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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 ei- ther a device or local file. 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. auditd 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 ap- proaches 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 ex- ample, 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 ac- cepts a connection 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 au- dit 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 system) handles the request. When the master daemon is terminated, it terminates all of its child daemons. Reads a list of directories into which auditd may switch its audit log file when an overflow condition is reached. The list is main- tained 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 gen- eration number. These generation numbers range from 000 to 999. (Generation numbers may be overridden with an explicit genera- tion number specification on the pathname for the -l option, for example auditlog.345). The -x option causes a change in auditlog to the next auditlog in the generation number sequence. (If the current log was auditlog.345, then -x would change the log to auditlog.346). Whenever an auditlog is closed, it is also com- pressed (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 dae- mon. 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 dae- mons. Instructs the client audit daemon to not require acknowledgement from the server (machine collecting audit data) for the reciept of au- dit 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/au- ditd_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 co- operating 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. In- put 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 invoca- tion 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 dae- mon also turns on auditing for the system (audcntl(2)). When the dae- mon 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 es- tablish a communications path between the client and the server dae- mons, 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 trans- fer audit data to the server, a child audit daemon dedicated to commu- nicating 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 ac- knowledgment was not used on earlier systems. FILES RELATED INFORMATION Commands: audit_setup(8) Functions: audcntl(2) Files: audit(7) delim off auditd(8)