auditd(8) System Manager's Manual auditd(8)
NAME
auditd - Audit daemon
SYNOPSIS
/usr/sbin/auditd [ options ... ]
FLAGS
Audit Data and Messages
Sets the pathname to which the audit daemon will post any warning or informational messages (such as "audit log change"). This may be
either syslog, a device or local file. By default, messages are logged by syslogd to the daemon.log. Outputs a brief help menu. Causes
the audit daemon to transfer its audit data to the audit daemon executing on the remote host hostname. If the remote site stops receiving,
the local daemon will store its data locally as specified with the -o and -r options to auditd. Causes the audit daemon to output its
audit data to the local file pathname. Queries the audit daemon for the current location of the audit data.
Audit in a Cluster
Executes auditd across each active memmber of a cluster.
The following auditd options are not supported when the -cluster option is used: -l hostname: (-l pathname is supported) -p, -s, -t, -u, -z
The auditd options that are supported under -cluster are as follows: -h, -q, -d, -r, -w, -x, -n, -f, -o
-c Each cluster member may write to the same console file
or its own syslogd file.
-l pathname
The default audit log pathname is /var/audit/auditlog.hostname.nnn.
In a cluster, hostname becomes membername.
If the log file name does not already include it, each cluster
member appends dot (.) followed by the hostname. This prevents
file name collisions in clusters. Domain names are removed from
the host names.
-k Note that a local auditd must be running in order
to kill other members of a cluster.
Audit Control
Causes the audit subsystem to dump its currently buffered audit data (from the kernel and the daemon) out to the configured host or log
file. The audit daemon normally dumps its buffer only when it approaches capacity.
If a frequency (freq) is specified, the audit daemon dumps its data at the specified frequency. The freq is specified as n[wdhms]
for weeks, days, hours, minutes, and seconds. For example, to dump the audit daemon data every 36 hours use the -d 1d12h option.
Specifying 0s (zero seconds) disables the previously specified frequency. Terminates the audit daemon (terminating the local daemon
turns audit off). Specifies the ID of the audit daemon to receive the current options. When the local audit daemon accepts a con-
nection to receive data from a remote audit daemon, a dedicated child audit daemon is spawned off from the local audit daemon to
service that connection. With this scenario, multiple audit daemons may exist on a single system. Specifying the ID of the auditd
allows for communication with one of the child audit daemons. The ID for each daemon can be found by entering the following at the
command line:
# /usr/sbin/auditd -w
The previous command line displays the current options. No IDs are displayed unless at least one child audit daemon exists. If the
-p option is not specified when running with more than one audit daemon, the master daemon (accepting audit data for the local sys-
tem) handles the request. When the master daemon is terminated, it terminates all of its child daemons. Reads a list of directo-
ries into which auditd may switch its audit log file when an overflow condition is reached. The list is maintained in
/etc/sec/auditd_loc. The maximum size of the list (/etc/sec/auditd_loc) is 8 Kbytes. The -r option is used when the overflow
action is set to changeloc (auditd -o changeloc). Shows the current status of the audit daemons options. Auditlog pathnames are
always appended with a suffix consisting of a generation number. These generation numbers range from 000 to 999. (Generation num-
bers may be overridden with an explicit generation number specification on the pathname for the -l option, for example audit-
log.hostname.345). The -x option causes a change in auditlog to the next auditlog in the generation number sequence. (If the cur-
rent log was auditlog.hostname.345, then -x would change the log to auditlog.hostname.346). Whenever an auditlog is closed, it is
also compressed (by /usr/ucb/compress). This option is used to start the audit daemon server on a system not configured for audit.
The -z option removes any AF_UNIX sockets left by previous daemons. This situation can occur when the system shuts down abnormally.
If no AF_UNIX socket is present, the next invocation of will start the daemon. If an AF_UNIX socket is present, the next invocation
of spawns a client process which communicates with the system audit daemon. This -z option should be used only when no audit daemon
is present on the system.
Network
Sets the size of the audit daemons buffer for the audit data (minimum is 4). Toggles the network server switch. If on, allows the audit
daemon to accept audit data from other audit daemons whose host names are specified in the /etc/sec/auditd_clients file. Sets the timeout
value used in establishing initial connections with remote audit daemons. Instructs the client audit daemon to not require acknowledgement
from the server (machine collecting audit data) for the reciept of audit data sent over the network. The -u option is used for compatibil-
ity with servers that are running versions of DIGITAL UNIX prior to Version 4.0D.
Overflow Control
Sets the minimum percent free space on the current partition before an overflow condition is triggered. Sets the action that auditd takes
on an overflow condition. The following actions are available for the -o option: Change to the next directory or host machine (auditd on
the host machine determines the path) as specified in the /etc/sec/auditd_loc file. Suspend auditing.
Overwrite the current audit log file. This action causes the loss of previously logged audit data. Terminates the audit daemon. Immedi-
ately halts the system by doing a reboot.
DESCRIPTION
The audit daemon, auditd, operates as a server, monitoring /dev/audit for local audit data, monitoring a known port for data from remote
cooperating audit daemons, and monitoring an AF_UNIX socket for input from the system administrator.
Local audit data is shared with the /dev/audit device, and eventually is sent to the auditlog when the buffer nears capacity or the daemon
receives an explicit instruction from the administrator to flush its buffer.
Local administrative data is read via the socket /dev/.audit/audS. Input from the system administrator allows for changing of the daemon's
configurable options. The administrator communicates with the audit daemon by executing auditd with the desired options. The first invo-
cation of auditd spawns the daemon; subsequent invocations detect that an audit daemon already exists and will communicate with it, passing
along directions for the selected options. The first invocation of the daemon also turns on auditing for the system (audcntl(2)). When
the daemon is terminated, by the -k option or the SIGTERM signal, auditing is turned off. It is important not to have system auditing
turned on when there is no audit daemon running on the system (processes being audited will sleep on resources under control of the audit
system).
Remote audit data is first detected when a client (remote) audit daemon attempts to communicate with the server (local) audit daemon. To
establish a communications path between the client and the server daemons, the client's host name is first checked against a list of hosts
allowed to transmit data to the server. This list is maintained on the server in /etc/sec/auditd_clients. If the client is allowed to
transfer audit data to the server, a child audit daemon dedicated to communicating with that client is spawned.
Any data transferred from the client to the server is acknowledged (ack'ed) by the server. If the data transfer fails, the client follows
its "overflow" option. For communication with servers on systems prior to Version 4.0D, the client must use the -u option, because data
acknowledgment was not used on earlier systems.
The audit daemon can be terminated by using either of the following commands: # rcmgr -c delete AIDITMASK_FLAG # rcmgr -c delete AID-
ITD_FLAG or # auditmask [-cluster] -n # auditd [-cluster] -dk
Running auditd in a Cluster
The auditd daemon runs on each member of a cluster and logs to a common /var/audit directory by default. Audit log files now include the
host name to prevent file name overlap. The -cluster option can be used to modify each active member of a cluster. Restrictions are noted
in the -cluster flag's description. When reading a file with the -cluster opton, make sure the file is visible to each cluster member.
FILES
RELATED INFORMATION
Commands: auditconfig(8)
Functions: audcntl(2)
Files: audit(7) delim off
auditd(8)
