"syslog-ng could not retrieve CRL" error seen after configuring syslog via transport method SSL

"syslog-ng could not retrieve CRL" error seen after configuring syslog via transport method SSL

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Created On 02/23/23 09:23 AM - Last Modified 04/21/25 07:37 AM


Symptom


  • After setting up syslog forwarding over SSL, the connection is failing with the below system log message:
Syslog connection failed to server['AF_INET.xxxxx:10514.']
Syslog connection broken to server['AF_INET.xxxxx:10514.']
  • More detailed logs can be seen in syslog-ng.log:
PA-5220> tail follow yes mp-log syslog-ng.log
Sep 3 13:23:18 fw01 syslog-ng[13884]: syslog-ng could not retrieve CRL; idx='0', rt1='1792', URI='http://crl.xxxxx.com/AAACertificateServices.crl'

 

 


Environment


  • Palo Alto Firewall.
  • PAN-OS 9.1 and above.
  • Syslog


Cause


The error message in syslog-ng.log can appear in two scenarios:

  • When CRL server is not reachable.
  • When CRL server is reachable, but in CRL response there is no CRL list present.
     


Resolution


  1. Ensure that the CRL server is reachable via the management interface of the firewall.
  2. Ping command may be used to check for connectivity:
PA-5220> ping host <CRL_Server_IP>
PING <CRL_Server_IP> 56(84) bytes of data.
64 bytes from <CRL_Server_IP>: icmp_seq=1 ttl=117 time=2.74 ms
64 bytes from <CRL_Server_IP>: icmp_seq=2 ttl=117 time=2.69 ms
  1. Netstat command can be used to check if connection is established:
PA-5220> show netstat numeric yes programs yes | match <CRL_Server_IP>
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 <FW_IP>:2049          <CRL_Server_IP>:80      ESTABLISHED

Note:



Additional Information


  • Setting a CRL Status service route for syslog is not supported. CRL Status service route is meant mainly for PAN-OS while the functionality for syslog depends on the syslog-ng lib.
  • Even if there is a service route configured for syslog to send via the dataplane interface, the CRL request will still be initiated via the management interface.

    How To Setup Syslog Monitoring Over TLS


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