Certificate Revocation List (CRL)
Each certificate authority (CA) periodically issues
a certificate revocation list (CRL) to a public repository. The
CRL identifies revoked certificates by serial number. After the
CA revokes a certificate, the next CRL update will include the serial
number of that certificate. The firewall supports CRLs in Distinguished Encoding
Rules (DER) and Privacy Enhanced Mail (PEM) formats.
The Palo Alto Networks firewall downloads and caches the last-issued
CRL for every CA listed in the trusted CA list of the firewall.
Caching only applies to validated certificates; if a firewall never
validated a certificate, the firewall cache does not store the CRL
for the issuing CA. Also, the cache only stores a CRL until it expires.
If you configure multiple CRL distribution points (CDPs) and
the firewall cannot reach the first CDP, the firewall does not check
the remaining CDPs. To redirect invalid CRL requests,
configure a DNS proxy as
an alternate server.
To use CRLs to verify the revocation status of certificates that authenticate users and devices,
configure a certificate profile and assign it to the interfaces that are specific to the
application: Authentication Portal, GlobalProtect (remote user-to-site or large scale),
site-to-site IPSec VPN, or web interface access to Palo Alto Networks firewalls or
Panorama. For details, see
Configure Revocation
Status Verification of Certificates.
