Net-SNMP

Table of Contents

• Net-SNMP - Table of Contents
  • Overview
  • Module Description
  • Setup
    • What this module affects
    • Beginning with this module
    • Upgrading
      • Deprecation Warning
        • Past module 3.x series
        • Current module 4.x series
        • Future module 5.x series
  • Usage
    • Client
    • Trap Daemon
    • SNMPv3 Users
    • Access Control
      • Multiple Network Restrictions
  • Reference
  • Limitations
    • OS Support:
    • Notes:
    • Issues:
  • Development
    • Authors

Overview

This Puppet module manages the installation and configuration of Net-SNMP client, server, and trap server. It also can create a SNMPv3 user with authentication and privacy passwords.

Module Description

Simple Network Management Protocol (SNMP) is a widely used protocol for monitoring the health and welfare of network and computer equipment. Net-SNMP implements SNMP v1, SNMP v2c, and SNMP v3 using both IPv4 and IPv6. This Puppet module manages the installation and configuration of the Net-SNMP client, server, and trap server. It also can create a SNMPv3 user with authentication and privacy passwords.

Only platforms that have Net-SNMP available are supported. This module will not work with AIX or Solaris SNMP.

Setup

What this module affects

• Installs the Net-SNMP client package and configuration.
• Installs the Net-SNMP daemon package, service, and configuration.
• Installs the Net-SNMP trap daemon service and configuration.
• Creates a SNMPv3 user with authentication and encryption paswords.

Beginning with this module

This declaration will get you the SNMP daemon listening on the loopback IPv4 and IPv6 addresses with a v1 and v2c read-only community of 'public'.

include snmp

Upgrading

Deprecation Warning

Past module 3.x series

• The classes snmp::server and snmp::trapd have been merged into class snmp. All of their class parameters available in the snmp class.

Current module 4.x series

• The parameter install_client is renamed to manage_client.

• Support for Puppet < 4 is removed.

Future module 5.x series

• The parameters ro_community, rw_community, ro_network, and rw_network will be removed.

• The snmptrapd parameter name will become authcommunity.

Usage

Most interaction with the snmp module can be done through the main snmp class. This means you can simply toggle the parameters in ::snmp to have most functionality of the module. Additional fuctionality can be achieved by only utilizing the ::snmp::client class or the ::snmp::snmpv3_user define.

To install the SNMP service listening on all IPv4 and IPv6 interfaces:

class { 'snmp':
  agentaddress => [ 'udp:161', 'udp6:161' ],
}

To change the SNMP community from the default value and limit the netblocks that can use it:

class { 'snmp':
  agentaddress => [ 'udp:161', ],
  ro_community => 'myPassword',
  ro_network   => '192.168.0.0/16',
}

Or more than one community:

class { 'snmp':
  agentaddress => [ 'udp:161', ],
  ro_community => [ 'myPassword', 'myOtherPassword', ],
}

To set the responsible person and location of the SNMP system:

class { 'snmp':
  contact  => '[email protected]',
  location => 'Phoenix, Arizona, U.S.A., Earth, Milky Way',
}

Client

If you just want to install the SNMP client:

include snmp::client

To install the SNMP service and the client:

class { 'snmp':
  manage_client => true,
}

To install the SNMP service but not install the snmptrapd service

class { 'snmp':
  manage_snmptrapd => false,
}

If you want to pass client configuration stanzas to the snmp.conf file:

class { 'snmp':
  snmp_config => [
    'defVersion 2c',
    'defCommunity public',
    'mibdirs +/usr/local/share/snmp/mibs',
  ],
}

Trap Daemon

To only configure and run the snmptrap daemon:

class { 'snmp':
  service_ensure      => 'stopped',
  trap_service_ensure => 'running',
  trap_service_enable => true,
  snmptrapdaddr       => [ 'udp:162', ],
  trap_handlers       => [
    'default /usr/bin/perl /usr/bin/traptoemail [email protected]', # optional
    'TRAP-TEST-MIB::demo-trap /home/user/traptest.sh demo-trap', # optional
  ],
  trap_forwards       => [ 'default udp:55.55.55.55:162' ], # optional
}

SNMPv3 Users

To install a SNMP version 3 user for snmpd:

snmp::snmpv3_user { 'myuser':
  authpass => '1234auth',
  privpass => '5678priv',
}
class { 'snmp':
  snmpd_config => [ 'rouser myuser authPriv' ],
}

To install a SNMP version 3 user for snmptrapd:

snmp::snmpv3_user { 'myuser':
  authpass => 'SeCrEt',
  privpass => 'PhRaSe',
  daemon   => 'snmptrapd',
}

Access Control

With traditional access control, you can give a simple password and (optional) network restriction:

class { 'snmp':
  ro_community => 'myPassword',
  ro_network   => '10.0.0.0/8',
}

and it becomes this in snmpd.conf:

rocommunity myPassword 10.0.0.0/8

This says that any host on network 10.0.0.0/8 can read any SNMP value via SNMP versions 1 and 2c as long as they provide the password 'myPassword'.

With View-based Access Control Model (VACM), you can do this (more complex) configuration instead:

class { 'snmp':
  com2sec  => ['mySecName   10.0.0.0/8 myPassword'],
  groups   => ['myGroupName v1         mySecName',
               'myGroupName v2c        mySecName'],
  views    => ['everyThing  included   .'],
  accesses => ['myGroupName ""      any   noauth  exact  everyThing  none   none'],
}

where the variables have the following meanings:

• "mySecName": A security name you have selected.
• "myPassword": The community (password) for the security name.
• "myGroupName": A group name to which you assign security names.
• "everyThing": A view name (i.e. a list of MIBs that will be ACLed as a unit).

and it becomes this in snmpd.conf:

com2sec mySecName   10.0.0.0/8 myPassword
group   myGroupName v1         mySecName
group   myGroupName v2c        mySecName
view    everyThing  included   .
access  myGroupName ""      any   noauth  exact  everyThing  none   none

This also says that any host on network 10.0.0.0/8 can read any SNMP value via SNMP versions 1 and 2c as long as they provide the password 'myPassword'. But it also gives you the ability to change any of those variables.

Reference: Manpage of snmpd.conf - Access Control

Multiple Network Restrictions

In traditional access control, you can also pass multiple networks for the community string.

class { 'snmp':
  ro_community => 'shibboleth',
  ro_network   => [ '192.168.0.0/16', '1.2.3.4/32', ],
}

and it becomes this in snmpd.conf:

rocommunity shibboleth 192.168.0.0/16
rocommunity shibboleth 1.2.3.4/32

Reference

See in file REFERENCE.md.

Limitations

OS Support:

Net-SNMP module support is available with these operating systems:

• RedHat family - tested on CentOS 7
• SuSE family - tested on SLES 11 SP1
• Debian family - tested on Debian 8, Debian 9, Ubuntu 18.04, Ubuntu 20.04
• FreeBSD family - tested on FreeBSD 12.2 (uses ports/pkgng Net-SNMP, not system bsnmpd)
• Darwin family - tested on Darwin 18 (macOS 10.14 "Mojave"), 19 (macOS 10.15 "Catalina"), and 20 (macOS 11.1 "Big Sur").

Notes:

• By default the SNMP service now listens on BOTH the IPv4 and IPv6 loopback addresses.
• There is a bug on Debian squeeze of net-snmp's status script. If snmptrapd is not running the status script returns 'not running' so puppet restarts the snmpd service. The following is a workaround: class { 'snmp': service_hasstatus => false, trap_service_hasstatus => false, }
• For security reasons, the SNMP daemons are configured to listen on the loopback interfaces (127.0.0.1 and [::1]). Use agentaddress and snmptrapdaddr to change this configuration.
• Not all parts of Traditional Access Control or VACM Configuration are fully supported in this module.

Issues:

• Debian will not support the use of non-numeric OIDs. Something about rabid freedom.
• Figure out how to install the RFC-standard MIBS on Debian so that snmpwalk -v 2c -c public localhost system will function.
• Possibly support USM and VACM?

Development

This module is maintained by Vox Pupuli. Voxpupuli welcomes new contributions to this module. We are happy to provide guidance if necessary.

Please see CONTRIBUTING.md for information on how to contribute.

Authors

• Mike Arnold [email protected]
• Vox Pupuli Team
• List of contributors https://github.com/voxpupuli/puppet-snmp/graphs/contributors

Licensed under the Apache License, Version 2.0.