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Working with Filter Node Logs

Where Filter Node Logs are Stored

A filter node stores the following log files in the /var/log/wallarm directory:

  • brute-detect.log and sync-brute-clusters.log: the log of fetching the brute force attack-related counters in the filter node cluster.

  • export-attacks.log: the log of exporting the attacks' data from the postanalytics module to the Wallarm cloud.

  • export-clusterization-data.log: the log of exporting the filter node cluster's data.

  • export-counters.log: the log of exporting the counters' data (see “Monitoring the Filter Node”).

  • sync-markers.log: the log of fetching the markers from the Wallarm cloud.

  • syncnode.log: the log of syncing the filter node with the Wallarm cloud (this includes fetching the LOM and proton.db files from the cloud).

  • tarantool.log: the log of the postanalytics module operations.

Configuring Extended Logging for the NGINX‑Based Filter Node

NGINX writes logs of the processed requests (access logs) into a separate log file, using the predefined combined logging format by default.

log_format combined '$remote_addr - $remote_user [$time_local] '
                    '"$request" $request_id $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent"';

You can define and use a custom logging format by including one or several filter node variables (as well as other NGINX variables if needed). The NGINX log file will allow for much faster filter node diagnostics.

Filter Node Variables

You may use the following filter node variables when defining the NGINX logging format:

Name Type Value
request_id String Request identifier
Has the following value form: a79199bcea606040cc79f913325401fb
wallarm_request_time Float Request execution time in seconds
wallarm_serialized_size Integer Size of the serialized request in bytes
wallarm_is_input_valid Integer Request validity
0: request is valid. The request has been checked by filter node and matches LOM rules.
1: request is invalid. The request has been checked by filter node and does not match LOM rules.
wallarm_attack_type Integer Attack types represented in the request in bit string format
0x00000000: no attack: "0"
0x00000001: agressive mode flag: "1"
0x00000002: xss: "2"
0x00000004: sqli: "4"
0x00000008: rce: "8"
0x00000010: xxe: "16"
0x00000020: ptrav: "32"
0x00000040: crlf: "64"
0x00000080: redir: "128"
0x00000100: nosqli: "256"
0x00000200: infoleak: "512"
0x00001000: marker: "4096"
0x20000000: overlimit_res: "536870912"
0x40000000: zip_bomb: "1073741824"
0x80000000: vpatch: "2147483648"

Configuration Example

Let us assume that you need to specify the extended logging format named wallarm_combined that includes the following variables:

  • all variables used in the combined format

  • all filter node variables

To do this, perform the following actions:

  1. The lines below describe the desired logging format. Add them into the http block of the NGINX configuration file.

    log_format wallarm_combined '$remote_addr - $remote_user [$time_local] '
                                '"$request" $request_id $status $body_bytes_sent '
                                '"$http_referer" "$http_user_agent"'
                                '$wallarm_request_time $wallarm_serialized_size $wallarm_is_input_valid $wallarm_attack_type';
  2. Enable the extended logging format by adding the following directive into the same block as in the first step:

    access_log /var/log/nginx/access.log wallarm_combined;

    Processed request logs will be written in the wallarm_combined format into the /var/log/nginx/access.log file.

    Conditional Logging

    With the directive listed above, all processed requests will be logged to a log file, including these that are not related to an attack.

    You can configure conditional logging to write logs only for the requests that are part of an attack (the wallarm_attack_type variable value is not zero for these requests). To do so, add a condition to the aforementioned directive: access_log /var/log/nginx/access.log wallarm_combined if=$wallarm_attack_type;

    This may be useful if you want to reduce a log file size, or if you integrate a filter node with one of SIEM solutions.

  3. Restart NGINX by running one of the following commands depending on the OS you are using:

    sudo systemctl restart nginx
    sudo service nginx restart
    sudo systemctl restart nginx

Detailed information

To see detailed information about configuring logging in NGINX, proceed to this link.