Symptom
The system crashes. After the crash, multiple messages each 5 seconds appear in the Syslogs, as follows:
%PKI-3-CRL_FETCH_FAIL: CRL fetch for trustpoint DNAC-CA failed
Reason : Failed to select socket. Timeout : 5 (Connection timed out)
The router is unable to fetch a CRL from the DNAC-CA trustpoint and faces a timeout of 5 seconds.
or
%PKI-3-CRL_FETCH_FAIL: CRL fetch for trustpoint DNAC-CA failed
Reason : Enrollment URL not configured
Conditions
This issue was found on an ISR 4K running 17.5.1a (others may apply). A DNAC-CA trustpoint was configured, containing a certificate that refers to a CRL Distribution Point (CDP), however the device was unable to download the CRL from the CDP, as indicated by the %PKI-3-CRL_FETCH_FAIL errors.
Example of the affected configuration:
crypto pki trustpoint DNAC-CA
enrollment mode ra
enrollment terminal
usage ssl-client
revocation-check crl none <<<<<<<<<<<<<<
Workaround
There are multiple potential workarounds:
Workaround1:
Make sure the CDP is reachable from the device, so the CRL download does not fail.
Workaround2:
If using Cisco DNA Center 2.3.4.0 or later to manage the device, follow these steps to disable the CRL check:
1) In the Cisco DNA Center GUI navigate to Design > Network Settings > Security and Trust, and select "Revocation - Check: None" from the dropdown.
2) Navigate to Provision > Inventory, select the device, and select Actions > Telemetry > Update Telemety Settings ; make sure the "Force Configuration Push" checkbox is checked, click Next, optionally choose when to deploy the change, and click Apply.
Workaround 3:
If the device is managed by Cisco DNA Center 2.3.3.x or older, or is not managed by Cisco DNA Center, then manually disable the CRL check on the device:
crypto pki trustpoint DNAC-CA
revocation-check none
PLEASE NOTE: disabling the CRL check may weaken security. If the Cisco DNA Center certificate gets revoked and is placed on the CRL, the device will not be aware of this and will still consider the certificate as valid.
Check fixed releases - bug is resolved in 17.6.6
