SNMP

Introduction

Simple Network Management Protocol (SNMP) is an application-layer protocol defined by the Internet Architecture Board (IAB) for exchanging management information between network devices. It is a part of the Transmission Control Protocol/Internet Protocol (TCP⁄IP) suite.

SNMP is one of the widely accepted protocols to manage and monitor network elements. Most of the professional-grade network elements come with bundled SNMP agent. These agents have to be enabled and configured to communicate with the network management system (NMS). The SNMP agent is a program that resides on your managed device, packaged within the network element. You have to enable it on your device. It collects the management information from the device locally and provides it to the SNMP manager. These agents could be standard, for example, Net-SNMP or specific to a vendor, such as HP Insight Agent.

SNMP Credentials

SNMP uses a password-like authorization known as a community string. When you provide an SNMP credential to a device, it checks to see if the community string matches the community string configured on the device. If the string matches, the device responds to the SNMP query.

Discover the gateway using SNMP

To find the read-only gateway community string, one option is to:

1. Log into the gateway WebUI.
2. Click SNMP.

Or, you can get the read-only community string by logging into the gateway and reading the string in the /etc/snmp/snmpd.conf file.

You can change the community string to a name of your choice.

Multi-credential functionality

SNMP multi-credential functionality allows you to discover network resources using multiple credentials using a single discovery profile. You can create or use multiple credential sets if you are using a gateway to discover your resources.

For example, a printer uses SNMPv2c credential type and a Cisco router uses SNMPv3 credential type. In such a case, you need to create two discovery profiles. With SNMP multi-credential functionality, you can create one discovery profile and use both the credential sets.

The gateway discovers devices with the credentials, sequentially, as the credentials were entered when a Discovery Profile was created at the time of the first scan. After successful discovery, the gateway remembers resources and their credentials for subsequent discovery.

Multi-credentialed, SNMP-enabled devices have the following advantages:

• Reduces the effort of creating multiple discovery profiles.
• Reduces time for manually traversing through multiple discovery profiles to discover a network resource.
• Scans and discovers a subnet with multiple SNMP community strings.
• Discovers network resources working on different SNMP versions.

SNMP field values

The following provides information on configuring the SNMP fields for creating an SNMP credential set.

SNMPv1 and SNMPv2

SNMPv3

SNMPv3 is a user-based security model. It provides secure access to the devices by combining authenticating and encrypting packets over the network. The security features provided in SNMPv3 are message integrity, authentication, and encryption.

Configure and Install the Integration

1. From All Clients, select a client.

2. Go to Setup > Account.

3. Select the Integrations and Apps tab.

4. The Installed Integrations page, where all the installed applications are displayed.
   Note: If there are no installed applications, it will navigate to the ADD APP page.

5. Click + ADD on the Installed Integrations page. The Available Integrations and Apps page displays all the available applications along with the newly created application with the version.
   Note: You can even search for the application using the search option available. Also you can use the All Categories option to search.

   

6. Click ADD on the SNMP tile.

7. From the Configurations page, click + ADD.

8. Enter the below mentioned BASIC INFORMATION:

   • Name: Enter the name for the integration.

   • Profile Type (Note: We support Cisco and Aruba WLAN Controllers only): Select any Profile Type.

     • SNMP Network Device
     • WLAN AP
     • WLAN Controller
     • Network Cloud Controller

     Note: Based on the profile type selected, the fields for input change.

   

SNMP Network Device

If you selected SNMP Network Device as profile type, provide inputs for the following fields:

• Credentials: Select a credential from the drop-down list. This credential refers to the access, authorization, or authentication credentials assigned to your devices managed by the network administrators.
  • (Optional) Click + Add to create a credential. The ADD CREDENTIAL window is displayed. Enter the following information.
    • Name: Credential name.
    • Description: Brief description of the credential.
    • SNMP Version: Select a version. Default is V1. Click here for more information.
    • Port: Enter the port. Default is 161. Click here for more information.
    • Community: Enter the community string. Default is public. Click here for more information.
    • Connection Timeout(ms): Specify the connection timeout in milliseconds. Click here for more information.
  • Discovery Type: Select the discovery type from the list:
    • IP Range: Select this option if you have an IP range and enter all the IP addresses in the box separated by a comma, or enter a range of IP addresses to be discovered.
    • Seed: Enter the IP address of the root or the seed device. Seed IP defines the range of IP addresses where network discovery starts a scan. When a seed IP is defined, the root device and the adjacent neighbors of the root device are scanned.
      • Depth: Select the depth from the drop-down list. The devices are scanned at a depth starting from the IP of the root device. Depth defines the level of the network you want to scan. Example: Depth 1 indicates the seed or the root device and its immediate neighbors. Depth 2 indicates seed or the root device including its immediate neighbors and their immediate neighbors.
      • Seed IPs: Enter the IP address of the root or the seed device. Seed IP defines the range of IP addresses where network discovery starts a scan. When a seed IP is defined, the root device and the adjacent neighbors of the root device are scanned.
      • Include Subnet: Select this option if you want to discover devices of a specific subnet. To discover a specific subnet in the Seed IP, enter the subnet IP in CIDR format. Example: You want to discover devices from IPs 172.24.22.0 to 172.24.22.255 in a subnet, provide IP in CIDR format as 172.24.22.0/24.
      • Exclude Subnet: Select this option if you want to discover devices excluding those of a specific subnet. To exclude discovery of a specific subnet in the Seed IP, enter the subnet IP in CIDR format. Example, you want to exclude IPs 172.24.22.0 to 172.24.22.255 in a subnet, provide IP in CIDR format as 172.24.22.0/24.

WLAN AP

If you selected WLAN AP as profile type, provide inputs for the following fields:

• Credentials: Select a credential from the drop-down list. This credential refers to the access, authorization, or authentication credentials assigned to your devices managed by the network administrators.
  • (Optional) Click + Add to create a credential. The ADD CREDENTIAL window is displayed. Enter the following information.
    • Name: Credential name.
    • Description: Brief description of the credential.
    • SNMP Version: Select a version. Default is V1. Click here for more information.
    • Port: Enter the port. Default is 161. Click here for more information.
    • Community: Enter the community string. Default is public. Click here for more information.
    • Connection Timeout(ms): Specify the connection timeout in milliseconds. Click here for more information.
  • IP Address: Enter the IP address.
  • Monitor Access Points: Select this checkbox, if you want to monitor the access points. Select the frequency (in minutes). The access points monitoring data for the selected frequency will be displayed on the device details page.

WLAN Controller

If you selected WLAN Controller as profile type, provide inputs for the following fields:

• Credentials: Select a credential from the drop-down list. This credential refers to the access, authorization, or authentication credentials assigned to your devices managed by the network administrators.
  • (Optional) Click + Add to create a credential. The ADD CREDENTIAL window is displayed. Enter the following information.
    • Name: Credential name.
    • Description: Brief description of the credential.
    • SNMP Version: Select a version. Default is V1. Click here for more information.
    • Port: Enter the port. Default is 161. Click here for more information.
    • Community: Enter the community string. Default is public. Click here for more information.
    • Connection Timeout(ms): Specify the connection timeout in milliseconds. Click here for more information.
  • IP Address: Enter the IP address.

Network Cloud Controller

If you selected Network Cloud Controller as profile type, provide inputs for the following fields:

• Credentials: Select a credential from the drop-down list. This credential refers to the access, authorization, or authentication credentials assigned to your devices managed by the network administrators.
  • (Optional) Click + Add to create a credential. The ADD CREDENTIAL window is displayed. Enter the following information.
    • Name: Credential name.
    • Description: Brief description of the credential.
    • SNMP Version: Select a version. Default is V1. Click here for more information.
    • Port: Enter the port. Default is 161. Click here for more information.
    • Community: Enter the community string. Default is public. Click here for more information.
    • Connection Timeout(ms): Specify the connection timeout in milliseconds. Click here for more information.
  • IP Address: Enter the IP address.

7. From the PERFORM ACTIONS section, choose Manage Device to set the resources as managed.
8. From the FILTER BY QUERY, click + QUERY and select the Attributes, Operator, or use </> to enter the Input query.
9. In the DISCOVERY SCHEDULE section, select recurrence pattern to add one of the following patterns:
   • Minutes
   • Hourly
   • Daily
   • Weekly
   • Monthly
10. Click ADD.

Now the configuration is saved and displayed on the configurations page after you save it. Note: From the same page, you may Edit and Remove the created configuration.

11. Click NEXT.

12. (Optional) Click +ADD to create a new collector by providing a name or use the pre-populated name.

    

13. Select an existing registered profile.

14. Click FINISH.

The application is now installed and displayed on the Installed Integration page. Use the search field to find the installed application.

Modify the Installed Integration

• See Modify an Installed Integration or Application article.

  Note: Select the SNMP application.

SNMP Definition Requests

You can view and submit SNMP definitions for review.

Only Service Provider (SP) and partner-level users can submit SNMP definition requests. All user levels, including SP, partner, and client, can view existing definitions.

View SNMP definition requests

1. Go to Setup > Resources.
2. Click SNMP Device Type Definitions. This displays the list of available definitions, as shown in the example:

Submit SNMP definition request

1. Go to Setup > Resources.

2. Click SNMP Device Type Definitions.

3. Click the +Submit button.

4. In the Add SNMP Device Type Definition page, enter the following information:

   Device Type Definition:

   Field	Required	Description
   Object OID	Yes	Object identifier.
   Make	Yes	Choose the make from the drop-down list.
   Model	No	If you selected Model, choose the model from the drop-down list.
   Model OID	No	If you selected Model OID, enter a model identifier.
   Device Type	Yes	Choose a device type from the drop-down list.
   Operating System	Yes	Choose an operating system from the drop-down list.
   Serial Number OID	No	Serial number identifier.
   Firmware Revision OID	No	Firmware revision identifier.
   Hardware Revision OID	No	Hardware revision identifier.
   Software Revision OID	No	Software revision identifier.

   SNMP OIDs for Network Interface Information:

   Field	Required
   Number of Interfaces	No
   Name	No
   Alias	No
   Index	No
   Type	No
   Speed	No
   Operational Status	No
   Admin Status	No

5. Click Cancel to discard your definition or click Submit, which displays the following advisory message:

   This definition will reflect on devices only after it is reviewed by a vistara admin. You can check the status on the definition listing page.

6. Click Yes to continue and submit your definition for review.

SNMP Discovery Troubleshooting Steps

1. Unable to see the discovered devices under discovery profiles?

   Device should be enabled with SNMP protocol or device should be reachable from the gateway

2. How to check the device reachable?

   Command

       ping <ipaddress>
       

3. If the device is enabled with SNMP, then make sure whether the device responds to SNMP.

   SNMP version 1:

   Basic Syntax

       snmpwalk -v1 -c <community> <ipaddress> <OID>
       

   Example: snmpwalk -v1 -c community 10.10.10.10 1.3.6.1.2.1.1
   
   
   SNMP version 2:

   Basic Syntax

       snmpwalk -v2c -c <community> <ipaddress> <OID>
       

   Example: snmpwalk -v2c -c community 10.10.10.10 1.3.6.1.2.1.1
   
   
   SNMP version 3:

   Basic Syntax

       snmpwalk -v3 -l <noAuthNoPriv|authNoPriv|authPriv> -u <username> -a <MD5|SHA> -A <MD5|SHA key> -x <DES|AES> -X <DES|AES key> -n <context> <ipaddress> <OID>
       

   Example: snmpwalk -v3 -l authPriv -u user4 -a MD5 -A 1234567890abcdef -x DES -X 1234567890abcdef 10.197.1.1 1.3.6.1.2.1.1
   
   

4. Unable to see the discovered devices under discovery profiles even snmp is working?

   • If the SNMPwalk command is functioning correctly, it is essential to verify the SNMPget command as well. This is crucial as we rely on the SNMPget command to retrieve information from the Netscaler.

   Basic Syntax

       snmpget -v2c -c <community> <ipaddress>
       

   Example: snmpget -v2c -c Ac-5nmp! 192.168.147.26 1.3.6.1.2.1.1.5.0
   
   

   • If SNMPwalk is operational but the SNMPget command is not functioning, resulting in request timeouts, credentials cannot be obtained. Without valid credentials, device discovery using SNMP becomes impossible. Therefore, it is imperative to ensure the functionality of both commands.

   • If the device responds to SNMP, it is crucial to confirm that the SNMP credentials utilized align with those assigned in the discovery profile. The SNMP credentials eliciting a response from the device should precisely match the credentials specified in the SNMP discovery profile.

   • Ensure that the correct gateway selected in the discovery profile is being utilized.

   • If SNMPv3 credentials are in use and a context name is specified in the credentials, it is important to note that when checking SNMPwalk or SNMPget commands from the gateway, the context name must be explicitly included in the command. In the event of a request timeout, it is advised to remove the context name from the credentials and initiate a re-discovery process.

   Syntax

       snmpwalk -v3 -l <noAuthNoPriv|authNoPriv|authPriv> -u <username> -a <MD5|SHA> -A <MD5|SHA key> -x <DES|AES> -X <DES|AES key> -n <context> <ipaddress> <OID>
       

   Note:In general context is used to differentiate multiple instances managed by the SNMP Agent.
   
   

5. If device is reachable from the gateway as well as device is also responding with SNMP but still unable to see the discovered devices.

   • Need to check the vprobe logs in the gateway. The vprobe logs is saved in /var/log/app/vprobe.log.

   • Issue the following command to check the ongoing discovery logs.

             tail -f /var/log/app/vprobe.log
             

   • Perform SNMP discovery again and observe the logs.

     logs analyzation:

     • SNMP started: Snmp4JSessionImpl#63: Snmp session intialized
     AbstractNetworkDiscovery#62: ************ Discovery scan started for profile 3008 ************
     • Device not reachable from gateway: NetworkDiscoveryResponseListenerImpl#114: Resource failed to discover V4:172.26.1.16, sourceNMAP
     • Device SNMP credential timeout: SnmpResourceDiscoveryImpl#82: Snmp time out : V4:172.26.1.14
     • Device discovery failed with SNMP: NetworkDiscoveryResponseListenerImpl#114: Resource failed to discover V4:172.26.1.14, sourceSNMP
     • Discovery is completed: Snmp4JSessionImpl#83: Snmp session disconnected.

   • If no conclusive information is found, consider enabling additional debug logs for a more detailed analysis.

6. How to enable more debug logs?

   • Connect to gcli

             vgprompt#gcli + enter
             

   • Enter following command

             gcli@gateway>nd log on <30 no of mins>
             

     Example: gcli@gateway>nd log on 30
     ntwrk.disc on A Timer with timeout 30min has created to revert the val to off
     snmp.disc on A Timer with timeout 30min has created to revert the val to off
     snmp.topology on A Timer with timeout 30min has created to revert the val to off
     disc.response on A Timer with timeout 30min has created to revert the val to off
     gcli@gateway>

   • Perform the discovery process again after executing the following command.

             tail -f /var/log/app/vprobe.log
             

• After the completion of the discovery process, analyze the vProbe logs as indicated in the previous comments.

  logs analyzation:

  • Device snmp timeout: com.vistara.gateway.plugin.discovery.error.snmp.SnmpTimeOutException: Snmp is not working with any credential for device :V4:172.26.1.14
  • Successfully discovered devices json files: AbstractDiscoveryResponseSerializer#39: Response is saved to /var/log/app/tmp/network-discovery-chunk-1559559930044.json
  Notes:
  • Upon discovery, devices will transmit their information to the cloud, and this data is logged in files. Kindly review the log files located in the /var/log/app/tmp/ directory for further details.
  • File name start from network-discovery-chunk-.json
  • To view the timestamps of the most recent files, execute the following commands:

  1. cd /var/log/app/tmp/ folder

  2. ll network-discovery-chunk-*.json

7. Discovered devices data is not matching with actual device data like device type,os,etc..

   • Improper/wrong device data can be possible in following case:

     • Check /var/log/app/tmp/network-discovery-chunk-<1559559930044>.json files whether device data is correct or not.
       

   • If the data is incompatible with the fields in SNMP device type definitions within the UI, the device data may become inconsistent. In such cases, navigate to the corresponding Management Profile, synchronize SNMP Device Type Definitions. This action will push the SNMP device type definitions back to the respective gateway. Subsequently, initiate a rescan of the SNMP Discovery Profile to ensure that the changes are reflected in the device.

8. How to capture SNMP packets on specific device?

   • Execute the following command at gateway and perform the discovery

     Command

             tcpdump -v -i any 'ip host <ip> && udp port <port>' -s 3000 -w /home/ruser/{filename}.pcap
             

   • To stop the above command press ‘ctrl + enter’

   • Above command can be used to check the device behavior while discovery is going on. As well as we can analyze the collected data.

   • You may read the tcpdump generated file with help of wireshark tool.