auditd - The Linux Audit daemon
auditd
[-f] [-l] [-n] [-s disable|enable|nochange] [-c <config_dir>]
auditd is the userspace component to the Linux Auditing
System. It's responsible for writing audit records to the disk. Viewing the
logs is done with the ausearch or aureport utilities.
Configuring the audit system or loading rules is done with the
auditctl utility. During startup, the rules in
/etc/audit/audit.rules are read by auditctl and loaded into
the kernel. Alternately, there is also an augenrules program that
reads rules located in /etc/audit/rules.d/ and compiles them into an
audit.rules file. The audit daemon itself has some configuration options
that the admin may wish to customize. They are found in the
auditd.conf file.
- -f
- leave the audit daemon in the foreground for debugging. Messages also go
to stderr rather than the audit log.
- -l
- allow the audit daemon to follow symlinks for config files.
- -n
- no fork. This is useful for running off of inittab or systemd.
- -s=ENABLE_STATE
- specify when starting if auditd should change the current value for the
kernel enabled flag. Valid values for ENABLE_STATE are
"disable", "enable" or "nochange". The
default is to enable (and disable when auditd terminates). The value of
the enabled flag may be changed during the lifetime of auditd using
'auditctl -e'.
- -c
- Specify alternate config file directory. Note that this same directory
will be passed to the dispatcher. (default: /etc/audit/)
- SIGHUP
- causes auditd to reconfigure. This means that auditd re-reads the
configuration file. If there are no syntax errors, it will proceed to
implement the requested changes. If the reconfigure is successful, a
DAEMON_CONFIG event is recorded in the logs. If not successful, error
handling is controlled by space_left_action, admin_space_left_action,
disk_full_action, and disk_error_action parameters in auditd.conf.
- SIGTERM
- caused auditd to discontinue processing audit events, write a shutdown
audit event, and exit.
- SIGUSR1
- causes auditd to immediately rotate the logs. It will consult the
max_log_file_action to see if it should keep the logs or not.
- SIGUSR2
- causes auditd to attempt to resume logging and passing events to plugins.
This is usually needed after logging has been suspended or the internal
queue is overflowed. Either of these conditions depends on the applicable
configuration settings.
- SIGCONT
- causes auditd to dump a report of internal state to /var/run/auditd.state.
- 1
- Cannot adjust priority, daemonize, open audit netlink, write the pid file,
start up plugins, resolve the machine name, set audit pid, or other
initialization tasks.
- 2
- Invalid or excessive command line arguments
- 4
- The audit daemon doesn't have sufficient privilege
- 6
- There is an error in the configuration file
/etc/audit/auditd.conf - configuration file for audit
daemon
/etc/audit/audit.rules - audit rules to be loaded at
startup
/etc/audit/rules.d/ - directory holding individual sets of
rules to be compiled into one file by augenrules.
/etc/audit/plugins.d/ - directory holding individual plugin
configuration files.
/etc/audit/audit-stop - These rules are loaded when the
audit daemon stops.
/var/run/auditd.state - report about internal state.
A boot param of audit=1 should be added to ensure that all
processes that run before the audit daemon starts is marked as auditable by
the kernel. Not doing that will make a few processes impossible to properly
audit.
The audit daemon can receive audit events from other audit daemons
via the audisp-remote plugin. The audit daemon may be linked with
tcp_wrappers to control which machines can connect. If this is the case, you
can add an entry to hosts.allow and deny.
auditd.conf(5), auditd-plugins(5),
ausearch(8), aureport(8), auditctl(8),
augenrules(8), audit.rules(7).