software package is a simple and security-aware DNS
implementation created by Daniel J. Bernstein
due to his frustrations with repeated BIND security holes
. There is an as-yet-unclaimed $1000 prize for the first person to find a privilege escalation security hole
As of 2004, it was the second most popular DNS server.
djbdns has never been vulnerable to the cache-poisoning vulnerability reported in July 2008.
The components of djbdns
- dnscache -- the dns resolver and cache.
- tinydns -- a database-driven dns server.
- walldns -- a "reverse DNS wall", providing IP 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 requester's location. (This feature is now a standard part of tinydns.)
- axfrdns -- a zone-transfer server.
- 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.
...and several associated configuration tools.
In djbdns, different features and services, such as AXFR zone transfers, are split off into separate programs. Zone file parsing, DNS caching, and recursive resolving are also implemented as separate programs. The result of these design decisions is a dramatic reduction in code size and complexity of the daemon program that answers lookup requests. Daniel J. Bernstein (and many others) feel that this is true to the spirit of the Unix operating system, and makes security verification much simpler.
On December 28
, Bernstein released djbdns into the public domain
. Formerly, the package was distributed as license-free software
, which created challenges for inclusion in some Linux