The file
/etc/audit/auditd.conf
contains configuration information specific to the audit daemon.
It should contain one configuration keyword per line, an equal sign,
and then followed by appropriate configuration information. The
keywords recognized are:
log_file, log_format, flush, freq, num_logs,
max_log_file, max_log_file_action, space_left,
action_mail_acct, space_left_action, admin_space_left,
admin_space_left_action,
disk_full_action, and disk_error_action.
These keywords are described below.
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.
log_format
The log format describes how the information should be stored on disk. There are 2 options: raw and nolog.
If set to
RAW,
the audit records will be stored in a format exactly as the kernel sends it. If this option is set to
NOLOG
then all audit information is discarded instead of writing to disk. This mode does not affect data sent to the audit event dispatcher.
priority_boost
This is a non-negative number that tells the audit damon how much of a priority boost it should take. The default is 3. No change is 0.
flush
Valid values are
none, incremental, 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
data
parameter tells the audit damon 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.
freq
This is a non-negative number that tells the audit damon 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.
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 99 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.
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.
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 enogh 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.
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.
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.
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, 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.
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.
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.
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.
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, 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.
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.
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
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, exec, suspend, single, and halt.
If set to
ignore,
the audit daemon does nothing.
Syslog
means that it will issue a warning 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.
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 does nothing.
Syslog
means that it will issue a warning 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.
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 dependant 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.
