The audit_control File

An audit_control file on each machine is read by the audit daemon (see the audit_control(4) man page). The audit_control file is located in the /etc/security directory. A separate audit_control file is maintained on each machine because machines in the distributed system may be mounting their audit file systems from different locations or specifying them in a different order. For example, the primary audit file system for machineA might be the secondary audit file system for machineB.

You specify four kinds of information in four kinds of lines in the audit_control file:

• The audit flags line (flags:) contains the audit flags that define what classes of events are audited for all users on the machine. The audit flags specified here are referred to as the machine-wide audit flags or the machine-wide audit preselection mask. Audit flags are separated by commas, with no spaces.

• The nonattributable flags line (naflags:) contains the audit flags that define what classes of events are audited when an action cannot be attributed to a specific user. The flags are separated by commas, with no spaces.

• The audit threshold line (minfree:) defines the minimum free-space level for all audit file systems. See "What Makes a Directory Suitable". The minfree percentage must be greater than or equal to 0. The default is 20 percent.

• The directory definition lines (dir:) define which audit file systems and directories the machine will use to store its audit trail files. There may be one or more directory definition lines. The order of the dir: lines is significant, because auditd opens audit files in the directories in the order specified (see the audit(1M) man page). The first audit directory specified is the primary audit directory for the machine, the second is the secondary audit directory where the audit daemon puts audit trail files when the first one fills, and so forth.

The administrator creates an audit_control file during the configuration process on each machine.

After the audit_control file is created during system configuration, the administrator can edit it. After a change, the administrator runs audit -s to instruct the audit daemon to reread the audit_control file.

The audit -s command does not change the preselection mask for existing processes. Use autoconfig, setaudit (see the getaudit(2) man page), or auditon for existing processes.

Sample audit_control File

Following is a sample audit_control file for the machine dopey. dopey uses two audit file systems on the audit server blinken, and a third audit file system mounted from the second audit server winken, which is used only when the audit file systems on blinken fill up or become unavailable. The minfree value of 20 percent specifies that the warning script (see the audit_warn(1M) man page) is run when the file systems are 80 percent filled and the audit data for the current machine will be stored in the next available audit directory, if any. The flags specify that all logins and administrative operations are to be audited (whether or not they succeed), and that failures of all types except failures to create a file system object are to be audited.

flags:lo,ad,-all,^-fc
naflags:lo,nt
minfree:20
dir:/etc/security/audit/blinken/files
dir:/etc/security/audit/blinken.1/files
#
# Audit filesystem used when blinken fills up
#
dir: /etc/security/audit/winken