Turn off your SMTP, Telnet and HTTP banners

When you Telnet to your mail server (port 25) from a command line, (c:telnet 25), it displays what SMTP server you are running. The same goes for Telnet(23) and HTTP(80) ports. This leads to an "OS Fingerprint" so hackers can decide on what vulnerabilities you have to attack. What can you do to block this in Windows 2000? Use the Meta Editor provided free of charge from Microsoft. For more information see http://www.iisfaq.com/?View=A385&P=109 and download the editor at http://support.microsoft.com/support/kb/articles/Q232/0/68.ASP.

This editor works for the SMTP service bundled with Windows 2000 server and for Exchange. For Windows 2003 people, change the default connection response that you receive after you connect to the SMTP port in Exchange 2003. For more information see: http://support.microsoft.com/?id=836564.

For Telnet banners: Change the Telnet Server Banner and Run Programs for All Users. See Microsoft Knowledge Base Article 245095 for more information.

For HTTP banners -- sorry I couldn't find a free way to do this – try http://www.port80software.com/products/servermask/.

This way you won't be telling the hackers what type of Microsoft OS/application your running. If you've never heard about OS fingerprinting and what can become of it, read this abstract at: http://www.insecure.org/nmap/nmap-fingerprinting-article.html.

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