Manage Logs

The following topic describes Tenable Agent log files. Agent log files are location in the following directories:

Operating System Log Location
Windows C:\ProgramData\Tenable\Nessus Agent\nessus\logs
Linux /opt/nessus_agent/var/nessus/logs
macOS /Library/NessusAgent/run/var/nessus/logs

nessusd.dump

nessusd.dump is the agent dump log file used for debugging output.

To configure nessusd.dump:

  1. Open the agent command line interface.

  2. Use the command # nessuscli fix --set setting=value to configure the following settings:

    Name

    		 Setting

    Description

    		 Default Valid Values
    Nessus Dump File Max Files dumpfile_max_files Sets the maximum number of the nessusd.dump files kept on disk. If the number exceeds the specified value, the setting deletes the oldest dump file. 100 Integers 1-1000
    Nessus Dump File Max Size dumpfile_max_size Sets the maximum size of the nessusd.dump files in MB. If the file size exceeds the maximum size, the setting creates a new dump file. 512 Integers 1-2048

    For more information, see Advanced Settings.

nessusd.messages

nessusd.messages is the agent message log.

To configure nessusd.messages:

  1. Open the agent command line interface.

  2. Use the command # nessuscli fix --set setting=value to configure the following settings:

    Name

    		 Setting

    Description

    		 Default Valid Values
    Log File Maximum Files logfile_max_files Determines the maximum number of nessusd.messages files that Tenable Agent keeps on the disk. If the number of nessusd.messages log files exceeds the specified value, Tenable Agent deletes the oldest log files.

    2

    Integers 1-1000
    Log File Maximum Size logfile_max_size Determines the maximum size of the nessusd.messages file in MB. If the file size exceeds the maximum size, Tenable Agent creates a new message log file.

    10

    		 Integers 1-2048

    For more information, see Advanced Settings.

backend.log

backend.log is the agent backend log.

You can configure log locations and rotation strategies for backend.log by editing the log.json file. You can also configure custom logs by creating a new reporters[x].reporter section and creating a custom file name.

To configure backend.log:

  1. Using a text editor, open the log.json file, located in the corresponding directory:

    • Windows — C:\ProgramData\Tenable\Nessus Agent\nessus\log.json

    • Linux — /opt/nessus_agent/var/nessus/log.json

    • macOS — /Library/NessusAgent/run/var/nessus/log.json

  2. For backend.log, edit or create a reporters[x].reporter section, and add or modify the following parameters:

    Parameter Default value Can be modified? Description
    tags

    log, info, warn, error, trace

    		yes

    Determines what log information the log includes.

    • response — Web server activity logs

    • info — Informational logs for a specific task
    • warn — Warning logs for a specific task
    • error — Error logs for a specific task
    • debug — Debugging output
    • verbose — debugging output with more information than debug
    • trace — Logs used to trace output
    type file not recommended Determines the type of the log file.
    rotation_strategy size yes

    Determines whether the log archives files based on maximum rotation size or rotation time.

    Valid values:

    • size — Rotate the log based on size, as specified in max_size.
    • daily — Rotate the log based on time, as specified in rotation_time.
    rotation_time 86400 (1 day) yes

    Rotation time in seconds.

    Only used if rotation_strategy is daily.

    max_size

    10485760 (10 MB)

    		 yes

    Rotation size in bytes.

    Only used if rotation_strategy is size.

    max_files

    2

    		 yes

    Maximum number of files allowed in the file rotation.

    The maximum number includes the main file, so 10 max_files is 1 main file and 9 backups. If you decrease this number, Tenable Nessus deletes the old logs.
    file

    Depends on the operating system and log file

    		 yes

    The location and name of the log file.

    If you change the name of a default Tenable Agent log file, some advanced settings may not be able to modify the log settings.

    context true not recommended Enables more context information for logs.
    format

    system

    		not recommended

    Determines the format of the output.

    • combined — Presents output in a format used for web server logs.
    • system — Presents output in the default operating system log format.

  3. Save the log.json file.

  4. Restart the agent service.

    The agent updates the log settings.

nessuscli.log

nessuscli.log contains a record of CLI events.