The rlm_radutmp module enables the logging to a utmp-like file.

Configuration

	#  Write a 'utmp' style file, of which users are currently
	#  logged in, and where they've logged in from.
	#
	#  This file is used mainly for Simultaneous-Use checking,
	#  and also 'radwho', to see who's currently logged in.
	#
	radutmp {
		#  Where the file is stored.  It's not a log file,
		#  so it doesn't need rotating.
		#
		filename = ${logdir}/radutmp

		#  The field in the packet to key on for the
		#  'user' name,  If you have other fields which you want
		#  to use to key on to control Simultaneous-Use,
		#  then you can use them here.
		#
		#  Note, however, that the size of the field in the
		#  'utmp' data structure is small, around 32
		#  characters, so that will limit the possible choices
		#  of keys.
		#
		#  You may want instead: %{Stripped-User-Name:-%{User-Name}}
		username = %{User-Name}


		#  Whether or not we want to treat "user" the same
		#  as "USER", or "User".  Some systems have problems
		#  with case sensitivity, so this should be set to
		#  'no' to enable the comparisons of the key attribute
		#  to be case insensitive.
		#
		case_sensitive = yes

		#  Accounting information may be lost, so the user MAY
		#  have logged off of the NAS, but we haven't noticed.
		#  If so, we can verify this information with the NAS,
		#
		#  If we want to believe the 'utmp' file, then this
		#  configuration entry can be set to 'no'.
		#
		check_with_nas = yes		

		# Set the file permissions, as the contents of this file
		# are usually private.
		perm = 0600

		callerid = "yes"
	}

sradutmp

	# "Safe" radutmp - does not contain caller ID, so it can be
	# world-readable, and radwho can work for normal users, without
	# exposing any information that isn't already exposed by who(1).
	#
	# This is another 'instance' of the radutmp module, but it is given
	# then name "sradutmp" to identify it later in the "accounting"
	# section.
	radutmp sradutmp {
		filename = ${logdir}/sradutmp
		perm = 0644
		callerid = "no"
	}