auditd.conf(5) — Linux manual page

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AUDITD.CONF:(5)      System Administration Utilities     AUDITD.CONF:(5)

NAME         top

       auditd.conf - audit daemon configuration file

DESCRIPTION         top

       The file /etc/audit/auditd.conf contains configuration
       information specific to the audit daemon. Each line should
       contain one configuration keyword, an equal sign, and then
       followed by appropriate configuration information. All option
       names and values are case insensitive. The keywords recognized
       are listed and described below. Each line should be limited to
       160 characters or the line will be skipped. You may add comments
       to the file by starting the line with a '#' character.

       local_events
              This yes/no keyword specifies whether or not to include
              local events. Normally you want local events so the
              default value is yes. Cases where you would set this to no
              is when you want to aggregate events only from the
              network. At the moment, this is useful if the audit daemon
              is running in a container. This option can only be set
              once at daemon start up. Reloading the config file has no
              effect.

       log_file
              This keyword specifies the full path name to the log file
              where audit records will be stored. It must be a regular
              file.

       write_logs
              This yes/no keyword determines whether or not to write
              logs to the disk.  Normally you want this so the default
              is yes.

       log_format
              The log format describes how the information should be
              stored on disk. There are 2 options: raw and enriched. If
              set to RAW, the audit records will be stored in a format
              exactly as the kernel sends it. The ENRICHED option will
              resolve all uid, gid, syscall, architecture, and socket
              address information before writing the event to disk. This
              aids in making sense of events created on one system but
              reported/analyzed on another system.  The NOLOG option is
              now deprecated. If you were setting this format, now you
              should set the write_logs option to no.

       log_group
              This keyword specifies the group that is applied to the
              log file's permissions. The default is root. The group
              name can be either numeric or spelled out.

       priority_boost
              This is a non-negative number that tells the audit daemon
              how much of a priority boost it should take. The default
              is 4. No change is 0.

       flush  Valid values are none, incremental, incremental_async,
              data,  and sync.  If set to none, no special effort is
              made to flush the audit records to disk. If set to
              incremental, Then the freq parameter is used to determine
              how often an explicit flush to disk is issued.  The
              incremental_async parameter is very much like incremental
              except the flushing is done asynchronously for higher
              performance. The data parameter tells the audit daemon to
              keep the data portion of the disk file sync'd at all
              times. The sync option tells the audit daemon to keep both
              the data and meta-data fully sync'd with every write to
              disk. The default value is incremental_async.

       freq   This is a non-negative number that tells the audit daemon
              how many records to write before issuing an explicit flush
              to disk command. This value is only valid when the flush
              keyword is set to incremental or incremental_async.

       num_logs
              This keyword specifies the number of log files to keep if
              rotate is given as the max_log_file_action.  If the number
              is < 2, logs are not rotated. This number must be 999 or
              less.  The default is 0 - which means no rotation. As you
              increase the number of log files being rotated, you may
              need to adjust the kernel backlog setting upwards since it
              takes more time to rotate the files. This is typically
              done in /etc/audit/audit.rules. If log rotation is
              configured to occur, the daemon will check for excess logs
              and remove them in effort to keep disk space available.
              The excess log check is only done on startup and when a
              reconfigure results in a space check.

       name_format
              This option controls how computer node names are inserted
              into the audit event stream. It has the following choices:
              none, hostname, fqd, numeric, and user.  None means that
              no computer name is inserted into the audit event.
              hostname is the name returned by the gethostname syscall.
              The fqd means that it takes the hostname and resolves it
              with dns for a fully qualified domain name of that
              machine.  Numeric is similar to fqd except it resolves the
              IP address of the machine. In order to use this option,
              you might want to test that 'hostname -i' or 'domainname
              -i' returns a numeric address. Also, this option is not
              recommended if dhcp is used because you could have
              different addresses over time for the same machine.  User
              is an admin defined string from the name option. The
              default value is none.

       name   This is the admin defined string that identifies the
              machine if user is given as the name_format option.

       max_log_file
              This keyword specifies the maximum file size in megabytes.
              When this limit is reached, it will trigger a configurable
              action. The value given must be numeric.

       max_log_file_action
              This parameter tells the system what action to take when
              the system has detected that the max file size limit has
              been reached. Valid values are ignore, syslog, suspend,
              rotate and keep_logs.  If set to ignore, the audit daemon
              does nothing.  syslog means that it will issue a warning
              to syslog.  suspend will cause the audit daemon to stop
              writing records to the disk. The daemon will still be
              alive. The rotate option will cause the audit daemon to
              rotate the logs. It should be noted that logs with higher
              numbers are older than logs with lower numbers. This is
              the same convention used by the logrotate utility. The
              keep_logs option is similar to rotate except it does not
              use the num_logs setting. This prevents audit logs from
              being overwritten. The effect is that logs accumulate and
              are not deleted - which will trigger the space_left_action
              if the volume fills up. This is best used in combination
              with an external script used to archive logs on a periodic
              basis.

       verify_email
              This option determines if the email address given in
              action_mail_acct is checked to see if the domain name can
              be resolved. This option must be given before
              action_mail_acct or the default value of yes will be used.

       action_mail_acct
              This option should contain a valid email address or alias.
              The default address is root. If the email address is not
              local to the machine, you must make sure you have email
              properly configured on your machine and network. Also,
              this option requires that /usr/lib/sendmail exists on the
              machine.

       space_left
              If the free space in the filesystem containing log_file
              drops below this value, the audit daemon takes the action
              specified by space_left_action.  If the value of
              space_left is specified as a whole number, it is
              interpreted as an absolute size in megabytes (MiB).  If
              the value is specified as a number between 1 and 99
              followed by a percentage sign (e.g., 5%), the audit daemon
              calculates the absolute size in megabytes based on the
              size of the filesystem containing log_file.  (E.g., if the
              filesystem containing log_file is 2 gigabytes in size, and
              space_left is set to 25%, then the audit daemon sets
              space_left to approxiatemly 500 megabytes.  Note that this
              calculation is performed when the audit daemon starts, so
              if you resize the filesystem containing log_file while the
              audit daemon is running, you should send the audit daemon
              SIGHUP to re-read the configuration file and recalculate
              the correct percentage.

       space_left_action
              This parameter tells the system what action to take when
              the system has detected that it is starting to get low on
              disk space.  Valid values are ignore, syslog, rotate,
              email, exec, suspend, single, and halt.  If set to ignore,
              the audit daemon does nothing.  syslog means that it will
              issue a warning to syslog.  rotate will rotate logs,
              losing the oldest to free up space.  Email means that it
              will send a warning to the email account specified in
              action_mail_acct as well as sending the message to syslog.
              exec /path-to-script will execute the script. You cannot
              pass parameters to the script. The script is also
              responsible for telling the auditd daemon to resume
              logging once its completed its action. This can be done by
              adding service auditd resume to the script.  suspend will
              cause the audit daemon to stop writing records to the
              disk. The daemon will still be alive. The single option
              will cause the audit daemon to put the computer system in
              single user mode. The halt option will cause the audit
              daemon to shutdown the computer system. Except for rotate,
              it will perform this action just one time.

       admin_space_left
              This is a numeric value in megabytes that tells the audit
              daemon when to perform a configurable action because the
              system is running low on disk space. This should be
              considered the last chance to do something before running
              out of disk space. The numeric value for this parameter
              should be lower than the number for space_left. You may
              also append a percent sign (e.g. 1%) to the number to have
              the audit daemon calculate the number based on the disk
              partition size.

       admin_space_left_action
              This parameter tells the system what action to take when
              the system has detected that it is low on disk space.
              Valid values are ignore, syslog, rotate, email, exec,
              suspend, single, and halt.  If set to ignore, the audit
              daemon does nothing.  Syslog means that it will issue a
              warning to syslog.  rotate will rotate logs, losing the
              oldest to free up space.  Email means that it will send a
              warning to the email account specified in action_mail_acct
              as well as sending the message to syslog.  exec /path-to-
              script will execute the script. You cannot pass parameters
              to the script. The script is also responsible for telling
              the auditd daemon to resume logging once its completed its
              action. This can be done by adding service auditd resume
              to the script.  Suspend will cause the audit daemon to
              stop writing records to the disk. The daemon will still be
              alive. The single option will cause the audit daemon to
              put the computer system in single user mode. The halt
              option will cause the audit daemon to shutdown the
              computer system. Except for r otate, it will perform this
              action just one time.

       disk_full_action
              This parameter tells the system what action to take when
              the system has detected that the partition to which log
              files are written has become full. Valid values are
              ignore, syslog, rotate, exec, suspend, single, and halt.
              If set to ignore, the audit daemon will issue a syslog
              message but no other action is taken.  Syslog means that
              it will issue a warning to syslog.  rotate will rotate
              logs, losing the oldest to free up space.  exec /path-to-
              script will execute the script. You cannot pass parameters
              to the script. The script is also responsible for telling
              the auditd daemon to resume logging g once its completed
              its action. This can be done by adding service auditd
              resume to the script.  Suspend will cause the audit daemon
              to stop writing records to the disk. The daemon will still
              be alive. The single option will cause the audit daemon to
              put the computer system in single user mode.  halt option
              will cause the audit daemon to shutdown the computer
              system.

       disk_error_action
              This parameter tells the system what action to take
              whenever there is an error detected when writing audit
              events to disk or rotating logs. Valid values are ignore,
              syslog, exec, suspend, single, and halt.  If set to
              ignore, the audit daemon will not take any action.  Syslog
              means that it will issue no more than 5 consecutive
              warnings to syslog.  exec /path-to-script will execute the
              script. You cannot pass parameters to the script.  Suspend
              will cause the audit daemon to stop writing records to the
              disk. The daemon will still be alive. The single option
              will cause the audit daemon to put the computer system in
              single user mode.  halt option will cause the audit daemon
              to shutdown the computer system.

       tcp_listen_port
              This is a numeric value in the range 1..65535 which, if
              specified, causes auditd to listen on the corresponding
              TCP port for audit records from remote systems. The audit
              daemon may be linked with tcp_wrappers. You may want to
              control access with an entry in the hosts.allow and deny
              files. If this is deployed on a systemd based OS, then you
              may need to adjust the 'After' directive. See the note in
              the auditd.service file.

       tcp_listen_queue
              This is a numeric value which indicates how many pending
              (requested but unaccepted) connections are allowed.  The
              default is 5.  Setting this too small may cause
              connections to be rejected if too many hosts start up at
              exactly the same time, such as after a power failure. This
              setting is only used for aggregating servers. Clients
              logging to a remote server should keep this commented out.

       tcp_max_per_addr
              This is a numeric value which indicates how many
              concurrent connections from one IP address is allowed.
              The default is 1 and the maximum is 1024. Setting this too
              large may allow for a Denial of Service attack on the
              logging server. Also note that the kernel has an internal
              maximum that will eventually prevent this even if auditd
              allows it by config. The default should be adequate in
              most cases unless a custom written recovery script runs to
              forward unsent events. In this case you would increase the
              number only large enough to let it in too.

       use_libwrap
              This setting determines whether or not to use tcp_wrappers
              to discern connection attempts that are from allowed
              machines. Legal values are either yes, or no The default
              value is yes.

       tcp_client_ports
              This parameter may be a single numeric value or two values
              separated by a dash (no spaces allowed).  It indicates
              which client ports are allowed for incoming connections.
              If not specified, any port is allowed.  Allowed values are
              1..65535.  For example, to require the client use a
              priviledged port, specify 1-1023 for this parameter. You
              will also need to set the local_port option in the audisp-
              remote.conf file. Making sure that clients send from a
              privileged port is a security feature to prevent log
              injection attacks by untrusted users.

       tcp_client_max_idle
              This parameter indicates the number of seconds that a
              client may be idle (i.e. no data from them at all) before
              auditd complains. This is used to close inactive
              connections if the client machine has a problem where it
              cannot shutdown the connection cleanly. Note that this is
              a global setting, and must be higher than any individual
              client heartbeat_timeout setting, preferably by a factor
              of two.  The default is zero, which disables this check.

       transport
              If set to TCP, only clear text tcp connections will be
              used. If set to KRB5, then Kerberos 5 will be used for
              authentication and encryption. The default value is TCP.

       enable_krb5
              This option is deprecated. Use the transport option above
              instead. If set to "yes", Kerberos 5 will be used for
              authentication and encryption.  The default is "no". If
              this option is set to "yes" and it follows the transport
              option, it will override the transport setting. This would
              be the normal expected behavior for backwards
              compatibility.

       krb5_principal
              This is the principal for this server.  The default is
              "auditd".  Given this default, the server will look for a
              key named like auditd/hostname@EXAMPLE.COM stored in
              /etc/audit/audit.key to authenticate itself, where
              hostname is the canonical name for the server's host, as
              returned by a DNS lookup of its IP address.

       krb5_key_file
              Location of the key for this client's principal.  Note
              that the key file must be owned by root and mode 0400.
              The default is /etc/audit/audit.key

       distribute_network
              If set to "yes", network originating events will be
              distributed to the audit dispatcher for processing. The
              default is "no".

       q_depth
              This is a numeric value that tells how big to make the
              internal queue of the audit event dispatcher. A bigger
              queue lets it handle a flood of events better, but could
              hold events that are not processed when the daemon is
              terminated. If you get messages in syslog about events
              getting dropped, increase this value. The default value is
              400.

       overflow_action
              This option determines how the daemon should react to
              overflowing its internal queue. When this happens, it
              means that more events are being received than it can pass
              along to child processes. This error means that it is
              going to lose the current event that it's trying to
              dispatch. This option has the following choices: ignore,
              syslog, suspend, single, and halt.  If set to ignore, the
              audit daemon does nothing.  syslog means that it will
              issue a warning to syslog.  suspend will cause the audit
              daemon to stop sending events to child processes. The
              daemon will still be alive. The single option will cause
              the audit daemon to put the computer system in single user
              mode.  halt option will cause the audit daemon to shutdown
              the computer system.

       max_restarts
              This is a non-negative number that tells the audit event
              dispatcher how many times it can try to restart a crashed
              plugin. The default is 10.

       plugin_dir
              This is the location that auditd will use to search for
              its plugin configuration files.

       end_of_event_timeout
              This is a non-negative number of seconds used by the
              userspace auparse() library routines and the aureport(8) ,
              ausearch(8) utilities to consider an event is complete
              when parsing an event log stream. For an event stream
              being processed, if the time of the current event is over
              end_of_event_timeout seconds old, compared to co-located
              events, then the event is considered complete. See the
              NOTES section for more detail.

NOTES         top

       In a CAPP environment, the audit trail is considered so important
       that access to system resources must be denied if an audit trail
       cannot be created. In this environment, it would be suggested
       that /var/log/audit be on its own partition. This is to ensure
       that space detection is accurate and that no other process comes
       along and consumes part of it.

       The flush parameter should be set to sync or data.

       Max_log_file and num_logs need to be adjusted so that you get
       complete use of your partition. It should be noted that the more
       files that have to be rotated, the longer it takes to get back to
       receiving audit events. Max_log_file_action should be set to
       keep_logs.

       Space_left should be set to a number that gives the admin enough
       time to react to any alert message and perform some maintenance
       to free up disk space. This would typically involve running the
       aureport -t report and moving the oldest logs to an archive area.
       The value of space_left is site dependent since the rate at which
       events are generated varies with each deployment. The
       space_left_action is recommended to be set to email. If you need
       something like an snmp trap, you can use the exec option to send
       one.

       Admin_space_left should be set to the amount of disk space on the
       audit partition needed for admin actions to be recorded.
       Admin_space_left_action would be set to single so that use of the
       machine is restricted to just the console.

       The disk_full_action is triggered when no more room exists on the
       partition. All access should be terminated since no more audit
       capability exists. This can be set to either single or halt.

       The disk_error_action should be set to syslog, single, or halt
       depending on your local policies regarding handling of hardware
       malfunctions.

       Specifying a single allowed client port may make it difficult for
       the client to restart their audit subsystem, as it will be unable
       to recreate a connection with the same host addresses and ports
       until the connection closure TIME_WAIT state times out.

       Auditd events are made up of one or more records. The auditd
       system cannot guarantee that the set of records that make up an
       event will occur atomically, that is the stream will have
       interleaved records of different events, IE

              event0_record0
              event1_record0
              event2_record0
              event1_record3
              event2_record1
              event1_record4
              event3_record0

       The auditd system does not guarantee that the records that make
       up an event will appear in order. Thus, when processing event
       streams, we need to maintain a list of events with their own list
       of records hence List of List (LOL) event processing.

       When processing an event stream we define the end of an event via

              record type = AUDIT_EOE (audit end of event type record),
              or
              record type = AUDIT_PROCTITLE (we note the AUDIT_PROCTITLE
              is always the last record), or
              record type = AUDIT_KERNEL (kernel events are one record
              events), or
              record type < AUDIT_FIRST_EVENT (only single record events
              appear before this type), or
              record type >= AUDIT_FIRST_ANOM_MSG (only single record
              events appear after this type), or
              record type >= AUDIT_MAC_UNLBL_ALLOW && record type <=
              AUDIT_MAC_CALIPSO_DEL (these are also one record events),
              or
              for the stream being processed, the time of the event is
              over end_of_event_timeout seconds old.

FILES         top

       /etc/audit/auditd.conf
              Audit daemon configuration file

SEE ALSO         top

       auditd(8), audisp-remote.conf(5), auditd-plugins(5).

AUTHOR         top

       Steve Grubb

COLOPHON         top

       This page is part of the audit (Linux Audit) project.
       Information about the project can be found at 
       ⟨http://people.redhat.com/sgrubb/audit/⟩.  If you have a bug
       report for this manual page, send it to linux-audit@redhat.com.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/linux-audit/audit-userspace.git⟩ on
       2021-04-01.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-29.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

Red Hat                        August 2018               AUDITD.CONF:(5)

Pages that refer to this page: auparse_set_eoe_timeout(3)auditd-plugins(5)auditd(8)aureport(8)ausearch(8)