Local configuration settings for xymon clients
The client-local.cfg file contains settings that are used by each Xymon client when it runs on a monitored host. It provides a convenient way of configuring clients from a central location without having to setup special configuration maintenance tools on all clients.
The client-local.cfg file is currently used to configure what logfiles the client should fetch data from, to be used as the basis for the "msgs" status column; and to configure which files and directories are being monitored in the "files" status column.
Note that there is a dependency between the client-local.cfg file and the analysis.cfg(5) file. When monitoring e.g. a logfile, you must first enter it into the client-local.cfg file, to trigger the Xymon client into reporting any data about the logfile. Next, you must configure analysis.cfg so the Xymon server knows what to look for in the file data sent by the client. So: client-local.cfg defines what raw data is collected by the client, and analysis.cfg defines how to analyze them.
The client-local.cfg file resides on the Xymon server.
When clients connect to the Xymon server to send in their client data, they will receive part of this file back from the Xymon server. The configuration received by the client is then used the next time the client runs.
This method of propagating the configuration means that there is a delay of up to two poll cycles (i.e. 5-10 minutes) from a configuration change is entered into the client-local.cfg file, and until you see the result in the status messages reported by the client.
By default, xymond will look for a matching entry by matching the client hostname, classname or operating system name against the section expressions. Hostname matches are used first, then classname matches, then OS matches. The first match found is the one that is returned to the client.
If xymond is started with the "--merge-clientlocal" option, then xymond will instead merge all of the matching sections into one, and return all of this data to the client. So you can have host-specific entries, and then supplement them with class- or os-generic entries. Note that the merging does not remove entries, so if you have e.g. a "log" entry defined in both a hostname- and an osname-matching section, then both entries will be sent back to the client.
The file is divided into sections, delimited by "[name]" lines. A section name can be either an operating system identifier - linux, solaris, hp-ux, aix, freebsd, openbsd, netbsd, darwin - or a hostname. When deciding which section to send to a client, Xymon will first look for a section named after the hostname of the client; if such a section does not exist, it will look for a section named by the operating system of the client. So you can configure special configurations for individual hosts, and have a default configuration for all other hosts of a certain type.
It will often be practical to use regular expressions for hostnames. To do this you must use
where <expression> is a Perl-compatible regular expression. The same kind of matching can be done on operating system or host class, using
Apart from the section delimiter, the file format is free-form, or rather it is defined by the tools that make use of the configuration.
A logfile configuration entry looks like this:
The log:FILENAME:SIZE line defines the filename of the log, and the maximum amount of data (in bytes) to send to the Xymon server. FILENAME is usually an explicit full-path filename on the client. If it is enclosed in backticks, it is a command which the Xymon client runs and each line of output from this command is then used as a filename. This allows scripting which files to monitor, e.g. if you have logfiles that are named with some sort of timestamp.
The ignore PATTERN line (optional) defines lines in the logfile which are ignored entirely, i.e. they are stripped from the logfile data before sending it to the Xymon server. It is used to remove completely unwanted "noise" entries from the logdata processed by Xymon. "PATTERN" is a regular expression.
The trigger PATTERN line (optional) is used only when there is more data in the log than the maximum size set in the "log:FILENAME:SIZE" line. The "trigger" pattern is then used to find particularly interesting lines in the logfile - these will always be sent to the Xymon server. After picking out the "trigger" lines, any remaining space up to the maximum size is filled in with the most recent entries from the logfile. "PATTERN" is a regular expression.
A special type of log-handling is possible, where the number of lines matching a regular expressions are merely counted. This is linecount:FILENAME, followed by a number of lines of the form ID:PATTERN. E.g.
A file monitoring entry is used to watch the meta-data of a file: Owner, group, size, permissions, checksum etc. It looks like this:
The file:FILENAME line defines the filename of the file to monitor. As with the "log:" entries, a filename enclosed in backticks means a command which will generate the filenames dynamically. The optional [:HASH] setting defines what type of hash to compute for the file: md5, sha1 or rmd160. By default, no hash is calculated.
NOTE: If you want to check multiple files using a wildcard, you must use a command to generate the filenames. Putting wildcards directly into the file: entry will not work.
A directory monitoring entry is used to watch the size of a directory and any sub-directories. It looks like this:
The dir:DIRECTORYNAME line defines the filename of the file to monitor. As with the "log:" entries, a filename enclosed in backticks means a command which will generate the filenames dynamically. The Xymon client will run the du(1) command with the directoryname as parameter, and send the output back to the Xymon server.
NOTE: If you want to check multiple directories using a wildcard, you must use a command to generate the directory names. Putting wildcards directly into the dir: entry will not work. E.g. use something like
dir:`find /var/log -maxdepth 1 -type d`
The "du" command used can be configured through the DU environment variable. On some systems, by default du reports data in disk blocks instead of KB (e.g. Solaris). So you may want to configure the Xymon client to use a du command which reports data in KB, e.g. by setting
in the xymonclient.cfg file.
The ability of the Xymon client to calculate file hashes and monitor those can be used for file integrity validation on a small scale. However, there is a significant processing overhead in calculating these every time the Xymon client runs, so this should not be considered a replacement for host-based intrusion detection systems such as Tripwire or AIDE.
Use of the directory monitoring on directory structures with a large number of files and/or sub-directories can be quite ressource-intensive.