1AUDITD.CONF:(5) System Administration Utilities AUDITD.CONF:(5)
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6 auditd.conf - audit daemon configuration file
7
9 The file /etc/audit/auditd.conf contains configuration information spe‐
10 cific to the audit daemon. It should contain one configuration keyword
11 per line, an equal sign, and then followed by appropriate configuration
12 information. The keywords recognized are: log_file, log_format,
13 log_group, priority_boost, flush, freq, num_logs , disp_qos , dis‐
14 patcher, name_format , name, max_log_file, max_log_file_action,
15 space_left, action_mail_acct, space_left_action, admin_space_left,
16 admin_space_left_action, disk_full_action, disk_error_action, tcp_lis‐
17 ten_port, tcp_listen_queue, tcp_max_per_addr, use_libwrap,
18 tcp_client_ports, tcp_client_max_idle, enable_krb5, krb5_principal, and
19 krb5_key_file. These keywords are described below.
20 log_file
23 This keyword specifies the full path name to the log file where
24 audit records will be stored. It must be a regular file.
25 log_format
27 The log format describes how the information should be stored on
28 disk. There are 2 options: raw and nolog. If set to RAW, the
29 audit records will be stored in a format exactly as the kernel
30 sends it. If this option is set to NOLOG then all audit informa‐
31 tion is discarded instead of writing to disk. This mode does not
32 affect data sent to the audit event dispatcher.
33 log_group
35 This keyword specifies the group that is applied to the log
36 file's permissions. The default is root. The group name can be
37 either numeric or spelled out.
38 priority_boost
40 This is a non-negative number that tells the audit daemon how
41 much of a priority boost it should take. The default is 4. No
42 change is 0.
43 flush Valid values are none, incremental, data, and sync. If set to
45 none, no special effort is made to flush the audit records to
46 disk. If set to incremental, Then the freq parameter is used to
47 determine how often an explicit flush to disk is issued. The
48 data parameter tells the audit damon to keep the data portion of
49 the disk file sync'd at all times. The sync option tells the
50 audit daemon to keep both the data and meta-data fully sync'd
51 with every write to disk.
52 freq This is a non-negative number that tells the audit damon how
54 many records to write before issuing an explicit flush to disk
55 command. this value is only valid when the flush keyword is set
56 to incremental.
57 num_logs
59 This keyword specifies the number of log files to keep if rotate
60 is given as the max_log_file_action. If the number is < 2, logs
61 are not rotated. This number must be 99 or less. The default is
62 0 - which means no rotation. As you increase the number of log
63 files being rotated, you may need to adjust the kernel backlog
64 setting upwards since it takes more time to rotate the files.
65 This is typically done in /etc/audit/audit.rules. If log rota‐
66 tion is configured to occur, the daemon will check for excess
67 logs and remove them in effort to keep disk space available. The
68 excess log check is only done on startup and when a reconfigure
69 results in a space check.
70 disp_qos
72 This option controls whether you want blocking/lossless or non-
73 blocking/lossy communication between the audit daemon and the
74 dispatcher. There is a 128k buffer between the audit daemon and
75 dispatcher. This is good enogh for most uses. If lossy is cho‐
76 sen, incoming events going to the dispatcher are discarded when
77 this queue is full. (Events are still written to disk if
78 log_format is not nolog.) Otherwise the auditd daemon will wait
79 for the queue to have an empty spot before logging to disk. The
80 risk is that while the daemon is waiting for network IO, an
81 event is not being recorded to disk. Valid values are: lossy and
82 lossless. Lossy is the default value.
83 dispatcher
85 The dispatcher is a program that is started by the audit daemon
86 when it starts up. It will pass a copy of all audit events to
87 that application's stdin. Make sure you trust the application
88 that you add to this line since it runs with root privileges.
89 name_format
91 This option controls how computer node names are inserted into
92 the audit event stream. It has the following choices: none,
93 hostname, fqd, numeric, and user. None means that no computer
94 name is inserted into the audit event. hostname is the name
95 returned by the gethostname syscall. The fqd means that it takes
96 the hostname and resolves it with dns for a fully qualified
97 domain name of that machine. Numeric is similar to fqd except
98 it resolves the IP address of the machine. In order to use this
99 option, you might want to test that 'hostname -i' or 'domainname
100 -i' returns a numeric address. Also, this option is not recom‐
101 mended if dhcp is used because you could have different
102 addresses over time for the same machine. User is an admin
103 defined string from the name option. The default value is none.
104 name This is the admin defined string that identifies the machine if
106 user is given as the name_format option.
107 max_log_file
109 This keyword specifies the maximum file size in megabytes. When
110 this limit is reached, it will trigger a configurable action.
111 The value given must be numeric.
112 max_log_file_action
114 This parameter tells the system what action to take when the
115 system has detected that the max file size limit has been
116 reached. Valid values are ignore, syslog, suspend, rotate and
117 keep_logs. If set to ignore, the audit daemon does nothing.
118 syslog means that it will issue a warning to syslog. suspend
119 will cause the audit daemon to stop writing records to the disk.
120 The daemon will still be alive. The rotate option will cause the
121 audit daemon to rotate the logs. It should be noted that logs
122 with higher numbers are older than logs with lower numbers. This
123 is the same convention used by the logrotate utility. The
124 keep_logs option is similar to rotate except it does not use the
125 num_logs setting. This prevents audit logs from being overwrit‐
126 ten.
127 action_mail_acct
129 This option should contain a valid email address or alias. The
130 default address is root. If the email address is not local to
131 the machine, you must make sure you have email properly config‐
132 ured on your machine and network. Also, this option requires
133 that /usr/lib/sendmail exists on the machine.
134 space_left
136 This is a numeric value in megabytes that tells the audit daemon
137 when to perform a configurable action because the system is
138 starting to run low on disk space.
139 space_left_action
141 This parameter tells the system what action to take when the
142 system has detected that it is starting to get low on disk
143 space. Valid values are ignore, syslog, email, exec, suspend,
144 single, and halt. If set to ignore, the audit daemon does noth‐
145 ing. syslog means that it will issue a warning to syslog.
146 Email means that it will send a warning to the email account
147 specified in action_mail_acct as well as sending the message to
148 syslog. exec /path-to-script will execute the script. You can‐
149 not pass parameters to the script. suspend will cause the audit
150 daemon to stop writing records to the disk. The daemon will
151 still be alive. The single option will cause the audit daemon to
152 put the computer system in single user mode. halt option will
153 cause the audit daemon to shutdown the computer system.
154 admin_space_left
156 This is a numeric value in megabytes that tells the audit daemon
157 when to perform a configurable action because the system is run‐
158 ning low on disk space. This should be considered the last
159 chance to do something before running out of disk space. The
160 numeric value for this parameter should be lower than the number
161 for space_left.
162 admin_space_left_action
164 This parameter tells the system what action to take when the
165 system has detected that it is low on disk space. Valid values
166 are ignore, syslog, email, exec, suspend, single, and halt. If
167 set to ignore, the audit daemon does nothing. Syslog means that
168 it will issue a warning to syslog. Email means that it will
169 send a warning to the email account specified in
170 action_mail_acct as well as sending the message to syslog. exec
171 /path-to-script will execute the script. You cannot pass parame‐
172 ters to the script. Suspend will cause the audit daemon to stop
173 writing records to the disk. The daemon will still be alive. The
174 single option will cause the audit daemon to put the computer
175 system in single user mode. halt
176 disk_full_action
178 This parameter tells the system what action to take when the
179 system has detected that the partition to which log files are
180 written has become full. Valid values are ignore, syslog, exec,
181 suspend, single, and halt. If set to ignore, the audit daemon
182 will issue a syslog message but no other action is taken. Sys‐
183 log means that it will issue a warning to syslog. exec /path-
184 to-script will execute the script. You cannot pass parameters to
185 the script. Suspend will cause the audit daemon to stop writing
186 records to the disk. The daemon will still be alive. The single
187 option will cause the audit daemon to put the computer system in
188 single user mode. halt option will cause the audit daemon to
189 shutdown the computer system.
190 disk_error_action
192 This parameter tells the system what action to take whenever
193 there is an error detected when writing audit events to disk or
194 rotating logs. Valid values are ignore, syslog, exec, suspend,
195 single, and halt. If set to ignore, the audit daemon will issue
196 a syslog message but no other action is taken. Syslog means
197 that it will issue a warning to syslog. exec /path-to-script
198 will execute the script. You cannot pass parameters to the
199 script. Suspend will cause the audit daemon to stop writing
200 records to the disk. The daemon will still be alive. The single
201 option will cause the audit daemon to put the computer system in
202 single user mode. halt option will cause the audit daemon to
203 shutdown the computer system.
204 tcp_listen_port
206 This is a numeric value in the range 1..65535 which, if speci‐
207 fied, causes auditd to listen on the corresponding TCP port for
208 audit records from remote systems. The audit daemon may be
209 linked with tcp_wrappers. You may want to control access with an
210 entry in the hosts.allow and deny files.
211 tcp_listen_queue
213 This is a numeric value which indicates how many pending
214 (requested but unaccepted) connections are allowed. The default
215 is 5. Setting this too small may cause connections to be
216 rejected if too many hosts start up at exactly the same time,
217 such as after a power failure.
218 tcp_max_per_addr
220 This is a numeric value which indicates how many concurrent con‐
221 nections from one IP address is allowed. The default is 1 and
222 the maximum is 16. Setting this too large may allow for a Denial
223 of Service attack on the logging server. The default should be
224 adequate in most cases unless a custom written recovery script
225 runs to forward unsent events. In this case you would increase
226 the number only large enough to let it in too.
227 use_libwrap
229 This setting determines whether or not to use tcp_wrappers to
230 discern connection attempts that are from allowed machines.
231 Legal values are either yes, or no The default value is yes.
232 tcp_client_ports
234 This parameter may be a single numeric value or two values sepa‐
235 rated by a dash (no spaces allowed). It indicates which client
236 ports are allowed for incoming connections. If not specified,
237 any port is allowed. Allowed values are 1..65535. For example,
238 to require the client use a priviledged port, specify 1-1023 for
239 this parameter. You will also need to set the local_port option
240 in the audisp-remote.conf file. Making sure that clients send
241 from a privileged port is a security feature to prevent log
242 injection attacks by untrusted users.
243 tcp_client_max_idle
245 This parameter indicates the number of seconds that a client may
246 be idle (i.e. no data from them at all) before auditd complains.
247 This is used to close inactive connections if the client machine
248 has a problem where it cannot shutdown the connection cleanly.
249 Note that this is a global setting, and must be higher than any
250 individual client heartbeat_timeout setting, preferably by a
251 factor of two. The default is zero, which disables this check.
252 enable_krb5
254 If set to "yes", Kerberos 5 will be used for authentication and
255 encryption. The default is "no".
256 krb5_principal
258 This is the principal for this server. The default is "auditd".
259 Given this default, the server will look for a key named like
260 auditd/hostname@EXAMPLE.COM stored in /etc/audit/audit.key to
261 authenticate itself, where hostname is the canonical name for
262 the server's host, as returned by a DNS lookup of its IP
263 address.
264 krb5_key_file
266 Location of the key for this client's principal. Note that the
267 key file must be owned by root and mode 0400. The default is
268 /etc/audit/audit.key
269
272 In a CAPP environment, the audit trail is considered so important that
273 access to system resources must be denied if an audit trail cannot be
274 created. In this environment, it would be suggested that /var/log/audit
275 be on its own partition. This is to ensure that space detection is
276 accurate and that no other process comes along and consumes part of it.
277 The flush parameter should be set to sync or data.
279 Max_log_file and num_logs need to be adjusted so that you get complete
281 use of your partition. It should be noted that the more files that have
282 to be rotated, the longer it takes to get back to receiving audit
283 events. Max_log_file_action should be set to keep_logs.
284 Space_left should be set to a number that gives the admin enough time
286 to react to any alert message and perform some maintenance to free up
287 disk space. This would typically involve running the aureport -t report
288 and moving the oldest logs to an archive area. The value of space_left
289 is site dependant since the rate at which events are generated varies
290 with each deployment. The space_left_action is recommended to be set to
291 email. If you need something like an snmp trap, you can use the exec
292 option to send one.
293 Admin_space_left should be set to the amount of disk space on the audit
295 partition needed for admin actions to be recorded.
296 Admin_space_left_action would be set to single so that use of the
297 machine is restricted to just the console.
298 The disk_full_action is triggered when no more room exists on the par‐
300 tition. All access should be terminated since no more audit capability
301 exists. This can be set to either single or halt.
302 The disk_error_action should be set to syslog, single, or halt depend‐
304 ing on your local policies regarding handling of hardware malfunctions.
305 Specifying a single allowed client port may make it difficult for the
307 client to restart their audit subsystem, as it will be unable to recre‐
308 ate a connection with the same host addresses and ports until the con‐
309 nection closure TIME_WAIT state times out.
310
313 /etc/audit/auditd.conf
314 Audit daemon configuration file
315
318 auditd(8), audisp-remote.conf(5).
319
322 Steve Grubb
323Red Hat Dec 2008 AUDITD.CONF:(5)