On the BIND 9.x server, the private key corresponding to the zone signing key (ZSK), stored on name servers accepting dynamic updates, must be owned by named.

The private keys in the key signing key (KSK) and ZSK key pairs must be protected from unauthorized access. If possible, the private keys should be stored offline (with respect to the internet-facing, DNSSEC-aware name server) in a physically secure, nonnetwork-accessible machine along with the zone file primary copy.

This strategy is not feasible in situations in which the DNSSEC-aware name server has to support dynamic updates. To support dynamic update transactions, the DNSSEC-aware name server (which usually is a primary authoritative name server) has to have both the zone file primary copy and the private key corresponding to the zone-signing key (ZSK-private) online to immediately update the signatures for the updated RRsets. The private key corresponding to the key-signing key (KSK-private) can still be kept offline.

Note: This check only verifies for ZSK key file ownership. Permissions for key files are required under BIND-9X-001132 and BIND-9X-001142.

For each signed zone file, identify the ZSK "key id" number:

# cat <signed_zone_file> | grep -i "zsk" ZSK; alg = ECDSAP256SHA256; key id = 22335

Using the ZSK "key id", identify the private ZSK:

Kexample.com.+008+22335.private

Verify that the private ZSK is owned by named:

# ls -l <ZSK_key_file> -r------- 1 named named 1776 Jul 3 17:56 Kexample.com.+008+22335.private

If the key file is not owned by named, this is a finding.

Change the ownership of the ZSK private key to the root account:

# chown named <key_file>