Trap Configuration¶

A trap service is a simple server that can handle SNMP traps sent by SNMP devices, such as routers or switches.

Trap configuration file¶

The trap configuration is kept in the values.yaml file in section traps. values.yaml is used during the installation process for configuring Kubernetes values.

See the following trap example configuration:

traps:
  communities:
    1:
      - public 
    2c:
      - public
      - homelab
  usernameSecrets:
    - secretv3
    - sc4snmp-homesecure-sha-des

  # Overrides the image tag whose default is the chart appVersion.
  logLevel: "WARN"
  # replicas: Number of replicas for trap container should be 2x number of nodes
  replicas: 2
  #loadBalancerIP: The IP address in the metallb pool
  loadBalancerIP: 10.202.4.202
  resources: 
    limits:
      cpu: 500m
      memory: 512Mi
    requests:
      cpu: 200m
      memory: 256Mi

Define communities¶

communities defines a version of an SNMP protocol and an SNMP community string, which should be used. The communities key is split by protocol version, with 1 and 2c as supported values. Under the version section, you can define the SNMP community string.

See the following example:

traps:
  communities:
    1:
      - public 
    2c:
      - public
      - homelab

Configure user secrets for SNMPv3¶

The usernameSecrets key in the traps section defines the SNMPv3 secrets for the trap messages sent by the SNMP device. usernameSecrets defines which secrets in “Secret” objects in k8s should be used, as a value it needs the name of “Secret” objects. For more information on how to define the “Secret” object for SNMPv3, see SNMPv3 Configuration.

See the following example:

traps:
    usernameSecrets:
      - sc4snmp-homesecure-sha-aes
      - sc4snmp-homesecure-sha-des

Define security engines ID for SNMPv3¶

SNMPv3 TRAPs require the configuration SNMP Engine ID of the TRAP sending application for the USM users table of the TRAP receiving application for each USM user. The SNMP Engine ID is usually unique for the device, and the SC4SNMP as a trap receiver has to be aware of which security engine IDs to accept. Define all of them under traps.securityEngineId in values.yaml.

By default, it is set to a one-element list: [80003a8c04], for example:

traps:
    securityEngineId: 
      - "80003a8c04"

The security engine ID is a substitute of the -e variable in snmptrap. The following is an example of an SNMPv3 trap:

snmptrap -v3 -e 80003a8c04 -l authPriv -u snmp-poller -a SHA -A PASSWORD1 -x AES -X PASSWORD1 10.202.13.233 '' 1.3.6.1.2.1.2.2.1.1.1

Define external gateway for traps¶

If you use SC4SNMP on a single machine, configure loadBalancerIP. loadBalancerIP is the IP address in the metallb pool. See the following example:

traps:
  loadBalancerIP: 10.202.4.202

If you want to use the SC4SNMP trap receiver in K8S cluster, configure NodePort instead. Use the following configuration:

traps:
  service: 
    type: NodePort
    externalTrafficPolicy: Cluster
    nodePort: 30000

Using this method, the SNMP trap will always be forwarded to one of the trap receiver pods listening on port 30000 (like in the example above, you can configure to any other port). So, it doesn’t matter that IP address of which node you use. Adding nodePort will make it end up in the correct place everytime.

A good practice is to create an IP floating address/Anycast pointing to the healthy nodes, so the traffic is forwarded in case of the failover. To do this, create an external LoadBalancer that balances the traffic between nodes.

Define number of traps server replica¶

replicaCount defines that the number of replicas per trap container should be 2 times the number of nodes.

traps:
  #For production deployments the value should be at least 2x the number of nodes
  # Minimum 2 for a single node
  # Minimum 6 for multi-node HA
  replicaCount: 2

Define log level¶

The log level for trap can be set by changing the value for the logLevel key. The allowed values areDEBUG, INFO, WARNING, or ERROR. The default value is WARNING.

Define annotations¶

In case you need to append some annotations to the trap service, you can do so by setting traps.service.annotations, for example:

traps:
  service:
    annotations:
      annotation_key: annotation_value

Aggregate traps¶

In case you want to see traps events collected as one event inside Splunk, you can enable it by setting traps.aggregateTrapsEvents, for example:

traps:
  aggregateTrapsEvents: "true"

Updating trap configuration¶

If you need to update part of the traps configuration, you can do it by editing the values.yaml and then running the following command to restart the pod deployment:

microk8s kubectl rollout restart deployment snmp-splunk-connect-for-snmp-trap -n sc4snmp

NOTE: The name of the deployment can differ based on the helm installation name. This can be checked with the following command:

microk8s kubectl get deployments -n sc4snmp