protocol and Telnet provides raw TCP access to any port. It is a foundational reconnaissance step in penetration testing and security assessments.

Btelnet webserverAddress 80

This choice is identical to A and does not represent a distinct technique.

Ctelnet webserverAddress 80

This choice is identical to A and does not represent a distinct technique.

Dtelnet webserverAddress 80

This choice is identical to A and does not represent a distinct technique.

Concept tested: Banner grabbing via Telnet on HTTP port 80

Source: https://owasp.org/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/01-Information_Gathering/02-Fingerprint_Web_Server

Topics

#telnet#web server fingerprinting#banner grabbing#HTTP

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