Tag Archives: dnssec-keygen

"Chain" by Astro is licensed under CC BY 2.0

DNSSEC with NSEC3

By default DNSSEC uses the next secure (NSEC) resource record “to provide authenticated denial of existence for DNS data”, RFC 4034. This feature creates a complete chain of all resource records of a complete zone. While it has its usage to prove that no entry exists between two other entries, it can be used to “walk” through a complete zone, known as zone enumeration. That is: an attacker can easily gather all information about a complete zone by just using the designed features of DNSSEC.

For this reason NSEC3 was introduced: It constructs a chain of hashed and not of plain text resource records (RFC 5155). With NSEC3 enabled it is not feasible anymore to enumerate the zone. The standard uses a hash function and adds the NSEC3PARAM resource record to the zone which provides some details such as the salt.

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"Keys" by Rosa Say is licensed under CC BY-NC-ND 2.0

DNSSEC ZSK Key Rollover

One important maintenance requirement for DNSSEC is the key rollover of the zone signing key (ZSK). With this procedure a new public/private key pair is used for signing the resource records, of course without any problems for the end user, i.e., no falsified signatures, etc.

In fact it is really simply to rollover the ZSK with BIND. It is almost one single CLI command to generate a new key with certain time ranges. BIND will use the correct keys at the appropriate time automatically. Here we go:

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