How to Install Nagios 4.3.4 on RHEL, CentOS and Fedora

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Ravi Saive

I am Ravi Saive, creator of TecMint. A Computer Geek and Linux Guru who loves to share tricks and tips on Internet. Most Of My Servers runs on Open Source Platform called Linux. Follow Me: Twitter, Facebook and Google+

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403 Responses

  1. Raju says:


    I installed the Nagios and everything goes okay but when i open it browser in Google Chrome it show this message

    Not Found
    The requested URL /nagios was not found on this server.

    What can i do now?

    • Ravi Saive says:


      It’s clear that your Nagios installation wasn’t successful, try to follow Nagios installation instructions carefully..

  2. Aldo says:

    someone nows how to monitor a router that is out off my local network?

  3. Arjun says:

    Reusing existing connection to
    HTTP request sent, awaiting response… 404 Not Found
    2017-12-24 01:19:38 ERROR 404: Not Found.

  4. shuja says:

    getting below error while running above command

    /usr/local/nagios/etc/nagios.cfg: line 1144: syntax error near unexpected token `|’
    /usr/local/nagios/etc/nagios.cfg: line 1144: `illegal_macro_output_chars=`~$&|'”‘

  5. Bharath HJ says:

    From command line [using links] I am able to access nagios, but the same fails when I try to hit the URL from a remote host.

    When trying to access nagios from remote host via browser, after entering credentials for nagiosadmin on browser- receiving a blank page [connection reset]. Log shows that it might be failing to load main.php and side.php after user authorization.
    Any suggestions please on what can be the issue?

    Troubleshooting steps tried so far:
    – Able to access a static php from remote host via browser
    – Tried from different browsers [Mozilla, Chrome, IE]
    – Able to telnet from remote host to server [Port 80]
    – Provided all access to files [/usr/local/nagios/etc/htpasswd.users, /usr/local/nagios/share/main.php, side.php]
    – Both server and remote hosts are on the same timezone
    – HTTP is running as user -apache

    Versions installed: nagios-4.3.4, nagios-plugins-2.2.1
    OS: RHEL 6.9
    Packages installed: httpd, httpd-tools, php, gcc, glibc, glibc-common, gd, gd-devel, make, net-snmp

    Logs when accessing on local using command line [links]
    [23/Nov/2017:09:34:34 +0000] “GET /nagios HTTP/1.1” 401 482 “-” “Links (2.13; Linux; GNU C 4.4.7; text)”
    nagiosadmin [23/Nov/2017:09:34:42 +0000] “GET /nagios HTTP/1.1” 301 318 “-” “Links (2.13; Linux; GNU C 4.4.7; text)”
    nagiosadmin [23/Nov/2017:09:34:42 +0000] “GET /nagios/ HTTP/1.1” 200 1079 “-” “Links (2.13; Linux; GNU C 4.4.7; text)”
    nagiosadmin [23/Nov/2017:09:34:42 +0000] “GET /nagios/side.php HTTP/1.1” 200 4735 “http://xx.xx.xx.xx/nagios/” “Links (2.13; Linux; GNU C 4.4.7; text)”
    nagiosadmin [23/Nov/2017:09:34:42 +0000] “GET /nagios/main.php HTTP/1.1” 200 7993 “http://xx.xx.xx.xx/nagios/” “Links (2.13; Linux; GNU C 4.4.7; text)”

    Logs when accessing from remote host.
    [23/Nov/2017:09:59:31 +0000] “GET /nagios HTTP/1.1” 401 482 “-” “Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0”
    nagiosadmin [23/Nov/2017:09:59:39 +0000] “GET /nagios HTTP/1.1” 301 318 “-” “Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0”

    • Ravi Saive says:


      Please check the firewall rules, something is blocking accessing from remote host..

      • Bharath HJ says:

        Thanks Ravi,

        I did check firewall rules and they are disabled.
        Though I am still unable to connect to console after entering nagiosadmin credentials.

        Current status on nagios server::
        # /sbin/service iptables status
        iptables: Firewall is not running.
        # sestatus
        SELinux status: disabled
        # /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
        Nagios Core 4.3.4
        Copyright (c) 2009-present Nagios Core Development Team and Community Contributors
        Copyright (c) 1999-2009 Ethan Galstad
        Last Modified: 2017-08-24
        License: GPL
        Reading configuration data…
        Read main config file okay…
        Read object config files okay…
        Running pre-flight check on configuration data…
        Checking objects…
        Checked 8 services.
        Checked 1 hosts.
        Checked 1 host groups.
        Checked 0 service groups.
        Checked 1 contacts.
        Checked 1 contact groups.
        Checked 24 commands.
        Checked 5 time periods.
        Checked 0 host escalations.
        Checked 0 service escalations.
        Checking for circular paths…
        Checked 1 hosts
        Checked 0 service dependencies
        Checked 0 host dependencies
        Checked 5 timeperiods
        Checking global event handlers…
        Checking obsessive compulsive processor commands…
        Checking misc settings…
        Total Warnings: 0
        Total Errors: 0
        Things look okay – No serious problems were detected during the pre-flight check

        Not sure why I am able to access a static php from my remote host hosted using the same httpd.conf on the nagios server, but unable to hit /nagios.

        It does prompt for user credentials but does not load the nagios console.

  6. imtiyaj says:

    Dear Sir,

    Thank you for valuable. Nagios configuration is done properly. Please help to how to add servers and services in Nagios.

    How to create Nagios database ? In new configure Nagios, no database was created in Mysql.

  7. shuja says:


    I installed and configured Nagios but my localhost is showing down. can u tell me how to bring it up or into monitoring

    • Ravi Saive says:


      Please verify Nagios configuration for errors using following command, if any errors shown, fix it accordingly.

      # /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
      • shuja says:

        /usr/local/nagios/etc/nagios.cfg: line 1144: syntax error near unexpected token `|’
        /usr/local/nagios/etc/nagios.cfg: line 1144: `illegal_macro_output_chars=`~$&|’”‘

  8. imtiyaj says:

    Dear Sir,

    Thank you for information. Please share information about how to add hosts and it’s respective services in Nagios latest version.

  9. Arun Mohan says:

    thanks…its working fine

  10. Umer says:

    All installation steps goes fine.

    When I execute command systemctl enable nagios it shows error.

    Failed to execute operation: Access denied

    please help as soon as possible.

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