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How do I restrict people from looking up the server version?
Author: ISC Support Reference Number: AA-00307 Views: 1896 Created: 2011-05-16 14:20 Last Updated: 2017-01-25 01:18 0 Rating/ Voters

By default, BIND servers will answer a query in the chaos domain for a text record named "version.bind" (for example: "dig @127.0.0.1 ch txt version.bind") with a string containing information about the server.

By default named will answer this query with the software version number of the server.  However, the answer is customizable by the operator -- if you wish to specify an answer that BIND will give instead, put a "version" option containing something other than the real version in the "options" section of named.conf, e.g. 'version "none of your business.";' or 'version none;' (where "none" is a special value which prevents the server from answering at all.

Note: many operators choose to do this, feeling that providing unnecessary information to attackers can only be harmful.  However, doing this will not prevent attacks and may impede people trying to diagnose problems with your server. Also, it is often possible to "fingerprint" nameservers to determine their version from the way they respond to specific queries, so suppressing the actual version string may not prevent an attacker from deducing your version from other clues..


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