The djbdns software package is a DNS implementation. It was created by Daniel J. Bernstein in response to his frustrations with repeated security holes in the widely used

BIND BIND () is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named (pronounced ''name-dee'': , short for ''name daemon''), performs both of the main DNS server roles, acting as an authoritative ...

DNS software. As a challenge, Bernstein offered a $1000 prize for the first person to find a security hole in djbdns, which was awarded in March 2009 to Matthew Dempsky. , djbdns's tinydns component was the second most popular DNS server in terms of the number of domains for which it was the authoritative server, and third most popular in terms of the number of DNS hosts running it. djbdns has never been vulnerable to the widespread cache poisoning vulnerability reported in July 2008, but it has been discovered that it is vulnerable to a related attack. The

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the w ...

has not been centrally managed since its release in 2001, and was released into the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

in 2007. As of March 2009, there are a number of forks, one of which is dbndns (part of the

Debian Project Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of Deb ...

), and more than a dozen patches to modify the released version. While djbdns does not directly support

DNSSEC The Domain Name System Security Extensions (DNSSEC) are a suite of extension specifications by the Internet Engineering Task Force (IETF) for securing data exchanged in the Domain Name System (DNS) in Internet Protocol (IP) networks. The protoc ...

, there are third party patches to add DNSSEC support to djbdns' authoritative-only tinydns component.

Components

The djbdns software consists of servers, clients, and miscellaneous configuration tools.

Servers

* dnscache — the DNS resolver and cache. * tinydns — a database-driven DNS server. * walldns — a "reverse DNS wall", providing IP address-to-domain name lookup only. * rbldns — a server designed for DNS blacklisting service. * pickdns — a database-driven server that chooses from matching records depending on the requestor's location. (This feature is now a standard part of tinydns.) * axfrdns — a zone transfer server.

Client tools

* axfr-get — a zone-transfer client. * dnsip — simple address from name lookup. * dnsipq — address from name lookup with rewriting rules. * dnsname — simple name from address lookup. * dnstxt — simple text record from name lookup. * dnsmx — mail exchanger lookup. * dnsfilter — looks up names for addresses read from stdin, in parallel. * dnsqr — recursive general record lookup. * dnsq — non-recursive general record lookup, useful for debugging. * dnstrace (and dnstracesort) — comprehensive testing of the chains of authority over DNS servers and their names.

Design

In djbdns, different features and services are split off into separate programs. For example, zone transfers, zone file parsing, caching, and

recursive Recursion (adjective: ''recursive'') occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in mathematics ...

resolving are implemented as separate programs. The result of these design decisions is a reduction in code size and complexity of the

daemon Daimon or Daemon (Ancient Greek: , "god", "godlike", "power", "fate") originally referred to a lesser deity or guiding spirit such as the daimons of ancient Greek religion and Greek mythology, mythology and of later Hellenistic religion and Hell ...

program that provides the core function of answering lookup requests. Bernstein asserts that this is true to the spirit of the

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...

operating system, and makes security verification much simpler.

Copyright status

On December 28, 2007, Bernstein released djbdns into the

. Previously the package was distributed free of charge as license-free software. However this did not permit the distribution of modified versions of djbdns, which was one of the core principles of

open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Op ...

. Consequently, it was not included in those Linux distributions which required all components to be open-source.

References

External links

djbdns official homepageN-DJBDNSA guide to djbdnsThe djbdns section of FAQTSA djbdns guide and tutorial with addon
* — Jonathan de Boyne Pollard's debunking of several myths relating to djbdns *{{cite web, url=http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/djbdns-problems.html, title=The known problems with Dan Bernstein's djbdns, author=Jonathan de Boyne Pollard, work=Frequently Given Answers, access-date=2009-09-20, archive-url=https://web.archive.org/web/20100425055845/http://homepage.ntlworld.com/jonathan.deboynepollard/FGA/djbdns-problems.html, archive-date=2010-04-25, url-status=dead — Jonathan de Boyne Pollard's list of the several known problems in djbdns
Supporting newer record formats through generic records.LWN (Linux weekly news) looks at djbdns
DNS software Public-domain software with source code DNS server software for Linux