.TH IP\-MONITOR 8 "13 Dec 2012" "iproute2" "Linux"
.SH "NAME"
ip-monitor, rtmon \- state monitoring
.SH "SYNOPSIS"
.sp
.ad l
.in +8
.ti -8
.BR "ip " " [ ip-OPTIONS ] " "monitor" " [ " all " |"
.IR LISTofOBJECTS " ] [ file " FILENAME " ]
.sp

.SH DESCRIPTION
The
.B ip
utility can monitor the state of devices, addresses
and routes continuously.  This option has a slightly different format.
Namely, the
.B monitor
command is the first in the command line and then the object list follows:

.BR "ip monitor" " [ " all " |"
.IR LISTofOBJECTS " ] [ file " FILENAME " ]

.I OBJECT-LIST
is the list of object types that we want to monitor.
It may contain
.BR link ", " address ", " route ", " mroute ", " prefix ", "
.BR neigh " and " netconf "."
If no
.B file
argument is given,
.B ip
opens RTNETLINK, listens on it and dumps state changes in the format
described in previous sections.

.P
If a
.I FILENAME
is given, it does not listen on RTNETLINK,
but opens the file containing RTNETLINK messages saved in binary format
and dumps them.  Such a history file can be generated with the
.B rtmon
utility.  This utility has a command line syntax similar to
.BR "ip monitor" .
Ideally,
.B rtmon
should be started before the first network configuration command
is issued. F.e. if you insert:
.sp
.in +8
rtmon file /var/log/rtmon.log
.in -8
.sp
in a startup script, you will be able to view the full history
later.

.P
Certainly, it is possible to start
.B rtmon
at any time.
It prepends the history with the state snapshot dumped at the moment
of starting.

.SH SEE ALSO
.br
.BR ip (8)

.SH AUTHOR
Original Manpage by Michail Litvak <mci@owl.openwall.com>