RMONITOR(1) Contributed Software Manual RMONITOR(1)NAMErmonitor — remote system monitoring utility
SYNOPSISrmonitor [-h]
rmonitor [-c] [-n address] [-p port] [-r seconds] [-t ttl]
rmonitor [-l file] [-n address] [-p port] [-q] [-r seconds]
[-w tolerance]
DESCRIPTION
The rmonitor utility is a network-based client-server application for
monitoring remote systems.
Each system to be monitored needs to run an rmonitor client which period‐
ically sends the gathered system information either to a preferred system
running the server, to a multicast group or to a broadcast address.
Depending on the destination address, the server can be run on the pre‐
ferred system only, on any system joining the multicast group or on any
system receiving the broadcast packets. In any case, the server just col‐
lects and displays all incoming information. Since udp is used there is
no need for a reliable connection between client and server.
rmonitor is believed not to be a threat to system security since it does
not need a privileged mode to run. If invoked by root, rmonitor immedi‐
ately discards any privilege and changes its real and effective user and
group ID to those of the user nobody. The clients do not receive any
data; there is no additional open server port on a host which is moni‐
tored. To be very cautious, the rmonitor server which indeed receives and
displays data may be run on a less critical system.
OPTIONS
Available options:
-c Invokes the rmonitor client. There is no special flag to
invoke the server since this is done by default.
-h Used in earlier versions of rmonitor to print some help on
standard output. Obsolete now, since this man page has
become available, and kept only for compatibility. Will
cause the newer versions of rmonitor to call man(1) with an
appropriate argument to show the man page.
-l file Log file name; the rmonitor server will log all incoming
system status information to the specified file. The log
file format is similar to screen output (see DISPLAY sec‐
tion). The only difference is that last refresh times are
not logged since they are meaningless in the log file, and
instead of these a column containing the current time is
inserted. Please note that path and file must have suffi‐
cient permissions for the user nobody if rmonitor has been
invoked by root.
-n address By default, an rmonitor client sends the gathered system
status information to the standard network broadcast
address. A different address, in decimal dotted notation,
either a host or a broadcast address, can be given here.
Alternatively, a multicast address like 225.10.1.1 can be
specified. In the latter case, the same address has to be
specified on both clients and servers. Servers will regis‐
trate themselves in the multicast group, and multicast
servers will also monitor unicast or broadcast clients.
Specification of this flag when invoking servers is mean‐
ingful only when using multicast.
-p port Number of port to use for transmitting data in numerical
notation; default value is 3661. Newer versions of rmonitor
allow full port reuse; thus multiple instances of the
server may be run on a single host.
-q Quiet mode; causes the server to suppress all standard and
screen output. May be useful in combination with -l when
logging in the background is required.
-r seconds Refresh time in seconds which should be kept uniform within
a coherent client-server group. The default refresh time is
30 seconds. The server needs to know about the refresh time
of the clients to calculate a tolerance (2.5 times refresh
time per default, see -w ) used for highlighting. Hosts
will be assumed not to send anymore if the time since the
last message arrived is out of this range, and the corre‐
sponding screen line will be displayed in an emphasized
mode.
-t ttl Time to live for multicast packets when using multicast,
defaults to a value of four. In general, the higher this
value, the farther the packets will travel.
-w tolerance Factor used to calculate the tolerance value used for high‐
lighting on the screen (see -r, too). The default value is
2.5 which allows a single packet loss between each two suc‐
cessful screen updates. Values less than or equal to 1.0
will be not accepted here.
DISPLAYrmonitor prints one line of status information for each host monitored.
The data shown are:
HOST Host name without domain information of the monitored system;
since this name is sent by the remote host, host name resolu‐
tion is not required on the system running the server. Host
names longer than seven characters will be truncated to seven
characters before they are displayed.
REFRESH Approximate time since last refresh; the more hosts are moni‐
tored, the more accurate will this information be. The values
in this column are recalculated and redisplayed each time a
packet from any of the clients arrives. Time format is:
-hh:mm:ss (hours, minutes and seconds).
UPTIME Time since last boot of the remote system. The format is:
+ddd+hh:mm (days, hours and minutes).
#U Number of users currently logged in.
SL Security level the kernel runs in. Although this information
is rather static, this column may help to detect an unex‐
pected low security level.
DB Number of dirty buffers the contents of which have not yet
been written to mass storage.
LOADAVG Load average over the last 1 and 5 minutes.
PROCESSES Total number of processes; and relative number of processes
compared to the maximal number of processes possible, given
in percent.
FILES Total number of open files; and relative number of open files
compared to the maximal number of open files possible, given
in percent. For clients running on FreeBSD systems prior to
4.2-RELEASE, only quotation marks will be shown here.
MEM(ABW) Memory utilization; number of megabytes in use for active and
wired pages and for the buffer cache. Additionally this num‐
ber is compared to the size of the real memory available and
memory utilization is also given in percent.
EXAMPLE
An rmonitor client is invoked which sends the gathered information to a
multicast group instead of using broadcast packets:
rmonitor-c -n 225.10.1.1
The server for collecting and displaying the data can now be started on
the same or any other host by joining the multicast group:
rmonitor-n 225.10.1.1
FILES
/usr/local/etc/rc.d/rmonitor.sh
SEE ALSOsystat(1), top(1), uptime(1), sysctl(8)HISTORYrmonitor has been developed for FreeBSD 4.2-STABLE. It is not part of the
base system.
BUGSrmonitor depends on a sufficient display size of at less 79 columns and
two rows more than number of hosts to monitor. There is no warning in
case of unsufficient display size.
rmonitor should gather, transmit and show more information.
The information displayed by rmonitor may be incomplete or partially be
incorrect for versions of FreeBSD prior to 4.2-RELEASE.
AUTHOR
Konrad Heuer ⟨kheuer@gwdu60.gwdg.de⟩
BSD July 20th, 2001 BSD
