From FedoraProject

< Features
Revision as of 22:22, 11 March 2009 by Pwouters (Talk | contribs)

Jump to: navigation, search


Feature Name

DNSSEC - Enable DNSSEC and DLV security extensions for DNS and prime validating resolvers with DNSSEC keys.


DNSSEC (DNS SECurity) is mechanism which provides integrity and authenticity of DNS data. It became more important after new Kaminsky DNS poisoning attacks were found in early 2008. The most widely used recursing nameservers support DNSSEC. We currently support it for bind and unbound.


Current status

  • Targeted release: Fedora 21
  • Last updated: 2009-03-03
  • Percentage of completion: 99% (commandline tool dnssec-conf and bind/unbound integration finished 100%, GUI system-config-dnssec finished 70%)

Detailed Description

Important servers already support DNSSEC. Main problem is key distribution. A full validation path would start at the root (".") but it is not likely that the root will be signed very soon. There are two methods for working around not having a signed root:

  • Using Trust Anchor Repositories (TAR's or "batched TAR") for TLD keys
  • Using DNSSEC Lookaside Verification (DLV or "live TAR") for enduser domains within an unsigned TLD.

This feature adds support for both TAR and DLV support, using the following approach:

  • supply initial set of DNSSEC keys for TLD's (and perhaps some "very important domains") as long as the root is not signed. This is done via dnssec-conf)
  • allow easy way to enable/disable DNSSEC via commandline tool dnssec-configure from the dnssec-conf package (completed)
  • allow easy way to enable/disable DNSSEC via GUI tool system-config-dnssec tool (70% completed)
  • allow configuration of any DLV Registry, with the default set to ISC, using the above two mentioned tools (completed)
  • support for automated Trust Anchor Rollovers from DNS information via the autotrust package using secure RFC5011 update mechanism. This is in addition to updates supplied via the dnssec-conf package. (completed)

Benefit to Fedora

Our servers (and clients) will be able to use DNSSEC, and be safer against cache poisoning, Kaminsky attacks, spoofing and other known DNS attacks. Fedora machines will also be able to use signed TLD's and individually signed domains in DLV without any additional administration. For example, right now that already gives you DNSSEC for the entire .gov domain, plus a handful of TLD's and a few dozen in-arpa domains including the ENUM zone.


  • create and add a package dnssec-conf which will supply initial set of DNSSEC keys to machines. (completed)
  • Do not yet enable DNSSEC in default bind and unbound configurations. But make it trivially easy to enable DNSSEC via dnssec-conf. (completed)
  • create commandline tool (dnssec-configure from the dnssec-conf package) that will easily enable/disable DNSSEC and which allows to switch between DLV Registries and supplied DNSSEC keys (completed)
  • add the "autotrust" package which implements RFC 5011 - "Automated Updates of DNS Security (DNSSEC) Trust Anchors". This package includes a daily cronjob that will try to update any configured DNSSEC trust anchors from the dnssec-conf package, and any manually installed trust anchors by the administrator. (completed)
  • create system-config-dnssec GUI tool to enable / disable the most important features (70% done)
  • Update the Bind and Unbound packages so the default configurations enable DNSSEC for Fedora-11

How To Install

 yum install bind-utils
 yum install bind (or unbound or both)

This should bring in dnssec-conf. You can verify the installation using:

 dnssec-configure -s

DNSSEC is enabled per default, DLV is not. If you want to enable DLV too, run:

 dnssec-configure --dnssec=on --dlv=on
 service named restart (or service unbound restart)

For the GUI, use

 yum install system-config-dnssec

Navigate to System->Administration->DNSSEC

(system-config-dnssec is not yet finished)

How to Test

 dig +dnssec +multiline -t ns gov. @localhost

You should see the AD bit in the reply, as well as the RRSIG signature record:

$ dig +dnssec +multiline -t ns gov. @
; <<>> DiG 9.5.1b3-RedHat-9.5.1-0.9.b3.fc10 <<>> +dnssec +multiline -t ns gov. @localhost
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14948
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: version: 0, flags: do; udp: 4096
;gov.			IN NS

gov.			259188 IN NS G.GOV.ZONEEDIT.COM.
gov.			259188 IN NS A.GOV.ZONEEDIT.COM.
gov.			259188 IN NS C.GOV.ZONEEDIT.COM.
gov.			259188 IN NS E.GOV.ZONEEDIT.COM.
gov.			259188 IN NS D.GOV.ZONEEDIT.COM.
gov.			259188 IN NS F.GOV.ZONEEDIT.COM.
gov.			259188 IN NS B.GOV.ZONEEDIT.COM.
gov.			259188 IN RRSIG	NS 7 1 259200 20090309210102 (
				20090304210102 31802 gov.
				vVPg33HHycdslVP2s+mtthkW9wcAC9+IMA== )

;; Query time: 122 msec
;; WHEN: Wed Mar  4 18:07:11 2009
;; MSG SIZE  rcvd: 451

If you want to see more DNSSEC related records run:

 dig +multiline +dnssec -t any gov. @localhost

To verify that forged/broken data is properly refused, you can test against some test zones:

 dig +multiline +dnssec forged.test.xelerance.com @localhost

This should produce a ServFail answer. To force getting the known bad answer, run:

 dig +multiline +dnssec +cd forged.test.xelerance.com @localhost

This should produce the forged/broken answer despite its known forgery.

User Experience

Easy configuration and priming of DNSSEC aware resolvers.

Related Packages



Contingency Plan

Disable DNSSEC by default in /usr/sysconfig/dnssec and release a software update of dnssec-conf



Release Notes

Bind and unbound (recursive DNS servers) now enable DNSSEC validation in their default configuration. DNSSEC Lookaside Verification (DLV) is not yet enabled. This behaviour can be modified in /etc/sysconfig/dnssec by changing the DNSSEC and DLV settings.

With DNSSEC enabled, when a domain supplies DNSSEC data (such as .gov, .se, the ENUM zone and other TLD's) then that data will be cryptographically validated on the recursive DNS server. If validation fails, due to attempts at cache poisoning (eg via a Kaminsky Attack) then the enduser will not be given this forged/spoofed data. DNSSEC deployment is gaining speed rapidly, and is a crucial part and the next logical step to make the internet more secure for end users.

Comments and Discussion