This target can be used to identify when interfaces have been idle for a
certain period of time.  Timers are identified by labels and are created when
a rule is set with a new label.  The rules also take a timeout value (in
seconds) as an option.  If more than one rule uses the same timer label, the
timer will be restarted whenever any of the rules get a hit.  One entry for
each timer is created in sysfs.  This attribute contains the timer remaining
for the timer to expire.  The attributes are located under the xt_idletimer
class:
.PP
/sys/class/xt_idletimer/timers/<label>
.PP
When the timer expires, the target module sends a sysfs notification to the
userspace, which can then decide what to do (eg. disconnect to save power).
.TP
\fB\-\-timeout\fP \fIamount\fP
This is the time in seconds that will trigger the notification.
.TP
\fB\-\-label\fP \fIstring\fP
This is a unique identifier for the timer.  The maximum length for the
label string is 27 characters.
.TP
\fB\-\---send_nl_msg\fP
Send netlink messages in addition to sysfs notifications and show remaining
time.
