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Nagios Network Analyzer - My New Source Won’t Start

Problem Description

You added a new source, but it did not automatically start. Now the Source won't start.


Resolving The Problem

When creating a new Source in Network Analyzer it creates the directory structure - the folders where it will store flow data, the RRD data file, and the processes pid file. It also starts the Source (nfcapd or sfcapd) automatically once it's finished creating the new directories. Here's a couple reasons why it may not be starting.


The port selected is already bound by another Source or program

Since the nfcapd or sfcapd process is binding to a port, that port must be available.

If it's not then you will not be able to collect flow data or even start the processes. You can easily change the port from the Source page by clicking on the Edit tab and changing the port to a different one. Save the Source and start it.



The Source's directories are missing from the /usr/local/nagiosna/var/ directory

If Network Analyzer couldn't create the directory it normally means that it can't write to the parent directory.

Check the permissions of the /usr/local/nagiosna/var directory and make sure that it has user/group of nna/nnacmd and make sure the group has read/write access to the directory.

You may also need to make sure that the apache user and nna user are in the nnacmd group.



The nfcapd service is out of semaphores (semget() error in bookkeeper.c)

This is an issue that can occur if you have around 127 sources collecting information.

If suddenly your new sources will not start, please check your system messages log using the following command:

tail /var/log/messages


You are likely experiencing this problem if you see errors similar to the errors displayed in this picture:



Please note the 'semget' error line - this tells us that we are running low on semaphores. You can follow this guide to increase the amount of semaphores available to Nagios Network Analyzer - we recommend using 2-4 times more than you had previously in all fields.



The Python module rrdtool does not appear to be installed

When (re)starting the nagiosna service in a terminal session the following error is observed:

Traceback (most recent call last):
File "/usr/local/nagiosna/bin/initialize_source.py", line 16, in <module>
import rrdtool
ImportError: No module named rrdtool


This problem can be resolved by installing the rrdtool-python module the following command:


yum install -y rrdtool-python


Debian | Ubuntu

apt-get install -y python-rrdtool


Once installed restart the nagiosna service:


RHEL 7 + | CentOS 7 + | Debian | Ubuntu 16/18/20

systemctl restart nagiosna


The Source should now start


Additional Information

Get some more information from the backend log located in /usr/local/naigosna/var/backend.log which will show you python errors that may be causing the Source not to start. This is normally an indication that there is a bug and may need to be addressed by the support staff at the Nagios Support Forums.



Final Thoughts

For any support related questions please visit the Nagios Support Forums at:


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