# Auto discovery support

### Getting started with auto discovery.

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).

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.

#### 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';
```

If you want to enable / disable certain auto-discovery modules then see the rest of this doc for further info.

### Discovery methods

#### ARP
Disabled by default.

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.

#### 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.

#### 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';`