Table of Contents

1 Network discovery

Overview

Zabbix offers automatic network discovery functionality that is effective and very flexible.

With network discovery properly set up you can:

Zabbix network discovery is based on the following information:

It does NOT provide:

Network discovery basically consists of two phases: discovery and actions.

Discovery

Zabbix periodically scans the IP ranges defined in network discovery rules. The frequency of the check is configurable for each rule individually.

Note that one discovery rule will always be processed by a single discoverer process. The IP range will not be split between multiple discoverer processes.

Each rule has a set of service checks defined to be performed for the IP range.

Discovery checks are processed independently from the other checks. If any checks do not find a service (or fail), other checks will still be processed.

Every check of a service and a host (IP) performed by the network discovery module generates a discovery event.

EventCheck of service result
Service Discovered The service is 'up' after it was 'down' or when discovered for the first time.
Service Up The service is 'up', consecutively.
Service Lost The service is 'down' after it was 'up'.
Service Down The service is 'down', consecutively.
Host Discovered At least one service of a host is 'up' after all services of that host were 'down' or a service is discovered which belongs to a not registered host.
Host Up At least one service of a host is 'up', consecutively.
Host Lost All services of a host are 'down' after at least one was 'up'.
Host Down All services of a host are 'down', consecutively.

Actions

Discovery events can be the basis of relevant actions, such as:

These actions can be configured with respect to the device type, IP, status, uptime/downtime, etc. For full details on configuring actions for network-discovery based events, see action operation and conditions pages.

Linking a discovered host to templates will fail collectively if any of the linkable templates has a unique entity (e.g. item key) that is the same as a unique entity (e.g. item key) already existing on the host or on another of the linkable templates.
Host creation

A host is added if the Add host operation is selected. A host is also added, even if the Add host operation is missing, if you select operations resulting in actions on a host. Such operations are:

Created hosts are added to the Discovered hosts group (by default, configurable in AdministrationGeneralOther). If you wish hosts to be added to another group, add a Remove from host groups operation (specifying “Discovered hosts”) and also add an Add to host groups operation (specifying another host group), because a host must belong to a host group.

Host naming

When adding hosts, a host name is the result of reverse DNS lookup or IP address if reverse lookup fails. Lookup is performed from the Zabbix server or Zabbix proxy, depending on which is doing the discovery. If lookup fails on the proxy, it is not retried on the server. If the host with such a name already exists, the next host would get _2 appended to the name, then _3 and so on.

It is also possible to override DNS/IP lookup and instead use an item value for host name, for example:

If the host name has been set using an item value, it is not updated during the following discovery checks. If it is not possible to set host name using an item value, default value (DNS name) is used.

If a host already exists with the discovered IP address, a new host is not created. However, if the discovery action contains operations (link template, add to host group, etc), they are performed on the existing host.

Host removal

Hosts discovered by a network discovery rule are removed automatically from MonitoringDiscovery if a discovered entity is not in the rule's IP range any more. Hosts are removed immediately.

Interface creation when adding hosts

When hosts are added as a result of network discovery, they get interfaces created according to these rules:

Changing proxy setting

The hosts discovered by different proxies are always treated as different hosts. While this allows to perform discovery on matching IP ranges used by different subnets, changing proxy for an already monitored subnet is complicated because the proxy changes must be also applied to all discovered hosts.

For example the steps to replace proxy in a discovery rule:

  1. disable discovery rule
  2. sync proxy configuration
  3. replace the proxy in the discovery rule
  4. replace the proxy for all hosts discovered by this rule
  5. enable discovery rule