auditd.conf

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



NAME
       auditd.conf - audit daemon configuration file

DESCRIPTION
       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/analized 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.

       disp_qos
              This option controls whether you want blocking/lossless or non-
              blocking/lossy communication between the audit daemon and the
              dispatcher. There is a 128k buffer between the audit daemon and
              dispatcher. This is good enough for most uses. If lossy is
              chosen, incoming events going to the dispatcher are discarded
              when this queue is full. (Events are still written to disk if
              log_format is not nolog.) Otherwise the auditd daemon will wait
              for the queue to have an empty spot before logging to disk. The
              risk is that while the daemon is waiting for network IO, an
              event is not being recorded to disk. Valid values are: lossy and
              lossless. Lossy is the default value.

       dispatcher
              The dispatcher is a program that is started by the audit daemon
              when it starts up. It will pass a copy of all audit events to
              that application's stdin. Make sure you trust the application
              that you add to this line since it runs with root privileges.

       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
              This is a numeric value in megabytes that tells the audit daemon
              when to perform a configurable action because the system is
              starting to run low on disk space. You may also append a percent
              sign (e.g. 5%) to the number to have the audit daemon calculate
              the number based on the disk partition size.

       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.

       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.

       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.

       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.

       enable_krb5
              If set to "yes", Kerberos 5 will be used for authentication and
              encryption.  The default is "no".

       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".


NOTES
       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.


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


SEE ALSO
       auditd(8), audisp-remote.conf(5).


AUTHOR
       Steve Grubb



Red Hat                           April 2016                   AUDITD.CONF:(5)