Guidelines for securing DNS being updated

Draft of recommendations released for first of two rounds of public comment

The National Institute of Standards and Technology is updating its recommendations for meeting the unusual security challenges presented by the Domain Name System (DNS), which underpins much of the Internet by mapping user-friendly domain names to numerical IP addresses.

"The domain name data provided by DNS is intended to be publicly available to any computer located anywhere in the Internet,” NIST states in Special Publication 800-81, "Secure Domain Name System Deployment Guide." “Because DNS data is meant to be public, preserving the confidentiality of DNS data pertaining to publicly accessible IT resources is not a concern. The primary security goals for DNS are data integrity and source authentication, which are needed to ensure the authenticity of domain name information and maintain the integrity of domain name information in transit.”

Achieving those goals requires good network security practices that encompass up-to-date software patches, process isolation and fault tolerance, and the use of the more specific DNS Security Extensions (DNSSEC) to digitally sign and authenticate DNS query and response transactions. Agencies were required to implement DNSSEC in the .gov top-level domain this year. However, the deadline has slipped because the government has been waiting for improvement to the software being used. Second-level domains, such as nist.gov, are to be signed by the end of the year.

NIST outlined the following basic steps for deploying DNSSEC for zone information:
  • Install a DNSSEC-capable name server.
  • Check zone file(s) for possible integrity errors.
  • Generate asymmetric key pairs for each zone and include them in the zone file.
  • Sign the zone.
  •  Load the signed zone onto the server.
  • Configure the name server to turn on DNSSEC processing.
  • Send a copy of the public key to the parent for secure delegation (optional).
In addition to minor textual corrections, the guidance includes the following revisions:
  • Updated recommendations for cryptographic parameters based on NIST Special Publication 800-57.
  • A discussion of NSEC3 Resource Record in DNSSEC.
  • A discussion of DNSSEC in split-view deployments.
  • Minor fixes of examples and text.
  • Examples based on the name server daemon and Berkeley Internet Name Domain software.
NIST will hold two public commenting periods. The first one ends March 31; send your comments on the updated guidelines to secureDNS@nist.gov.

In addition to integrity and authentication, ensuring the availability of DNS services and data is also important. DNS components are subject to denial-of-service attacks that seek to block access to the domain names. The NIST document provides guidelines for configuring deployments to prevent many of the denial-of-service attacks targeted at DNS.

About the Author

William Jackson is a Maryland-based freelance writer.

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