# Auditing

Auditing allows administrators to track
and log user activity on a MongoDB server.
With auditing enabled, the server will generate an audit log file.
This file contains information about different user events
including authentication, authorization failures, and so on.

To enable audit logging, specify where to send audit events
using the [`--auditDestination`](#-auditdestination) option on the command line
or the `auditLog.destination` variable in the configuration file.

If you want to output events to a file,
also specify the format of the file
using the [`--auditFormat`](#-auditformat) option
or the `auditLog.format` variable,
and the path to the file using the [`--auditPath`](#-auditpath) option
or the `auditLog.path` variable.

To filter recorded events, use the [`--auditFilter`](#-auditfilter) option
or the `auditLog.filter` variable.

For example, to log only events from a user named **tim**
and write them to a JSON file `/var/log/psmdb/audit.json`,
start the server with the following parameters:

```{.bash data-prompt="$"}
$ mongod \
 --dbpath data/db
 --auditDestination file \
 --auditFormat JSON \
 --auditPath /var/log/psmdb/audit.json \
 --auditFilter '{ "users.user" : "tim" }'
```

The options in the previous example can be used as variables
in the MongoDB configuration file:

```yaml
storage:
  dbPath: data/db
auditLog:
  destination: file
  format: JSON
  path: /var/log/psmdb/audit.json
  filter: '{ "users.user" : "tim" }'
```

This example shows how to send audit events to the
`syslog`. Specify the following parameters:

```{.bash data-prompt="$"}
mongod \
--dbpath data/db
--auditDestination syslog \
```

Alternatively, you can edit the MongoDB configuration file:

```yaml
storage:
 dbPath: data/db
auditLog:
 destination: syslog
```

!!! note 
 
    If you start the server with auditing enabled, you cannot disable auditing dynamically during runtime.

## Audit options

The following options control audit logging:

| Command line          | Configuration file     | Type   | Description  |
| --------------------- | ---------------------- | ------ | ------------ |
| `--auditDestination()`| `auditLog.destination` | string | Enables auditing and specifies where to send audit events: <br> - `console`: Output audit events to `stdout`. <br> - `file`: Output audit events to a file specified by the `--auditPath` option in a format specified by the `--auditFormat` option. <br> - `syslog`: Output audit events to `syslog`|
| `--auditFilter()`    | `auditLog.filter`       | string | Specifies a filter to apply to incoming audit events, enabling the administrator to only capture a subset of them. The value must be interpreted as a query object with the following syntax: <br><br>`{ <field1>: <expression1>, ... }` <br><br> Audit log events that match this query will be logged. Events that do not match this query will be ignored. <br> For more information, see [Audit filter examples](#audit-file-examples)|
| `--auditFormat()`    | `auditLog.format`       | string | Specifies the format of the audit log file, if you set the `--auditDestination` option to `file`. <br> The default value is `JSON`. Alternatively, you can set it to `BSON`|
| `--auditPath()`      | `auditLog.path`         | string | Specifies the fully qualified path to the file where audit log events are written, if you set the `--auditDestination` option to `file`. <br> If this option is not specified, then the `auditLog.json` file is created in the server’s configured log path. If log path is not configured on the server, then the `auditLog.json` file is created in the current directory (from which `mongod` was started). <br><br> **NOTE**: This file will rotate in the same manner as the system log path, either on server reboot or using the `logRotate` command. The time of rotation will be added to the old file’s name.

## Audit message syntax

Audit logging writes messages in JSON format with the following syntax:

```javascript
{
  atype: <String>,
  ts : { "$date": <timestamp> },
  local: { ip: <String>, port: <int> },
  remote: { ip: <String>, port: <int> },
  users : [ { user: <String>, db: <String> }, ... ],
  roles: [ { role: <String>, db: <String> }, ... ],
  param: <document>,
  result: <int>
}
```

| Parameter | Description            |
| --------- | ---------------------- |
| `atype`   | Event type             |
| `ts`      | Date and UTC time of the event|
| `local`   | Local IP address and port number of the instance | 
| `remote`  | Remote IP address and port number of the incoming connection associated with the event | 
| `users`   | Users associated with the event |
| `roles`   | Roles granted to the user | 
| `param`   | Details of the event associated with the specific type |
| `result`  | Exit code (`0` for success) |

## Audit filter examples

The following examples show the flexibility of audit log filters.

```yaml
auditLog:
   destination: file
      filter: '{atype: {$in: [
         "authenticate", "authCheck",
         "renameCollection", "dropCollection", "dropDatabase",
         "createUser", "dropUser", "dropAllUsersFromDatabase", "updateUser",
         "grantRolesToUser", "revokeRolesFromUser", "createRole", "updateRole",
         "dropRole", "dropAllRolesFromDatabase", "grantRolesToRole", "revokeRolesFromRole",
         "grantPrivilegesToRole", "revokePrivilegesFromRole",
         "replSetReconfig",
         "enableSharding", "shardCollection", "addShard", "removeShard",
         "shutdown",
         "applicationMessage"
      ]}}'
```

### Standard query selectors

You can use query selectors,
such as `$eq`, `$in`, `$gt`, `$lt`, `$ne`, and others
to log multiple event types.

For example, to log only the `dropCollection` and `dropDatabase` events:


=== "Command line" 

     ```bash
     --auditDestination file --auditFilter '{ atype: { $in: [ "dropCollection", "dropDatabase" ] } }'
     ```

=== "Config file"

     ```yaml
     auditLog:
       destination: file
       filter: '{ atype: { $in: [ "dropCollection", "dropDatabase" ] } }'
     ```

### Regular expressions

Another way to specify multiple event types is using regular expressions.

For example, to filter all `drop` operations:


=== "Command line"

     ```bash
     --auditDestination file --auditFilter '{ "atype" : /^drop.*/ }'
     ```

=== "Config file"

     ```yaml
     auditLog:
       destination: file
       filter: '{ "atype" : /^drop.*/ }'
     ```

### Read and write operations

By default, operations with successful authorization are not logged,
so for this filter to work, enable `auditAuthorizationSuccess` parameter,
as described in [Enabling auditing of authorization success](#enabling-auditing-of-authorization-success).

For example, to filter read and write operations
on all the collections in the `test` database:

!!! note 

    The dot (`.`) after the database name in the regular expression must be escaped with two backslashes (`\\\\`).


=== "Command line"

     ```bash
     --setParameter auditAuthorizationSuccess=true --auditDestination file --auditFilter '{ atype: "authCheck", "param.command": { $in: [ "find", "insert", "delete", "update", "findandmodify" ] }, "param.ns": /^test\\./ } }'
     ```


=== "Config file"

     ```yaml
     auditLog:
       destination: file
       filter: '{ atype: "authCheck", "param.command": { $in: [ "find", "insert", "delete", "update", "findandmodify" ] }, "param.ns": /^test\\./ } }'

     setParameter: { auditAuthorizationSuccess: true }
     ```

## Enabling auditing of authorization success

By default, the audit system logs only authorization failures for the `authCheck` action. The `authCheck` action refers to the operations a user is or is not authorized to perform on the server according to the privileges outlined in the roles assigned to the user.

To enable logging of authorization successes,
set the `auditAuthorizationSuccess` parameter to `true`. Audit events
will then be triggered by every command that requires authorization, including CRUD ones.

!!! warning 

    Enabling the `auditAuthorizationSuccess` parameter heavily impacts the performance compared to logging only authorization failures.

You can enable it on a running server using the following command:

```javascript
db.adminCommand( { setParameter: 1, auditAuthorizationSuccess: true } )
```

To enable it on the command line, use the following option
when running `mongod` or `mongos` process:

```javascript
--setParameter auditAuthorizationSuccess=true
```

You can also add it to the configuration file as follows:

```yaml
setParameter:
  auditAuthorizationSuccess: true
```

??? example "Example of the audit message"

    ```json
    {
      "atype": "authCheck",
      "ts": {
        "$date": "2024-03-13T06:28:04.631-04:00"
      },
      "local": {
        "ip": "172.17.0.2",
        "port": 20040
      },
      "remote": {
        "ip": "127.0.0.1",
        "port": 52128
      },
      "users": [
        {
          "user": "admin",
          "db": "admin"
        }
      ],
      "roles": [
        {
          "role": "clusterAdmin",
          "db": "admin"
        },
        {
          "role": "readWriteAnyDatabase",
          "db": "admin"
        },
        {
          "role": "userAdminAnyDatabase",
          "db": "admin"
        }
      ],
      "param": {
        "command": "insert",
        "ns": "audit_authz_insert.foo",
        "args": {
          "insert": "foo",
          "ordered": true,
          "lsid": {
            "id": {
              "$binary": "nfnnHQo0RDOtI6722FlP5w==",
              "$type": "04"
            }
          },
          "$db": "audit_authz_insert"
        }
      },
      "result": 0
    }
    ```