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NAME | DESCRIPTION | NOTES | FILES | SEE ALSO | AUTHOR | COLOPHON |
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AUDITD.CONF(5) System Administration Utilities AUDITD.CONF(5)
auditd.conf - audit daemon configuration file
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
approximately 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, and single. 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. Except for rotate,
it will perform this action just one time. The previously
available halt option, which would cause the audit daemon
to shut down the computer system, has been deprecated and
should no longer be used. It was determined that halting
the system at this stage could lead to unintended
consequences and is considered a bad action if selected.
Disk space notifications follow a three-stage progression.
The space_left_action is the low water mark and serves as
the first warning that disk space is running low. Halting
at this stage is not recommended, as it prevents
administrators from taking corrective action. The next
stage, admin_space_left_action, indicates an emergency
level where immediate action is required to free up disk
space. Administrators should configure critical responses
for this level. Finally, the disk_full_action occurs when
the disk is completely full. At this stage, the system may
have already halted, and preemptive measures configured in
earlier stages will determine the system’s behavior.
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 rotate, 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
privileged 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
2000.
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.
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.
/etc/audit/auditd.conf
Audit daemon configuration file
auditd(8), audisp-remote.conf(5), auditd-plugins(5).
Steve Grubb
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
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-01-31.) 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)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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