PRTG Manual: Discovery Settings
When running a network discovery, there are many parameters you can specify to control exactly how the discovery behaves. Collectively, these parameters are called ‘discovery settings’. These settings let you control the following aspects of discovery:
▪What type of discovery should be run (Ping sweep or ARP crawl)?
▪What part of the network should be discovered?
▪What network protocols and credentials should be used to discover and interrogate devices?
▪What inventory information should be collected from Microsoft Windows devices?
▪Should UVexplorer try to ping devices before proceeding to use additional protocols to interrogate them?
▪Should IP addresses be resolved to their corresponding DNS host names?
▪Should UVexplorer capture device configurations for those that support them?
▪How many threads should be used to perform the discovery?
▪Which types of devices should be included in the discovery result?
Any time you run a discovery, you must select the discovery settings to be used for that discovery run. Typically, you will have different sets of discovery settings for performing different types of discoveries on your network. For example, while it is possible to discover your entire network in a single discovery, you might prefer to instead discover subsets of your network individually (e.g., by site or subnet), thus allowing quicker, more targeted collection of the information you need. Because you are discovering different parts of your network separately, you would need to create different settings for each discovery you want to run. Similarly, you might use different credentials on different parts of your network, thus requiring the creation of different discovery settings for different parts of your network. UVexplorer makes it easy to create and manage the discovery settings needed to run different discoveries on your network.
To manage your discovery settings, click the Discovery Settings icon on the Home toolbar. This will display the Discovery Settings form. This form lets you add, configure, and delete discovery settings. A list of all existing discovery settings is displayed on the left side of the form. The right side of the form displays properties of the currently-selected discovery settings.
To create new discovery settings, click on the Add icon (the plus sign) just above the discovery settings list on the left side of the form. Alternatively, you can right-click anywhere in the discovery settings list, and select Add from the context menu. This will cause new discovery settings with a default name to be created and selected. You can then edit the properties of the new discovery settings on the right side of the form.
Configuring Discovery Settings
The properties of a discovery settings object can be modified by first selecting it in the list of discovery settings. After it has been selected, the right side displays the various properties that can be edited. The following properties can be specified:
Name
Each discovery settings object must have a name, which can be anything you want, but cannot be empty.
Discovery Method
A discovery runs in two major phases: 1) Find devices on the network, and 2) Discover detailed information about each device. For the first phase, there are two major techniques for finding devices on a network: Ping Sweep and ARP Cache. The Discovery Method property specifies which of these two device discovery techniques you want to use. To help you select the one you want, both approaches are explained next.
▪Ping Sweep – Because you are familiar with your network’s structure, you know what subnets you have, and what IP address ranges are in use on your network. Of course, not all IP addresses in these ranges are currently in use, but some of them are. For a Ping Sweep discovery, you simply specify ranges of IP addresses that should be searched for devices, and UVexplorer will ping every address in those ranges to determine which addresses correspond to actual devices. The IP address ranges to be searched are specified in the ‘Seed IP Addresses / IP Ranges’ section. For Ping Sweep discoveries there are two things to keep in mind: 1) Ping Sweep only works on devices that can be successfully pinged. If your network or devices are configured to disallow ping, Ping Sweep will not work, 2) The more IP addresses that need to be pinged, the longer discovery will take. Specifying large IP address ranges can cause discovery to take a long time. Therefore, you should specify the smallest IP address ranges possible.
▪ARP Cache – The alternative to Ping Sweep is ARP Cache. Rather than doing a brute-force, exhaustive search of your IP address space as Ping Sweep does, an ARP Cache discovery intelligently discovers active IP addresses (and therefore devices) by inspecting the ARP caches on your network devices. To run an ARP Cache discovery, you must specify the IP addresses of one or more “seed devices”, which are the devices where the discovery will begin. The seed devices are typically your core network switches or other network devices that have large ARP caches containing IP addresses of other devices on your network. By interrogating the ARP caches on the seed devices, UVexplorer finds the IP addresses of other devices on your network. UVexplorer then interrogates the ARP caches on these other devices to obtain even more device IP addresses, and so on. In this way, UVexplorer crawls your network, and eventually finds most of the devices on your network. The IP addresses of the seed devices are specified in the ‘Seed IP Addresses / IP Ranges’ section. ARP Cache discoveries are typically faster than Ping Sweep discoveries, but they do require that SNMP be enabled on your network devices so that their ARP caches are accessible to UVexplorer.
Seed IP Addresses / IP Ranges
For Ping Sweep discoveries, this field is used to enter the IP address ranges that should be pinged. For ARP Cache discoveries, this field is used to enter the IP addresses of the seed devices that are used to initiate the discovery (typically core network devices). To specify the desired IP addresses, enter one or more lines in the text field, each of which should contain one of the following:
▪An individual IP address (e.g., 192.168.30.1)
▪An IP subnet consisting of an IP address and subnet mask length (in bits) separated by a forward slash (e.g., 172.16.0.0/24)
▪An IP address range consisting of minimum and maximum addresses separated by a dash (e.g., 10.0.0.32 – 10.0.0.96).
Pressing the ‘Default Gateway(s)’ button will automatically enter the IP addresses of the local computer’s IP gateways. Pressing the ‘Default Subnet(s)’ button will automatically enter the subnets that the local computer is a member of. Pressing the ‘Clear’ button will clear the text field.
Protocols / Credentials
This section lets you select the network protocols and credentials that should be used during discovery. It displays a list of all credentials that have been previously defined (see Managing Device Credentials for more information). The row for each credential contains a checkbox that you can check to select the credential. The checkbox in the table header can be used to easily select ALL credentials. When you select a credential, you are both telling UVexplorer to use that protocol during discovery, and which credential to use with that protocol. Only the selected protocols and credentials will be used during discovery.
You may select multiple credentials for the same protocol, in which case UVexplorer will try them all on each device until it finds one that works. The order of the credentials in the table is significant, because it determines the order in which UVexplorer tries the credentials during discovery. You can use the ‘Move Up’ and ‘Move Down’ buttons to select a credential, and move it up or down in the table.
The ‘Add’ button can be used to create new credentials, or modify existing credentials.
Windows Inventory Settings
UVexplorer uses the WMI protocol to collect inventory information from Windows devices. In order to collect WMI inventory, you must specify appropriate Windows(WMI) credentials. WMI data collection can be time-consuming, so this setting lets you specify how much WMI data to collect. If you select ‘Collect Basic Windows Inventory’, only basic WMI data will be collected. This will result in the fastest possible discovery. If you select ‘Collect Full Windows Inventory’, detailed WMI data will be collected. This will result in a slower discovery that produces much more detailed inventory information for Windows devices.
UVexplorer makes every effort to find all of the devices on your network. By default, it probes all IP addresses that it comes across during the discovery process in order to find as many devices as possible. This is often exactly what you want. However, sometimes you might want to discover only a subset of your network rather than the whole thing. Additionally, there might be good technical or management reasons to keep the discovery process out of certain parts of your network. In scenarios where you want to carefully control which parts of your network are discovered, you can use the Include Scopes and Exclude Scopes settings.
Include Scopes
The Include Scopes field can be used to specify precisely which IP addresses UVexplorer is allowed to discover. If specified, UVexplorer will discover ONLY IP addresses listed in this field.
Exclude Scopes
The Exclude Scopes field can be used to specify IP addresses that are off-limits during discovery. If specified, UVexplorer will discover all IP address EXCEPT the ones listed in this field.
Both of these fields may contain zero or more lines of text, each of which should contain one of the following:
▪An individual IP address (e.g., 192.168.30.1)
▪An IP subnet consisting of an IP address and subnet mask length (in bits) separated by a forward slash (e.g., 172.16.0.0/24)
▪An IP address range consisting of minimum and maximum addresses separated by a dash (e.g., 10.0.0.32 – 10.0.0.96).
This section contains a variety of advanced settings that you can specify. Each of them is described next.
Ping IPs/Devices First
For Ping Sweep discoveries, UVexplorer will always try to ping each device before trying to use other protocols to communicate with them. However, for ARP Cache discoveries you can use this setting to control whether or not UVexplorer will try to ping devices first. If your network and devices allow ping requests, enabling this option can result in faster discoveries (i.e., if UVexplorer can’t ping a device, it won’t bother trying other protocols on it, thus speeding things up). If your network and devices do not allow ping requests, disabling this option will allow UVexplorer to successfully discover your devices even though they can’t be pinged.
Resolve Hostnames
If this option is enabled, UVexplorer will resolve IP addresses to their corresponding DNS hostnames. This is done using reverse-DNS lookup.
Capture Device Configurations
UVexplorer can capture device configurations for many types of network devices (switches, routers, wireless APs, etc.). If this option is enabled, UVexplorer will attempt to retrieve configurations for all devices it can. Configuration capture is done using the SSH protocol. In order for this feature to work, you must specify SSH credentials for any devices for which you want configuration captures.
Max Threads
During a typical discovery, many devices need to be interrogated. To make discovery run as quickly as possible, UVexplorer works on many devices at the same time. However, discovering many devices at once can put more load on your network. Therefore, the ‘Max Threads’ setting can be used to precisely control the maximum number of devices that UVexplorer will communicate with concurrently. This lets you control the tradeoff between discovery speed and network load.
Exclude Categories
By default, UVexplorer will include all devices that it finds in the discovery result. Sometimes you might not be interested in certain kinds of devices, and prefer that they not be included in the result. The ‘Exclude Categories’ setting lets you enumerate specific categories of devices to be omitted from the discovery result. Each type of device you select will be dropped from the discovery result.
To delete an existing discovery settings object, select it in the discovery settings list on the left side of the form, and then click the Delete icon (with the red X) just above the list. Alternatively, you can right-click on the discovery settings in the list, and select Delete from the context menu. The deleted discovery settings should disappear from the list.
