<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: Auto-Discovery
PRTG's auto-discovery function is a great way to automatically create a sophisticated and concise set of sensors for your complete network. It is mainly suitable for LAN discovery since it involves a lot of SNMP and WMI. For video instructions, please see the More section below.
Note: PRTG already runs a quick initial auto-discovery as soon as you finished the install of PRTG to automatically show you several available devices in your network.
PRTG's auto-discovery process has three stages:
- Step 1
Scanning a network segment for devices using Ping (for groups only). - Step 2
Assessing the device type for all devices discovered in Step 1 (using SNMP, WMI, and other protocols). - Step 3a
Creating sensor sets that match the discovered device types of step 2. This is done based on built-in device templates with recommended sensors for many device types.
Step 3b (optional)
Creating sensor sets using user created device templates (see Create Device Template section).
The auto-discovery can be used on a group level for a range of IP addresses, or for individual devices which you might have created manually. It can be run just once, on demand via the context menu, or scheduled every hour, day or week. Running the auto-discovery every day or week will automatically create new sensors when new devices are connected to the network. As soon as new devices or sensors are discovered, new Tickets are created (which are mailed to the system administrator by default).
Please be aware of the following restrictions of the auto-discovery:
- PRTG can not discover devices that can not be pinged, since Step 1 uses pings. If, for example, a firewall blocks echo requests, a device behind it cannot be discovered.
- Please define authentication settings for Windows Systems, Linux (SSH/WBEM) Systems, VMware/XEN Servers, Database Management Systems, Amazon Cloudwatch, and SNMP Devices to fully exploit the power of this feature. We recommend defining these in the Root group settings.
- If a device has more than one IP address, it may show up more than once in the discovery results, even though PRTG tries to identify these situations.
- If a device already exists on the same probe, the auto-discovery will skip this device and not create a duplicate.
- Using frequent auto-discoveries of large network segments can lead to performance issues. We therefore recommend to only schedule regular auto-discoveries where necessary. For detailed information see the More section below.
You can run an auto-discovery at any time for a group or a device. To do so, right-click on the object to analyze and select Run Auto-Discovery in the context menu. PRTG will immediately start searching for new objects which can be added to the device tree. If used for a group, PRTG will add devices and sensors, if found. If used for a device, it will add new sensors, if found. You can always see in the corresponding page header bar when the last auto-discovery was run on a selected group or device.
Note: The auto-discovery will also re-add devices or sensors you have manually deleted. If you do not want this, please create objects manually only.
Creating an Auto-Discovery Group
There are several ways to start auto-discovery:
- On the welcome screen, click on the Perform Network Auto-Discovery option,
- or select Devices | Add Auto-Discovery Group from the main menu.
To start an automatic detection of devices and sensors in your network an assistant will appear, leading you through two steps. For faster setup, you can select Add Auto-Discovery Group... in the context menu of a probe or group to which you want to add the new group. This will skip step 1 and lead you directly to step 2.
Note: This documentation refers to the PRTG System Administrator user accessing the Ajax interface on a master node. For other user accounts, interfaces, or nodes, not all of the options might be available as described. When using a cluster installation, failover nodes are read-only by default.

Add Auto-Discovery Group Dialog
- Step 1
Please choose a probe or group you want to add the new group to. Click on Continue.
- Step 2
Add auto-discovery settings as described below.
Add Auto-Discovery Group Settings
Group Name and Tags |
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Group Name |
Enter a meaningful name to identify the group. The name will be shown by default in the devices tree and in all alarms. |
Tags |
Enter one or more tags; confirm each tag by hitting the space, comma, or enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case sensitive. Tags are automatically inherited. |
Group Type |
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Sensor Management |
Select the method for automatic network discovery. Choose between:
|
Device Template(s) |
This option is only visible if using specific device templates (last option) is enabled above. Please choose one or more templates by adding a check mark in front of the respective template name. You can also select and deselect all items by using the check box in the table head. These will be used for auto-discovery on the current device. Choose from:
Once the auto-discovery is finished, PRTG will create a new ticket and list the device templates which were actually used to create new sensors. Templates which were not applied will not be shown in the ticket. |
Discovery Schedule |
Define when the auto-discovery will be run. Choose between:
|
IP Selection Method |
Define how you want to define the IP range for auto-discovery. Choose between:
Note: Only subnets with up to 65,536 IP addresses can be discovered! If you define a range with a higher number of addresses, discovery will stop before it is completed. |
IPv4 Base |
This field is only visible if Class C network detection is selected above. Enter a class C network as IP base for the auto-discovery. Enter the first three octets of an IPv4 IP address, for example, 192.168.0 |
IPv4 Range Start |
This field is only visible if Class C network detection is selected above. Enter the IP octet of the class C network specified above from which PRTG will start the auto-discovery. This will complete the IP base above to an IPv4 address. For example, enter 1 to discover from 192.168.0.1. |
IPv4 Range End |
This field is only visible if Class C network detection is selected above. Enter the IP octet of the class C network specified above at which PRTG will stop the auto-discovery. This will complete the IP base above to an IPv4 address. For example, enter 254 to discover up to 192.168.0.254. |
IPv4/DNS Name List |
This field is only visible if the IP list option is selected above. Enter a list of IP addresses or DNS names which the auto-discovery will scan. Enter each address in a separate line. |
IPv4 and Subnet (IPv4) |
This field is only visible if the IP and subnet option is selected above. Enter an expression in the format address/subnet, e.g. 192.168.3.0/255.255.255.0. You can also use the short form like 192.168.3.0/24 in this example. PRTG will scan the complete host range (without network and broadcast address) defined by the IP address and the subnet mask. |
IP with Octet Range |
This field is only visible if the octet range option is selected above. Enter an expression in the format a1.a2.a3.a4, where a1, a2, a3, and a4 are each a number between 0-255, or a range with two numbers and a hyphen like 1-127. All permutations of all ranges are calculated, e.g. 10.0.1-10.1-100 results in 1,000 addresses that PRTG will scan during auto-discovery. |
Organizational Unit |
This field is only visible if active directory is selected above. Enter an organizational unit (OU) to restrict the active directory search to computers which are part of this OU. Just enter the name of the OU without any other term (i.e., without "OU" in front). If you leave this field empty, there will not be any restriction. If you have sub-OUs, consider the correct syntax in the format Y,OU=X: OUs that are part of another OU have to be listed together with their parent(s). Enter the sub-OU followed by ,OU= and the name of the parent OU. Examples:
Note: The order is important, sub-OUs have to be listed left of their particular parents! |
Name Resolution |
Define how newly discovered devices will be monitored. This only affects new devices. The setting for existing devices will be kept. Choose between:
We recommend that you use the default value. |
Device Rescan |
Define if you want to rescan known devices. Choose between:
We recommend that you use the default value. |
By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting only for this object, disable inheritance by clicking on the check mark before the corresponding setting name. You will then see the options described below.
If you have not set credentials yet, set them now before starting the auto-discovery in order to fully exploit the power of this feature!
Credentials for Windows Systems |
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Domain or Computer Name |
Define the authority for Windows access. This is used for Windows Management Instrumentation (WMI) and other Windows sensors. If you want to use a Windows local user account on the target device, please enter the computer name here. If you want to use a Windows domain user account (recommended), please enter the (Active Directory) domain name here. If not explicitly defined, PRTG will automatically add a prefix in order to use the NT LAN Manager (NTLM) protocol. Please do not leave this field empty. |
User |
Enter the username for Windows access. Usually, you will use credentials with administrator privileges. |
Password |
Enter the password for Windows access. Usually, you will use credentials with administrator privileges. |
Credentials for Linux/Solaris/Mac OS (SSH/WBEM) Systems |
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User |
Enter a login name for the access via SSH and WBEM. Usually, you will use credentials with administrator privileges. |
Login |
Define the authentication method to use for login. Choose between:
|
Password |
This field is only visible if you select password login above. Enter a password for the Linux access via SSH and WBEM. Usually, you will use credentials with administrator privileges. |
Private Key |
This field is only visible if you select private key login above. Paste a private key into the field (OpenSSH format, unencrypted). Usually, you will use credentials with administrator privileges. Note: If you do not insert a private key for the first time, but change the private key, you need to restart your PRTG core server service in order for the private key change to take effect! For details, please see Monitoring via SSH. |
For WBEM Use Protocol |
Define the protocol to use for WBEM. This setting is only relevant if you use WBEM sensors. Choose between:
|
For WBEM Use Port |
Define the port to use for WBEM. This setting is only relevant if you use WBEM sensors. Choose between:
|
WBEM Port |
This setting is only visible if you enable manual port selection above. Enter the WBEM port number. |
SSH Port |
Enter the port number to use for SSH connections. Note: By default, PRTG uses this setting automatically for all SSH sensors, unless you define a different port number in the sensor settings. |
SSH Rights Elevation |
Define the rights with which you want to execute the command on the target system. Choose between:
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Target User |
This field is only visible if you choose sudo or su above. Enter a username to run the specified command as another user than root. If you leave this field empty, you will run the command as root. Ensure that you set the Linux password even if you use a public/private key for authentication. This is not necessary if the user is allowed to execute the command without a password. |
Password Target User |
This field is only visible if you choose su above. Enter the password for the specified target user. |
Credentials for VMware/XenServer |
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User |
Enter a login name for access to VMware and XEN servers. Usually, you will use credentials with administrator privileges. |
Password |
Enter a password for access to VMware and XEN servers. Usually, you will use credentials with administrator privileges. Note: Single Sign-On (SSO) passwords for vSphere do not support special characters. Please see the manual sections for VMware sensors for details. |
VMware Protocol |
Define the protocol used for the connection to VMware and XenServer. Choose between:
|
Session Pool |
Define if you want to use session pooling for VMware sensors. Choose between:
|
Credentials for Database Management Systems |
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The settings you define in this section apply to the following sensors: |
|
For Databases Use Port |
Define which ports PRTG will use for connections to the monitored databases. Choose between:
If you choose the automatic port selection, PRTG uses the following default ports:
|
Port |
Enter the number of the port that PRTG will use for database connections. Please enter an integer value. Note: All your database sensors will use this port to connect! |
Authentication |
Select the authentication method for the connection to the SQL database. Choose between:
|
User |
This field is only visible if you select SQL server authentication above. Enter the username for the database connection. |
Password |
This field is only visible if you selected SQL server authentication above. Enter the password for the database connection. |
Timeout (Sec.) |
Enter a timeout in seconds for the request. Please enter an integer value. If the reply takes longer than this value defines, the sensor cancels the request and triggers an error message. The maximum timeout value is 300 seconds (15 minutes). |
Credentials for Amazon CloudWatch |
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Access Key |
Enter your Amazon Web Services (AWS) Access Key. Please see the corresponding Amazon CloudWatch sensor documentation to know more about the rights that are required for querying AWS CloudWatch metrics. |
Secret Key |
Enter your Amazon Web Services (AWS) Secret Key. Please see the corresponding Amazon CloudWatch sensor documentation to know more about the rights that are required for querying AWS CloudWatch metrics. |
Credentials for SNMP Devices |
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SNMP Version |
Select the SNMP version for the device connection. Choose between:
Note for SNMP v3: Due to internal limitations you can only monitor a limited number of sensors per second using SNMP v3. The limit is somewhere between 1 and 50 sensors per second (depending on the SNMP latency of your network). This means that using an interval of 60 seconds you are limited to between 60 and 3000 SNMP v3 sensors for each probe. If you experience an increased "Interval Delay" or "Open Requests" with the Probe Health Sensor, you need to distribute the load over multiple probes. SNMP v1 and v2 do not have this limitation. |
Community String |
This setting is only visible if you select SNMP version v1 or v2c above. Enter the community string of your devices. This is a kind of "clear-text password" for simple authentication. We recommend that you use the default value. |
Authentication Type |
This setting is only visible if you select SNMP version v3 above. Choose between:
The type you choose must match the authentication type of your device. Note: If you do not want to use authentication, but you need SNMP v3, for example, because your device requires context, you can leave the field password empty. In this case, SNMP_SEC_LEVEL_NOAUTH is used and authentication deactivated entirely. |
User |
This setting is only visible if you select SNMP version v3 above. Enter a username for secure authentication. This value must match the username of your device. |
Password |
This setting is only visible if you select SNMP version v3 above. Enter a password for secure authentication. This value must match the password of your device. |
Encryption Type |
This setting is only visible if you select SNMP version v3 above. Select an encryption type. Choose between:
The type you choose must match the encryption type of your device. |
Data Encryption Key |
This setting is only visible if you select SNMP version v3 above. Enter an encryption key here. If you provide a key in this field, SNMP data packets are encrypted using the encryption algorithm selected above, which provides increased security. The key that you enter here must match the encryption key of your device. Note: If the key you enter in this field does not match the key configured on the target SNMP device, you will not get an error message about this! Please enter a string or leave the field empty. |
Context Name |
This setting is only visible if you select SNMP version v3 above. Enter a context name only if it is required by the configuration of the device. Context is a collection of management information accessible by an SNMP device. Please enter a string. |
SNMP Port |
Enter the port for the SNMP communication. We recommend that you use the default value. |
SNMP Timeout (Sec.) |
Enter a timeout in seconds for the request. If the reply takes longer than the value you enter here, the request is aborted and an error message triggered. |
Proxy Settings for HTTP Sensors |
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HTTP Proxy Settings |
The proxy settings determine how a sensor connects to a given URL. You can enter data for a proxy server that will be used when connecting via HTTP or HTTPS. Note: This setting is valid for the monitoring only and determines the behavior of sensors. In order to change proxy settings for the core server, please see System Administration—Core & Probes. |
Name |
Enter the IP address or DNS name of the proxy server to use. If you leave this field empty, no proxy will be used. |
Port |
Enter the port number of the proxy. Often, port 8080 is used. Please enter an integer value. |
User |
If the proxy requires authentication, enter the username for the proxy login. Note: Only basic authentication is available! Please enter a string or leave the field empty. |
Password |
If the proxy requires authentication, enter the password for the proxy login. Note: Only basic authentication is available! Please enter a string or leave the field empty. |
Access Rights |
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User Group Access |
Define which user group(s) will have access to the object that you edit. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:
You can create new user groups in the System Administration—User Groups settings. |
Click on the Continue button to store your settings. If you change tabs or use the main menu, all changes to the settings will be lost!
While auto-discovery is running you may experience a lower system performance as usual, because PRTG works in the background in order to discover your network. Depending on the IP ranges defined (up to 65,536 addresses) , the discovery may run up to several days before complete. You can review the status of the discovery process as follows:
- In the device tree, behind the group or device name, you will see a percentage value showing the progress of auto-discovery.
- During auto-discovery, the web interface will display a box in the lower right corner, showing the number of active auto-discovery tasks.
- In order to stop a running auto-discovery, right-click the group or device, and select Pause | For 5 minutes... from the context menu. Monitoring will be paused for 5 minutes, and auto-discovery tasks will be shut down.
Video Tutorial: There is a video available on the Paessler video tutorials page.
Knowledge Base: Why can automatic auto-discoveries evoke performance issues?
Other Ajax Web Interface Sections |
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Keywords: Auto-Discovery,Auto-Discovery Settings