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Nagios Data Output Utilities

TL;DR? You can jump straight to compiling, initializing, installing the broker module, and installing the daemon.

The NDOUtils (Nagios Data Output Utilities) addon allows you to move status and event information from Nagios to a MySQL Database for later retrieval and processing.

This addon consists of several parts. Here are the most interesting ones...

  1. The NDOMOD event broker module. This module is intended to be loaded by the Nagios process at runtime. Its only role is to dump all events and data from Nagios to a TCP socket or a regular file or Unix domain socket on the local filesystem somewhere. If you want realtime transfer of data to MySQL, dump the data to a TCP or Unix domain socket. If you want delayed transfer of data into MySQL (i.e. you need to transfer the data to another host first), dump the data to a regular file.

  2. The NDO2DB daemon. This standalone daemon reads input (that was produced by the NDOMOD broker module) from a TCP or Unix domain socket, parses that data, and then dumps it into one or more MySQL databases. The daemon is capable of handling multiple client connections simultaneously, so you can have multiple instances of the NDOMOD module writing to the same TCP or Unix domain socket at the same time.

  3. The FILE2SOCK utility. This simple utility reads data from a standard file and dumps it to either a TCP or a Unix domain socket. This is useful if you are having the NDOMOD module write to a standard file that you later want to send to the NDO2DB daemon. If the module and the daemon are running on different machines, you can periodically use SSH to transfer the file from the monitoring machine to the machine running the NDO2DB daemon, and then use the FILE2SOCK utility to send the contents of that file to the TCP socket or Unix domain socket that the NDO2DB daemon is reading.

  4. The LOG2NDO utility. This utility is used for importing historical log archives from NetSaint and Nagios and sending them to the NDO2DB daemon. It takes a single log file as its input and can output data to either a TCP socket, a Unix domain socket or standard output.


Use the following commands to compile the NDO broker module, NDO2DB daemon, and additional utilities:

make all

If the configure script is unable to locate your MySQL development libraries, you may need to help it out by using the --with-mysql-lib option. Here's an example:

./configure --with-mysql-lib=/usr/lib/mysql

Initializing the Database

Before you start using NDOUtils, you should create the database where you will be storing all Nagios related information.

Note: Only MySQL Databases are supported!

  1. Create a database for storing the data (e.g. nagios)

  2. Create a username/password that has at least the following privileges for the database:

  3. Run the DB installation script in the db/ subdirectory of the NDO distribution to create the necessary tables in the database.

    cd db
  4. Make sure the database name, prefix, and username/password you just created and setup match the variable specified in the NDO2DB config file (see below).

Installing the Broker Module

There are three different versions of the NDOMOD module that get compiled, so make sure you use the module that matches the version of Nagios you are running, and adjust the directions given below to fit the name of the module version you're using.

  • ndomod-2x.o = NDOMOD module for Nagios 2.x
  • ndomod-3x.o = NDOMOD module for Nagios 3.x
  • ndomod-4x.o = NDOMOD module for Nagios 4.x
  1. Copy the compiled NDOMOD module to your Nagios installation:

    cp src/ndomod-4x.o /usr/local/nagios/bin/ndomod.o

    The command above assumes that you are using Nagios 4.x, and thus are installing the 4.x version of the NDOMOD module.

  2. Copy the sample NDOMOD config file to your Nagios installation after modifying it to suit your needs:

    cp config/ndomod.cfg /usr/local/nagios/etc
  3. Add a line similar to the following to the main Nagios config file (usually /usr/local/nagios/etc/nagios.cfg):

    broker_module=/usr/local/nagios/bin/ndomod.o config_file=/usr/local/nagios/etc/ndomod.cfg

    The config directive above will cause Nagios to load the NDOMOD event broker the next time it starts. Of course, this requires that you compiled Nagios with support for the event broker in the first place.

  4. Make sure you have a line similar to the following in the main Nagios config file (usually /usr/local/nagios/etc/nagios.cfg):


    That directive will cause the Nagios daemon to send data to the NDOMOD module. Without that option, NDOMOD won't get any information.

  5. NDOMOD processing options. Users can define which types of data are processed and stored by ndoutils. Each of these options can be defined in the ndomod.cfg file, and are considered a replacement for previous ndomod_processing_options config option, which used a bitmask. The following processing options are available.


Installing the Daemon

There are two different versions of the NDO2DB daemon that get compiled, so make sure you use the daemon that matches the version of Nagios you are running, and adjust the directions given below to fit the name of the daemon you're using.

  • ndo2db-2x = NDO2DB daemon for Nagios 2.x
  • ndo2db-3x = NDO2DB daemon for Nagios 3.x
  • ndo2db-4x = NDO2DB daemon for Nagios 4.x
  1. Copy the compiled NDO2DB daemon to your Nagios installation:

     cp src/ndo2db-4x /usr/local/nagios/bin/ndo2db

    The command above assumes that you are using Nagios 4.x, and thus are installing the 4.x version of the NDO2DB daemon.

  2. Copy the sample NDO2DB config file to your Nagios installation after modifying it to suit your needs (pay attention to the DB config settings).

     cp config/ndo2db.cfg /usr/local/nagios/etc
  3. Start the daemon! Depending your particular init system, it may look something like the following:

     service ndo2db start

Tuning Kernel Paramters

NDOUTILS uses a single message queue to communicate between the broker module and the NDO2DB daemon. Depending on the operating system, there may be parameters that need to be tuned in order for this communication to work correctly. The discussion below applies specifically to Linux, but may apply generally to other Unix operating systems as well.

There are three Linux kernel parameters that determine the resources provided to the messaging subsystem:

  • kernel.msgmax is the maximum size of a single message in a message queue
  • kernel.msgmni is the maximum number of messages allowed in any one message queue
  • kernel.msgmnb is the total number of bytes allow in all messages in any one message queue

To see the current values for any of these parameters, cat /proc/sys/kernel/msg{max|mni|mnb}.

In order for NDOUTILS to work at all, kernel.msgmax must be greater than the size of the queue_msg struct (currently 1026 bytes). Most Linux distributions set kernel.msgmax to a default of 65536.

If there are insufficient resources for sending messages between the broker and the daemon, you will see an entry similar to the following in your logs. (This is logged via the syslog facility, using the level LOG_ERR and the default facility.)

ndo2db: Warning: Retrying message send. This can occur because 
you have too few messages allowed or too few total bytes 
allowed in message queues. You are currently using 16 of 16 
mesages and 65536 of 65536 bytes in the queue.  See README for 
kernel tuning options.

If you see this entry, the message will likely eventually be sent, but retrying uses system resources, and there is the possibility that more messages will queued than can be handled, causing the broker module to stall.

If you are close to or have exceeded the number of messages, you may need to increase kernel.msgmni. If you are close to or have exceeded the number of bytes in the queue, you may need to increase kernel.msgmnb. In some cases you may need to increase both.

A conservative approach would be to double the necessary value, stop and restart both the NDO2DB daemon and Nagios Core, and watch for any further messages. Note that if NDO2DB is started after Nagios Core, you may see the warning above as the broker module first attempts to flush its backlog of messages.

To increase a value, echo the value to /proc/sys/kernel/msgmni or /proc/sys/kernel/msgmnb as appropriate.

For example, to increase the number of messages allowed in the queue to 32, use the command echo 32 > /proc/sys/kernel/msgmni.

Once you have determine the correct parameters, you can make them permanent by editing /etc/sysctl.conf. Add or update the line of the form kernel.msg{mni|mnb} = <value> with the value(s) determined above. The next time the system is booted, the values of the parameters in /etc/sysctl.conf will be loaded.

License Notice

NDOUtils - Nagios Data Output Utilities

Copyright (c) 1999-2009: Ethan Galstad

Copyright (c) 2009-2017: Nagios Core Development Team and Nagios Community Contributors

For detailed authorship information, refer to the source control management history and pay particular attention to commit messages and the THANKS file.

NDOUtils is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.

NDOUtils is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with NDOUtils. If not, see

Nagios and the Nagios logo are trademarks, servicemarks, registered trademarks or registered servicemarks owned by Nagios Enterprises, LLC. All other trademarks, servicemarks, registered trademarks, and registered servicemarks are the property of their respective owner(s).


If you have questions about this addon, or encounter problems getting things working along the way, your best bet for an answer or quick resolution is to check the Nagios Support Forums.