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Man Pages


Manual Reference Pages  -  RMONITOR (1)

NAME

rmonitor - remote system monitoring utility

CONTENTS

Synopsis
Description
Options
Display
Example
Files
See Also
History
Bugs
Author

SYNOPSIS

rmonitor [-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 periodically 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 preferred system only, on any system joining the multicast group or on any system receiving the broadcast packets. In any case, the server just collects 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 immediately 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 monitored. 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 section). 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 sufficient 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 registrate themselves in the multicast group, and multicast servers will also monitor unicast or broadcast clients. Specification of this flag when invoking servers is meaningful 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 corresponding 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 highlighting on the screen (see -r, too). The default value is 2.5 which allows a single packet loss between each two successful screen updates. Values less than or equal to 1.0 will be not accepted here.

DISPLAY

rmonitor 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 resolution 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 monitored, 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 unexpected 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
.Fx 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 number 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 ALSO

systat(1), top(1), uptime(1), sysctl(8)

HISTORY

rmonitor has been developed for
.Fx 4.2-STABLE. It is not part of the base system.

BUGS

rmonitor 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
.Fx prior to 4.2-RELEASE.

AUTHOR


.An Konrad Heuer Aq kheuer@gwdu60.gwdg.de
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