NGINX App Protect WAF Access Log

Learn about the NGINX App Protect WAF Access Log Request Mechanism.

Access Logs

Access log is NGINX’s request log mechanism. It is controlled by two directives.

log_format

This directive determines the format of the log messages using predefined variables. App Protect will enrich this set of variables with several security log attributes that are available to be included in the log_format. If log_format is not specified then the built-in format combined is used but, because that format does not include the extended App Protect variables, this directive must be used when the user wants to add App Protect information to the log.

access_log

This directive determines the destination of the access_log and the name of the format. The default is the file /etc/nginx/log/access.log using the combined format. In order to use the custom format that includes the NAP variables, use this directive with the name of the desired format.

App Protect Variables for Access Log

These are the variables added to Access Log. They are a subset of the Security log attributes. The Security log names are prefixed with $app_protect.

Name Meaning Comment
$app_protect_support_id Unique ID assigned to the request by App Protect. To be used to correlate the access log with the security log.
Left empty in failure mode.
$app_protect_outcome One of:
  • PASSED: request was sent to origin server.
  • REJECTED: request was blocked.
$app_protect_outcome_reason One of:
  • SECURITY_WAF_OK: allowed with no violations (legal request).
  • SECURITY_WAF_VIOLATION: blocked due to security violations.
  • SECURITY_WAF_FLAGGED: allowed although it has violations (illegal).
  • SECURITY_WAF_BYPASS: WAF was supposed to inspect the request but it didn’t (because of unavailability or resource shortage). The request was PASSED or REJECTED according to the failure mode action determined by the user.
  • SECURITY_WAF_REQUEST_IN_FILE_BYPASS: WAF was supposed to inspect the request but it didn’t (because request buffer was full and request was written to file). The request was PASSED or REJECTED according to the failure mode action determined by the user.
  • SECURITY_WAF_COMPRESSED_REQUEST_BYPASS: WAF was supposed to inspect the request but it didn’t (because request was compressed). The request was PASSED or REJECTED according to the failure mode action determined by the user.
$app_protect_policy_name The name of the policy that enforced the request.
$app_protect_version The App Protect version string: major.minor.build format. Does not include the NGINX plus version (e.g. R21). The latter is available in $version variable.

Note that many of the other Security log attributes that are not included here have exact or similar parallels among the NGINX variables also available for access log. For example, $request is parallel to the request security log attribute. See the full list of NGINX variables.

Example

http {
    log_format security_waf 'request_time=$request_time client_ip=$remote_addr,'
                             'request="$request", status=$status,'
                             'waf_policy=$app_protect_policy_name, waf_request_id=$app_protect_support_id'
                             'waf_action=$app_protect_outcome, waf_action_reason=$app_protect_outcome_reason';

    server {

        location / {
            access_log /etc/app_protect/logs/nginx-access.log security_waf;
            ...
        }
    }
}

This documentation applies to the following versions of NGINX App Protect WAF: 3.12.