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AUDITD.CONF:(5)		System Administration Utilities	       AUDITD.CONF:(5)

NAME
       auditd.conf - audit daemon configuration file

DESCRIPTION
       The file /etc/audit/auditd.conf contains configuration information spe‐
       cific to the audit daemon.  It should contain one configuration keyword
       per line, an equal sign, and then followed by appropriate configuration
       information.  The  keywords  recognized	are:   log_file,   log_format,
       log_group,  priority_boost,  flush,  freq,  num_logs  , disp_qos , dis‐
       patcher,	 name_format  ,	  name,	  max_log_file,	  max_log_file_action,
       space_left,   action_mail_acct,	 space_left_action,  admin_space_left,
       admin_space_left_action, disk_full_action, disk_error_action,  tcp_lis‐
       ten_port,      tcp_listen_queue,	    tcp_max_per_addr,	  use_libwrap,
       tcp_client_ports, tcp_client_max_idle, enable_krb5, krb5_principal, and
       krb5_key_file.  These keywords are described below.

       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.

       log_format
	      The log format describes how the information should be stored on
	      disk.  There  are	 2 options: raw and nolog.  If set to RAW, the
	      audit records will be stored in a format exactly as  the	kernel
	      sends it. If this option is set to NOLOG then all audit informa‐
	      tion is discarded instead of writing to disk. This mode does not
	      affect data sent to the audit event dispatcher.

       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, 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
	      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.

       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.

       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 99 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 rota‐
	      tion 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.

       disp_qos
	      This  option controls whether you want blocking/lossless or non-
	      blocking/lossy communication between the audit  daemon  and  the
	      dispatcher.  There is a 128k buffer between the audit daemon and
	      dispatcher. This is good enogh for most uses. If lossy  is  cho‐
	      sen,  incoming events going to the dispatcher are discarded when
	      this queue is  full.  (Events  are  still	 written  to  disk  if
	      log_format  is not nolog.) Otherwise the auditd daemon will wait
	      for the queue to have an empty spot before logging to disk.  The
	      risk  is	that  while  the  daemon is waiting for network IO, an
	      event is not being recorded to disk. Valid values are: lossy and
	      lossless. Lossy is the default value.

       dispatcher
	      The  dispatcher is a program that is started by the audit daemon
	      when it starts up. It will pass a copy of all  audit  events  to
	      that  application's  stdin.  Make sure you trust the application
	      that you add to this line since it runs with root privileges.

       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 recom‐
	      mended  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  overwrit‐
	      ten.

       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 config‐
	      ured on your machine and network.	 Also,	this  option  requires
	      that /usr/lib/sendmail exists on the machine.

       space_left
	      This is a numeric value in megabytes that tells the audit daemon
	      when to perform a configurable  action  because  the  system  is
	      starting to run low on disk space.

       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, email, exec, suspend,
	      single, and halt.	 If set to ignore, the audit daemon does noth‐
	      ing.   syslog  means  that  it  will  issue a warning to syslog.
	      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  can‐
	      not 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.  The  halt	option
	      will cause the audit daemon to shutdown the computer system.

       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 run‐
	      ning  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.

       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, 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.  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 parame‐
	      ters 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.

       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,	 exec,
	      suspend,	single,	 and halt.  If set to ignore, the audit daemon
	      will issue a syslog message but no other action is taken.	  Sys‐
	      log  means  that it will issue a warning 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.

       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  exe‐
	      cute the script. You cannot pass parameters to the script.  Sus‐
	      pend 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	speci‐
	      fied,  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.

       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.

       tcp_max_per_addr
	      This is a numeric value which indicates how many concurrent con‐
	      nections	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 sepa‐
	      rated  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 priviledged 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.

       enable_krb5
	      If set to "yes", Kerberos 5 will be used for authentication  and
	      encryption.  The default is "no".

       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

NOTES
       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 par‐
       tition. 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 depend‐
       ing 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 recre‐
       ate a connection with the same host addresses and ports until the  con‐
       nection closure TIME_WAIT state times out.

FILES
       /etc/audit/auditd.conf
	      Audit daemon configuration file

SEE ALSO
       auditd(8), audisp-remote.conf(5).

AUTHOR
       Steve Grubb

Red Hat				   Dec 2008		       AUDITD.CONF:(5)
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