XYMON(7)

NAME
Xymon - introduction to Xymon

OVERVIEW
Xymon is a tool for monitoring the health of your networked servers and the applications running on them. It provides a simple, intuitive way of checking the health of your systems from a webbrowser, and can also alert you to any problems that arise through alarms sent as e-mail, SMS messages, via a pager or by other means. Xymon is Open Source software, licensed under the GNU GPL. This means that you are free to use Xymon as much as you like, and you are free to re-distribute it and change it to suit your specific needs. However, if you change it then you must make your changes available to others on the same terms that you received Xymon originally. See the file COPYING in the Xymon source-archive for details. Xymon was called "Hobbit" until November 2008, when it was renamed to Xymon. This was done because the name "Hobbit" is trademarked. The current release of Xymon is an interim version without all of the changes needed for a full renaming, so there are still quite a few references to the old "hobbit" name. Xymon initially began life as an enhancement to Big Brother called "bbgen". Over a period of 5 years, Xymon has evolved from a small add-on to a full-fledged monitoring system with capabilities far exceeding what was in the original Big Brother package. Xymon does still maintain some compatibility with Big Brother, so it is possible to migrate from Big Brother to Xymon without too much trouble. Migrating to Xymon will give you a significant performance boost, and provide you with much more advanced monitoring. The Xymon tools are designed for installations that need to monitor a large number of hosts, with very little overhead on the monitoring server. Monitoring of thousands of hosts with a single Xymon server is possible - it was developed to handle just this task.

FEATURES
These are some of the core features in Xymon:

Monitoring of hosts and networks
    Xymon collects information about your systems in two ways: From querying network services (Web, LDAP, DNS, Mail etc.), or from scripts that run either on the Xymon server or on the systems you monitor. The Xymon package includes a Xymon client which you can install on the servers you monitor; it collects data about the CPU-load, disk- and memory-utilisation, logfiles, network ports in use, file- and directory-information and more. All of the information is stored inside Xymon, and you can define conditions that result in alerts, e.g. if a network service stops responding, or a disk fills up.

Centralized configuration
    All configuration of Xymon is done on the Xymon server. Even when monitoring hundreds or thousands of hosts, you can control their configuration centrally on the Xymon server - so there is no need for you to login to a system just to change e.g. which processes are monitored.

Works on all major platforms
    The Xymon server works on all Unix-like systems, including Linux, Solaris, FreeBSD, AIX, HP-UX and others. The Xymon client supports all major Unix platforms, and there are other Open Source projects - e.g. BBWin, see http://bbwin.sourceforge.net/ - providing support for Microsoft Windows based systems.

A simple, intuitive web-based front-end
    "Green is good, red is bad". Using the Xymon webpages is as simple as that. The hosts you monitor can be grouped together in a way that makes sense in your organisation and presented in a tree-structure. The webpages use many techniques to convey information about the monitored systems, e.g. different icons can be used for recently changed statuses; links to subpages can be listed in multiple columns; different icons can be used for dialup-tests or reverse-tests; selected columns can be dropped or unconditionally included on the webpages to eliminate unwanted information, or always include certain information; user-friendly names can be shown for hosts regardless of their true hostname. You can also have automatic links to on-line documentation, so information about your critical systems is just a click away.

Integrated trend analysis, historical data and SLA reporting
    Xymon stores trend- and availability-information about everything it monitors. So if you need to look at how your systems behave over time, Xymon has all of the information you need: Whether is is response times of your webpages during peak hours, the CPU utilisation over the past 4 weeks, or what the availability of a site was compared to the SLA - it's all there inside Xymon. All measurements are tracked and made available in time-based graphs. When you need to drill down into events that have occurred, Xymon provides a powerful tool for viewing the event history for each statuslog, with overviews of when problems have occurred during the past and easy-to-use zoom-in on the event. For SLA reporting, You can configure planned downtime, agreed service availability level, service availability time and have Xymon generate availability reports directly showing the actual availability measured against the agreed SLA. Such reports of service availability can be generated on-the-fly, or pre-generated e.g. for monthly reporting.

Role-based views
    You can have multiple different views of the same hosts for different parts of the organisation, e.g. one view for the hardware group, and another view for the webmasters - all of them fed by the same test tools. If you have a dedicated Network Operations Centre, you can configure precisely which alerts will appear on their monitors - e.g. a simple anomaly in the system logfile need not trigger a call to 3rd-level support at 2 AM, but if the on-line shop goes down you do want someone to respond immediately. So you put the webcheck for the on-line shop on the NOC monitor page, and leave out the log-file check.

Also for the techies
    The Xymon user-interface is simple, but engineers will also find lots of relevant information. E.g. the data that clients report to Xymon contain the raw output from a number of system commands. That information is available directly in Xymon, so an administrator no longer needs to login to a server to get an overview of how it is behaving - the very commands they would normally run have alredy been performed, and the results are on-line in Xymon.

Easy to adapt to your needs
    Xymon includes a lot of tests in the core package, but there will always be something specific to your setup that you would like to watch. Xymon allows you to write test scripts in your favourite scripting language and have the results show up as regular status columns in Xymon. You can trigger alerts from these, and even track trends in graphs just by a simple configuration setting.

Real network service tests
    The network test tool knows how to test most commonly used protocols, including HTTP, SMTP (e-mail), DNS, LDAP (directory services), and many more. When checking websites, it is possible to not only check that the webserver is responding, but also that the response looks correct by matching the response against a pre-defined pattern or a checksum. So you can test that a network service is really working and supplying the data you expect - not just that the service is running. Protocols that use SSL encryption such as https-websites are fully supported, and while checking such services the network tester will automatically run a check of the validity of the SSL server certificate, and warn about certificates that are about to expire.

Highly configurable alerts
    You want to know when something breaks. But you don't want to get flooded with alerts all the time. Xymon lets you define several criteria for when to send out an alert, so you only get alerts when there is really something that needs your attention right away. While you are handling an incident, you can tell Xymon about it so it stops sending more alerts, and so that everyone else can check with Xymon and know that the problem is being taken care of.

Combined super-tests and test interdependencies
    If a single test is not enough, combination tests can be defined that combine the result of several tests to a single status-report. So if you need to monitor that at least 3 out of 5 servers are running at any time, Xymon can do that for you and generate the necessary availability report. Tests can also be configured to depend on each other, so that when a critical router goes down you will get alerts only for the router - and not from the 200 hosts behind the router.

SECURITY
All of the Xymon server tools run under an unprivileged user account. A single program - the hobbitping(1) network connectivity tester - must be installed setuid-root, but has been written so that it drops all root privileges immediately after performing the operation that requires root privileges. It is recommended that you setup a dedicated account for Xymon. Communications between the Xymon server and Xymon clients use the Big Brother TCP port 1984. If the Xymon server is located behind a firewall, it must allow for inbound connections to the Xymon server on tcp port 1984. Normally, Xymon clients - i.e. the servers you are monitoring - must be permitted to connect to the Xymon server on this port. However, if that is not possible due to firewall policies, then Xymon includes the hobbitfetch(8) and msgcache(8) tools to allows for a pull-style way of collecting data, where it is the Xymon server that initiates connections to the clients. The Xymon webpages are dynamically generated through CGI programs. Access to the Xymon webpages is controlled through your webserver access controls, e.g. you can require a login through some form of HTTP authentication.

DEMONSTRATION SITE
A site running this software can be seen at http://www.hswn.dk/hobbit/

PREREQUISITES AND INSTALLATION
You will need a Unix-like system (Linux, Solaris, HP-UX, AIX, FreeBSD, Mac OS X or similar) with a webserver installed. You will also need a C compiler and som additional libraries, but many systems come with the required development tools and libraries pre-installed. The required libraries are:

RRDtool This library is used to store and present trend-data. It is required.

libpcre This library is used for advanced pattern-matching of text strings in configuration files. This library is required.

OpenSSL This library is used for communication with SSL-enabled network services. Although optional, it is recommended that you install this for Xymon since many network tests do use SSL.

OpenLDAP This library is used for testing LDAP servers. Use of this is optional. For more detailed information about Xymon system requirements and how to install Xymon, refer to the online documentation "Installing Xymon" available from the Xymon webserver (via the "Help" menu), or from the "docs/install.html" file in the Xymon source archive.

SUPPORT and MAILING LISTS
hobbit@hswn.dk is an open mailing list for discussions about Xymon. If you would like to participate, send an e-mail to hobbit-subscribe@hswn.dk to join the list. An archive of the mailing list is available at http://www.hswn.dk/hobbiton/ If you just want to be notified of new releases of Xymon, please subscribe to the hobbit-announce mailing list. This is a moderated list, used only for announcing new Xymon releases. To be added to the list, send an e-mail to hobbit-announce-subscribe@hswn.dk.

XYMON SERVER TOOLS
These tools implement the core functionality of the Xymon server: hobbitd(8) is the core daemon that collects all reports about the status of your hosts. It uses a number of helper modules to implement certain tasks such as updating logfiles and sending out alerts: hobbitd_client, hobbitd_history, hobbitd_alert and hobbitd_rrd. There is also a hobbitd_filestore module for compatibility with Big Brother. hobbitd_channel(8) Implements the communication between the Xymon daemon and the other Xymon server modules. hobbitd_history(8) Stores historical data about the things that Xymon monitors. hobbitd_rrd(8) Stores trend data, which is used to generate graphs of the data monitored by Xymon. hobbitd_alert(8) handles alerts. When a status changes to a critical state, this module decides if an alert should be sent out, and to whom. hobbitd_client(8) handles data collected by the Xymon clients, analyzes the data and feeds back several status updates to Xymon to build the view of the client status. hobbitd_hostdata(8) stores historical client data when something breaks. E.g. when a webpage stops responding hobbitd_hostdata will save the latest client data, so that you can use this to view a snapshot of how the system state was just prior to it failing.

XYMON NETWORK TEST TOOLS
These tools are used on servers that execute tests of network services. hobbitping(1) performs network connectivity (ping) tests. bbtest-net(1) runs the network service tests. bbretest-net.sh(1) is an extension script for re-doing failed network tests with a higher frequency than the normal network tests. This allows Xymon to pick up the recovery of a network service as soon as it happens, resulting in less downtime being recorded.

XYMON TOOLS HANDLING THE WEB USER-INTERFACE
These tools take care of generating and updating the various Xymon web-pages. bbgen(1) takes care of updating the Xymon webpages. hobbitsvc.cgi(1) This CGI program generates an HTML view of a single status log. It is used to present the Xymon status-logs. hobbitgraph.cgi(1) This CGI program generates graphs of the trend-data collected by Xymon. hobbit-hostgraphs.cgi(1) When you want to combine multiple graphs into one, this CGI lets you combine graphs so you can e.g. compare the load on all of the nodes in your server farm. hobbit-nkview.cgi(1) Generates the Critical Systems view, based on the currently critical systems and the configuration of what systems and services you want to monitor when. bb-hist.cgi(1) This CGI program generates a webpage with the most recent history of a particular host+service combination. bb-eventlog.cgi(1) This CGI lets you view a log of events that have happened over a period of time, for a single host or test, or for multiple systems. bb-ack.cgi(1) This CGI program allows a user to acknowledge an alert he received from Xymon about a host that is in a critical state. Acknowledging an alert serves two purposes: First, it stops more alerts from being sent so the technicians are not bothered wit more alerts, and secondly it provides feedback to those looking at the Xymon webpages that the problem is being handled. hobbit-mailack(8) is a tool for processing acknowledgements sent via e-mail, e.g. as a response to an e-mail alert. hobbit-enadis.cgi(8) is a CGI program to disable or re-enable hosts or individual tests. When disabling a host or test, you stop alarms from being sent and also any outages do not affect the SLA calculations. So this tool is useful when systems are being brought down for maintenance. bb-findhost.cgi(1) is a CGI program that finds a given host in the Xymon webpages. As your Xymon installation grows, it can become difficult to remember exactly which page a host is on; this CGI script lets you find hosts easily. bb-rep.cgi(1) This CGI program triggers the generation of Xymon availability reports, using bbgen(1) as the reporting back-end engine. bb-replog.cgi(1) This CGI program generates the detailed availability report for a particular host+service combination. bb-snapshot.cgi(1) is a CGI program to build the Xymon webpages in a "snapshot" mode, showing the look of the webpages at a particular point in time. It uses bbgen(1) as the back-end engine. hobbit-statusreport.cgi(1) is a CGI program reporting test results for a single status but for several hosts. It is used to e.g. see which SSL certificates are about to expire, across all of the Xymon webpages. bb-csvinfo.cgi(1) is a CGI program to present information about a host. The information is pulled from a CSV (Comma Separated Values) file, which is easily exported from any spreadsheet or database program.

CLIENT-SIDE TOOLS
logfetch(1) is a utility used by the Xymon Unix client to collect information from logfiles on the client. It can also monitor various other file-related data, e.g. file metadata or directory sizes. clientupdate(1) Is used on Xymon clients, to automatically update the client software with new versions. Through this tool, updates of the client software can happen without an administrator having to logon to the server. msgcache(8) This tool acts as a mini Xymon server to the client. It stores client data internally, so that the hobbitfetch(8) utility can pick it up later and send it to the Xymon server. It is typically used on hosts that cannot contact the Xymon server directly due to network- or firewall-restrictions.

XYMON COMMUNICATION TOOLS
These tools are used for communications between the Xymon server and the Xymon clients. If there are no firewalls then they are not needed, but it may be necessary due to network or firewall issues to make use of them. bbproxy(8) is a proxy-server that forwards Xymon messages between clients and the Xymon server. The clients must be able to talk to the proxy, and the proxy must be able to talk to the Xymon server. hobbitfetch(8) is used when the client is not able to make outbound connections to neither bbproxy nor the Xymon server (typically, for clients located in a DMZ network zone). Together with the msgcache(8) utility running on the client, the Xymon server can contact the clients and pick up their data.

OTHER TOOLS
hobbitlaunch(8) is a program scheduler for Xymon. It acts as a master program for running all of the Xymon tools on a system. On the Xymon server, it controls running all of the server tasks. On a Xymon client, it periodically launches the client to collect data and send them to the Xymon server. bb(1) is the tool used to communicate with the Xymon server. It is used to send status reports to the Xymon server, through the custom Xymon/BB protocol, or via HTTP. It can be used to query the state of tests on the central Xymon server and retrieve Xymon configuration files. The server-side script bbmessage.cgi(1) used to receive messages sent via HTTP is also included. bbcmd(1) is a wrapper for the other Xymon tools which sets up all of the environment variables used by Xymon tools. bbhostgrep(1) is a utility for use by Xymon extension scripts. It allows an extension script to easily pick out the hosts that are relevant to a script, so it need not parse a huge bb-hosts file with lots of unwanted test-specifications. bbhostshow(1) is a utility to dump the full bb-hosts(5) file following any "include" statements. bbdigest(1) is a utility to compute message digest values for use in content checks that use digests. bbcombotest(1) is an extension script for the Xymon server, allowing you to build complicated tests from simpler Xymon test results. E.g. you can define a test that uses the results from testing your webserver, database server and router to have a single test showing the availability of your enterprise web application. trimhistory(8) is a tool to trim the Xymon history logs. It will remove all log entries and optionally also the individual status-logs for events that happened before a given time.

VERSIONS
Version 1 of bbgen was relased in November 2002, and optimized the webpage generation on Big Brother servers. Version 2 of bbgen was released in April 2003, and added a tool for performing network tests. Version 3 of bbgen was released in September 2004, and eliminated the use of several external libraries for network tests, resulting in a significant performance improvement. With version 4.0 released on March 30 2005, the project was de-coupled from Big Brother, and the name changed to Xymon. This version was the first full implementation of the Xymon server, but it still used the data collected by Big Brother clients for monitoring host metrics. Version 4.1 was released in July 2005 included a simple Xymon client for Unix. Logfile monitoring was not implemented. Version 4.2 was released in July 2006, and includes a fully functional Xymon client for Unix.

COPYRIGHT
Xymon is
  Copyright (C) 2002-2006, Henrik Storner <henrik@storner.dk>
Parts of the Xymon sources are from public-domain or other freely available sources. These are the the Red-Black tree implementation, and the MD5-, SHA1- and RIPEMD160-implementations. Details of the license for these is in the README file included with the Xymon sources. All other files are released under the GNU General Public License version 2, with the additional exemption that compiling, linking, and/or using OpenSSL is allowed. See the file COPYING for details.

SEE ALSO
hobbitd(8), hobbitd_channel(8), hobbitd_history(8), hobbitd_rrd(8), hobbitd_alert(8), hobbitd_client(8), hobbitd_hostdata(8), hobbitping(1), bbtest-net(1), bbretest-net.sh(1), bbgen(1), hobbitsvc.cgi(1), hobbitgraph.cgi(1), hobbit-hostgraphs.cgi(1), hobbit-nkview.cgi(1), bb-hist.cgi(1), bb-eventlog.cgi(1), bb-ack.cgi(1), hobbit-mailack(8), hobbit-enadis.cgi(8), bb-findhost.cgi(1), bb-rep.cgi(1), bb-replog.cgi(1), bb-snapshot.cgi(1), hobbit-statusreport.cgi(1), bb-csvinfo.cgi(1), logfetch(1), clientupdate(1), msgcache(8), bbproxy(8), hobbitfetch(8), hobbitlaunch(8), bb(1), bbmessage.cgi(1), bbcmd(1), bbhostgrep(1), bbhostshow(1), bbdigest(1), bbcombotest(1), trimhistory(8), bb-hosts(5), hobbitlaunch.cfg(5), hobbitserver.cfg(5), hobbit-alerts.cfg(5), hobbit-clients.cfg(5), client-local.cfg(5)