source: Extensions/Auto-Discovery.md
# Auto Discovery Support

### Getting Started

LibreNMS provides the ability to automatically add devices on your network, we can do this with via
a few methods which will be explained below and also indicate if they are enabled by default.

All discovery methods run when discovery.php runs (every 6 hours by default and within 5 minutes for new devices).

> Please note that you need at least ONE device added before auto-discovery will work.

The first thing to do though is add the required configuration options to `config.php`.

### SNMP Details

To add devices automatically we need to know your snmp details, examples of SNMP v1, v2c and v3 are below:

```php
// v1 or v2c
$config['snmp']['community'][] = "my_custom_community";
$config['snmp']['community'][] = "another_community";

// v3
$config['snmp']['v3'][0]['authlevel'] = 'AuthPriv';
$config['snmp']['v3'][0]['authname'] = 'my_username';
$config['snmp']['v3'][0]['authpass'] = 'my_password';
$config['snmp']['v3'][0]['authalgo'] = 'MD5';
$config['snmp']['v3'][0]['cryptopass'] = 'my_crypto';
$config['snmp']['v3'][0]['cryptoalgo'] = 'AES';
```

These details will be attempted when adding devices, you can specify any mixture of these.

### Allowed Networks
#### Your Networks

To add devices, we need to know what are your subnets so we don't go blindly attempting to add devices not
under your control.

```php
$config['nets'][] = '192.168.0.0/24';
$config['nets'][] = '172.2.4.0/22';
```

### Exclusions

If you have added a network as above but a single device exists within it that you can't auto
add, then you can exclude this with the following:

```php
$config['autodiscovery']['nets-exclude'][] = '192.168.0.1/32';
```

## Additional Options
#### Discovering devices by IP

By default we don't add devices by IP address, we look for a reverse dns name to be found and add with that. If this fails
and you would like to still add devices automatically then you will need to set `$config['discovery_by_ip'] = true;`

#### Short hostnames

If your devices only return a short hostname such as lax-fa0-dc01 but the full name should be lax-fa0-dc01.example.com then you can
set `$config['mydomain'] = 'example.com';`

#### Allow Duplicate sysName

By default we require unique sysNames when adding devices (this is returned over snmp by your devices). If you would like to allow
devices to be added with duplicate sysNames then please set `$config['allow_duplicate_sysName'] = true;`.


## Discovery Methods
Below are the methods for auto discovering devices.  Each one can be enabled or disabled and may have additional configuration options.

### ARP
Disabled by default.

Adds devices that are listed in another device's arp table.  This module depends on the arp-table module being enabled and returning data.

To enable, switch on globally the `$config['discovery_modules']['discovery-arp'] = 1;` or per device within the Modules section.

### XDP
Enabled by default.

`$config['autodiscovery']['xdp'] = false;` to disable.

This includes FDP, CDP and LLDP support based on the device type.

Devices may be excluded from xdp discovery by sysName and sysDescr.

```php
//Exclude devices by name
$config['autodiscovery']['xdp_exclude']['sysname_regexp'][] = '/host1/';
$config['autodiscovery']['xdp_exclude']['sysname_regexp'][] = '/^dev/';

//Exclude devices by description
$config['autodiscovery']['xdp_exclude']['sysdesc_regexp'][] = '/Vendor X/';
$config['autodiscovery']['xdp_exclude']['sysdesc_regexp'][] = '/Vendor Y/';
```

Devices may be excluded from cdp discovery by platform.

```php
//Exclude devices by platform(Cisco only)
$config['autodiscovery']['cdp_exclude']['platform_regexp'][] = '/WS-C3750G/';
```

These devices are excluded by default:

```php
$config['autodiscovery']['xdp_exclude']['sysdesc_regexp'][] = '/-K9W8-/'; // Cisco Lightweight Access Point
$config['autodiscovery']['cdp_exclude']['platform_regexp'][] = '/^Cisco IP Phone/'; //Cisco IP Phone
```

### OSPF
Enabled by default.

`$config['autodiscovery']['ospf'] = false;` to disable.

### BGP
Enabled by default.

`$config['autodiscovery']['bgp'] = false;` to disable.

This module is invoked from bgp-peers discovery module.

## SNMP Scan
This isn't actually an auto-discovery mechanism, but manually invoked.

It's designed to scan through all of the subnets in your config or what you have manually specified
to automatically add devices.

SNMP Scan will scan `$config['nets']` by default and respects `$config['autodiscovery']['nets-exclude']`.

An example of it's usage is:

```bash
./snmp-scan.py -r 192.168.0.0/24
```

