ADC

Zone maintenance

September 14, 2021

Contributed by:

S S

From a DNSSEC perspective, zone maintenance involves rolling over Zone Signing Keys and Key Signing Keys when key expiry is imminent. These zone maintenance tasks must be performed manually. The zone is re-signed automatically and does not require any manual intervention.

Re-sign an updated zone

When a zone is updated (add a record or modify an existing record), the appliance automatically re-signs the new (or modified) record. If a zone contains multiple zone signing keys, the appliance re-signs the new (or modified) record with the key used to sign the zone.

Roll over DNSSEC keys

Note: Manually roll over the DNSSEC keys (KSK, ZSK) before they expire.

On the Citrix ADC, you can use the prepublish and double signature methods to perform a rollover of the Zone Signing Key and Key Signing Key. More information about these two rollover methods is available in RFC 4641, “DNSSEC Operational Practices.”

The following topics map commands on the ADC to the steps in the rollover procedures discussed in RFC 4641.

The key expiry notification is sent through an SNMP trap called dnskeyExpiry. Three MIB variables, dnskeyName, dnskeyTimeToExpire, and dnskeyUnitsOfExpiry are sent along with the dnskeyExpiry SNMP trap. For more information, see Citrix NetScaler SNMP OID Reference at NetScaler 12.0 SNMP OID Reference.

Prepublish key rollover

RFC 4641, “DNSSEC Operational Practices” defines four stages for the prepublish-key rollover method: initial, new DNSKEY, new RRSIGs, and DNSKEY removal. Each stage is associated with a set of tasks that you must perform on the ADC. Following are the descriptions of each stage and the tasks that you must perform. The rollover procedure described here can be used for both Key Signing Keys and Zone Signing Keys.

Stage 1: Initial. The zone contains only those key sets with which the zone has currently been signed. The state of the zone in the initial stage is the state of the zone just before you begin the key rollover process.

Example:

Consider the key, example.com.zsk1, with which the zone example.com is signed. The zone contains only those RRSIGs generated by the example.com.zsk1 key, which is due for expiry. The Key Signing Key is example.com.ksk1.
Stage 2: New DNSKEY. A new key is created and published in the zone. That is, the key is added to the ADC, but the zone is not signed with the new key until the pre-roll phase is complete. In this stage, the zone contains the old key, the new key, and the RRSIGs generated by the old key. Publishing the new key for the complete duration of the pre-roll phase gives the DNSKEY resource record corresponding to the new key time to propagate to the secondary name servers.

Example:

A new key example.com.zsk2 is added to the example.com zone. The zone is not signed with example.com.zsk2 until the pre-roll phase is complete. The example.com zone contains DNSKEY resource records for both example.com.zsk1 and example.com.zsk2.

Citrix ADC commands:

Perform the following tasks on the ADC:
- Create a DNS key by using the create dns key command.
  
  For more information about creating a DNS key, including an example, see Create DNS keys for a zone.
- Publish the new DNS key in the zone by using the add dns key command.
  
  For more information about publishing the key in the zone, including an example, see Publish a DNS key in a zone.
Stage 3: New RRSIGs. The zone is signed with the new DNS key and then unsigned with the old DNS key. The old DNS key is not removed from the zone and remains published until the RRSIGs generated by the old key expire.

Example:

The zone is signed with example.com.zsk2 and then unsigned with example.com.zsk1. The zone continues to publish example.com.zsk1 until the RRSIGs generated by example.com.zsk1 expire.

Citrix ADC commands:

Perform the following tasks on the ADC:
- Sign the zone with the new DNS key by using the sign dns zone command.
- Unsign the zone with the old DNS key by using the unsign dns zone command.
For more information about signing and unsigning a zone, including examples, see Sign and unsign a DNS zone.
Stage 4: DNSKEY Removal. When the RRSIGs generated by the old DNS key expire, the old DNS key is removed from the zone.

Example:

The old DNS key example.com.zsk1 is removed from the example.com zone.

Citrix ADC commands

On the ADC, you remove the old DNS key by using the rm dns key command. For more information about removing a key from a zone, including an example, see Remove a DNS key.

Double signature key rollover

RFC 4641, “DNSSEC Operational Practices” defines three stages for double signature key rollover: initial, new DNSKEY, and DNSKEY removal. Each stage is associated with a set of tasks that you must perform on the ADC. Following are the descriptions of each stage and the tasks that you must perform. The rollover procedure described here can be used for both Key Signing Keys and Zone Signing Keys.

Stage 1: Initial. The zone contains only those key sets with which the zone has currently been signed. The state of the zone in the initial stage is the state of the zone just before you begin the key rollover process.

Example:

Consider the key, example.com.zsk1, with which the zone example.com is signed. The zone contains only those RRSIGs generated by the example.com.zsk1 key, which is due for expiry. The Key Signing Key is example.com.ksk1.
Stage 2: New DNSKEY. The new key is published in the zone and the zone is signed with the new key. The zone contains the RRSIGs that are generated by the old and the new keys. The minimum duration for which the zone must contain both sets of RRSIGs is the time required for all the RRSIGs to expire.

Example:

A new key example.com.zsk2 is added to the example.com zone. The zone is signed with example.com.zsk2. The example.com zone now contains the RRSIGs generated from both keys.

Citrix ADC commands

Perform the following tasks on the ADC:
- Create a DNS key by using the create dns key command.
  
  For more information about creating a DNS key, including an example, see Create DNS keys for a zone.
- Publish the new key in the zone by using the add dns key command.
  
  For more information about publishing the key in the zone, including an example, see Publish a DNS key in a zone.
- Sign the zone with the new key by using the sign dns zone command.
  
  For more information about signing a zone, including examples, see Sign and unsign a DNS zone.
Stage 3: DNSKEY Removal. When the RRSIGs generated by the old DNS key expire, the old DNS key is removed from the zone.

Example:

The old DNS key example.com.zsk1 is removed from the example.com zone.

Citrix ADC commands:

On the ADC, you remove the old DNS key by using the rm dns key command.

For more information about removing a key from a zone, including an example, see Remove a DNS key.

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Zone maintenance

September 14, 2021

Contributed by:

S S

September 14, 2021

Contributed by:

S S

Zone maintenance

Re-sign an updated zone

Roll over DNSSEC keys

Prepublish key rollover

Double signature key rollover

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