librenms-librenms/doc/Developing/os/Initial-Detection.md

source: Developing/os/Initial-Detection.md

This document will provide the information you should need to add basic detection for a new OS.

Discovery

Discovery is now all done by yaml files, you do not and should not create a php file for discovery.

Create the new OS file which should be called includes/definitions/pulse.yaml. Here is a working example:

os: pulse
text: 'Pulse Secure'
type: firewall
icon: pulse
over:
    - { graph: device_bits, text: 'Device Traffic' }
    - { graph: device_processor, text: 'CPU Usage' }
    - { graph: device_mempool, text: 'Memory Usage' }
discovery:
    - sysObjectID:
        - .1.3.6.1.4.1.12532.

over: This is a list of the graphs which will be shown within the device header bar (mini graphs top right).

discovery: Here we are detecting this new OS using sysObjectID, this is the preferred method for detection. Other options are available:

• sysObjectID The preferred operator. Checks if the sysObjectID starts with one of the strings under this item
• sysDescr Use this in addition to sysObjectID if required. Check that the sysDescr contains one of the strings under this item
• sysObjectID_regex Please avoid use of this. Checks if the sysObjectID matches one of the regex statements under this item
• sysDescr_regex Please avoid use of this. Checks if the sysDescr matches one of the regex statements under this item
• snmpget Do not use this unless none of the other methods work. Fetch an oid and compare it against a value.
• _except You can add this to any of the above to exclude that element. As an example:

discovery:
    - 
      sysObjectID:
          - .1.3.6.1.4.1.12532.
      sysDescr_except:
          - 'Not some pulse'

group: You can group certain OS' together by using group, for instance ios, nx-os, iosxr are all within a group called cisco.

bad_ifXEntry: This is a list of models for which to tell LibreNMS that the device doesn't support ifXEntry and to ignore it:

 bad_ifXEntry:
     - cisco1941
     - cisco886Va
     - cisco2811

mib_dir: You can use this to specify the additional directories to look in for MIBs:

mib_dir:
    - juniper
    - cisco

poller_modules: This is a list of poller modules to either enable (1) or disable (0). Check includes/defaults.inc.php to see which modules are enabled/disabled by default.

poller_modules:
    cisco-ace-serverfarms: false
    cisco-ace-loadbalancer: false

discovery_modules: This is the list of discovery modules to either enable (1) or disable (0). Check includes/defaults.inc.php to see which modules are enabled/disabled by default.

discovery_modules:
     cisco-cef: true
     cisco-sla: true
     cisco-mac-accounting: false

Discovery Logic

YAML is converted to an array in PHP. Consider the following YAML:

discovery: 
  - sysObjectID: foo
  - 
    sysDescr: [ snafu, exodar ]
    sysObjectID: bar

This is how the discovery array would look in PHP:

[
     [
       "sysObjectID" => "foo",
     ],
     [
       "sysDescr" => [
         "snafu",
         "exodar",
       ],
       "sysObjectID" => "bar",
     ]
]

The logic for the discovery is as follows:

1. One of the first level items must match
2. ALL of the second level items must match (sysObjectID, sysDescr)
3. One of the third level items (foo, [snafu,exodar], bar) must match

So, considering the example:

• sysObjectID: foo, sysDescr: ANYTHING matches
• sysObjectID: bar, sysDescr: ANYTHING does not match
• sysObjectID: bar, sysDescr: exodar matches
• sysObjectID: bar, sysDescr: snafu matches

Discovery helpers

Within the discovery code base if you are using php then the following helpers are available:

$device['sysObjectID]: This will contain the full numerical sysObjectID for this device. $device['sysDescr']: This will contain the full sysDescr for this device.

Poller

OS polling is done within includes/polling/os/$os.inc.php and is where we detect certain values.

<?php

$version = preg_replace('/[\r\n\"]+/', ' ', snmp_get($device, "productVersion.0", "-OQv", "PULSESECURE-PSG-MIB"));
$hardware = "Juniper " . preg_replace('/[\r\n\"]+/', ' ', snmp_get($device, "productName.0", "-OQv", "PULSESECURE-PSG-MIB"));

$version: The version of the OS running on the device.

$hardware: The hardware version for the device. For example: 'WS-C3560X-24T-S'

$features: Features for the device, for example a list of cards in the slots of a modular chassis.

$serial: The main serial number of the device.

MIBs

If the device has MIBs available and you use it in the detection then you can add these in. It is highly recommended that you add mibs to a vendor specific directory. For instance HP mibs are in mibs/hp. Please ensure that these directories are specified in the yaml detection file, see mib_dir above.

Icon and Logo

It is highly recommended to use SVG images where possible, these scale and provide a nice visual image for users with HiDPI screens. If you can't find SVG images then please use png.

Create an SVG image of the icon and logo. Legacy PNG bitmaps are also supported but look bad on HiDPI.

• A vector image should not contain padding.
• The file should not be larger than 20 Kb. Simplify paths to reduce large files.
• Use plain SVG without gzip compression.
• The SVG root element must not contain length and width attributes, only viewBox.

Icon

• Save the icon SVG to html/images/os/$os.svg.
• Icons should look good when viewed at 32x32 px.
• Square icons are preferred to full logos with text.
• Remove small ornaments that are almost not visible when displayed with 32px width (e.g. ® or ™).

Logo

• Save the logo SVG to html/images/logos/$os.svg.
• Logos can be any dimension, but often are wide and contain the company name.
• If a logo is not present, the icon will be used.

Hints

Hints for Inkscape:

• You can open a PDF or EPS to extract the logo.
• Ungroup elements to isolate the logo.
• Use Path -> Simplify to simplify paths of large files.
• Use File -> Document Properties… -> Resize page to content… to remove padding.
• Use File -> Clean up document to remove unused gradients, patterns, or markers.
• Use File -> Save As -> Plain SVG to save the final image.

By optimizing the SVG you can shrink the file size in some cases to less than 20 %. SVG Optimizer does a great job. There is also an online version.

The final check

Discovery

./discovery.php -h HOSTNAME

Polling

./poller.php -h HOSTNAME

At this step we should see all the values retrieved in LibreNMS.

Note: If you have made a number of changes to either the OS's Discovery files, it's possible earlier edits have been cached. As such, if you do not get expected behaviour when completing the final check above, try removing the cache file first:

rm -f cache/os_defs.cache