TRAP forwarder, SNMPv2c to SNMPv3

In this configuration SNMP Proxy Forwarder receives SNMPv2c TRAP PDU and forwards it as SNMPv3 TRAP PDU.

Note

When forwarding SNMP notifications, server part receives TRAPs from SNMP agents, while client part forwards them towards Managers. This is opposite to SNMP commands forwarding where server parts is directed towards SNMP managers and client part talks to SNMP agents.

This means that if you want to forward both SNMP command and notification packets, you’d need to run at least two pairs of servers and clients forwarding packets in opposite directions.

You could test this configuration by running:

$ snmptrap -v2c -c public 127.0.0.1:1162 12345 1.3.6.1.2.5 sysDescr s myagent

Server configuration

Server is configured to:

  • listen on UDP socket at localhost
  • expect SNMP TRAP packets sent over SNMPv2c, community name “public”
  • forward all queries to snmpfwd client through an unencrypted trunk connection running in client mode
#
# SNMP TRAP forwarder: Manager part configuration
#

config-version: 2
program-name: snmpfwd-server

snmp-credentials-group {
  snmp-transport-domain: 1.3.6.1.6.1.1.100
  snmp-bind-address: 127.0.0.1:1162

  snmp-engine-id: 0x0102030405070809

  snmp-community-name: public
  snmp-security-name: public

  snmp-security-model: 2
  snmp-security-level: 1

  snmp-credentials-id: snmp-credentials
}

context-group {
  snmp-context-engine-id-pattern: .*?
  snmp-context-name-pattern: .*?

  snmp-context-id: any-context
}

content-group {
  snmp-pdu-type-pattern: (TRAPv1|TRAPv2)
  snmp-pdu-oid-prefix-pattern-list: .*?

  snmp-content-id: trap-content
}

peers-group {
  snmp-transport-domain: 1.3.6.1.6.1.1.100
  snmp-bind-address-pattern-list: .*?
  snmp-peer-address-pattern-list: .*?

  snmp-peer-id: 100
}

trunking-group {
  trunk-bind-address: 127.0.0.1
  trunk-peer-address: 127.0.0.1:30301
  trunk-ping-period: 60
  trunk-connection-mode: client

  trunk-id: trunk-1
}

routing-map {
  matching-snmp-credentials-id-list: snmp-credentials
  matching-snmp-context-id-list: any-context
  matching-snmp-content-id-list: trap-content
  matching-snmp-peer-id-list: 100

  using-trunk-id-list: trunk-1
}

Download server configuration file.

Client configuration

Client is configured to:

  • listen on server-mode unencrypted trunk connection
  • place inbound TRAP PDUs into SNMP v3 messages and forward them to public SNMP manager running at demo.snmplabs.com

Warning

Since SNMP TRAP is always a one-way communication, SNMPv3 parties can’t negotiate authoritative SNMP engine ID automatically which is used for authentication and encryption purposes.

When SNMPv3 authentication or encryption services are being used, snmp-engine-id of the client SNMP engine becomes the authoritative SNMP engine ID for the purpose of sending SNMPv3 TRAP. If the snmp-security-engine-id is configured, it overrides snmp-engine-id for the purpose of sending SNMP v3 notifications.

The USM user table at the receiving end must be configured to accept messages from snmp-engine-id or snmp-security-engine-id.

#
# SNMP TRAP forwarder: Agent part configuration
#

config-version: 2
program-name: snmpfwd-client

peers-group {
  # Our SNMP engine ID becomes authoritative for the purpose of
  # sending SNMPv3 TRAPs
  snmp-engine-id: 0x8000000001020304

  # SNMPv3 TRAP would pick up security-engine-id instead of snmp-engine-id
#  snmp-engine-id: 0x80000000FFFFFFFF
#  snmp-security-engine-id: 0x8000000001020304

  snmp-transport-domain: 1.3.6.1.6.1.1.1
  snmp-bind-address: 0.0.0.0:0

  # time out SNMP request in 1 second
  snmp-peer-timeout: 100
  snmp-peer-retries: 0

  snmp-security-model: 3
  snmp-security-level: 3

  snmp-security-name: usr-md5-des
  snmp-usm-user: usr-md5-des
  snmp-usm-auth-protocol: md5
  snmp-usm-auth-key: authkey1
  snmp-usm-priv-protocol: des
  snmp-usm-priv-key: privkey1

  snmp-peer-address: 104.236.166.95:162
  snmp-peer-id: snmplabs-v3
}

trunking-group {
  trunk-bind-address: 127.0.0.1:30301
  trunk-ping-period: 60
  trunk-connection-mode: server

  trunk-id: <discover>
}

original-snmp-peer-info-group {
  orig-snmp-bind-address-pattern: .*?
  orig-snmp-context-name-pattern: .*?

  orig-snmp-pdu-type-pattern: TRAPv2
  orig-snmp-oid-prefix-pattern: .*?

  orig-snmp-engine-id-pattern: .*?
  orig-snmp-context-engine-id-pattern: .*?

  orig-snmp-transport-domain-pattern: .*?
  orig-snmp-peer-address-pattern: .*?

  orig-snmp-security-level-pattern: .*?

  orig-snmp-security-name-pattern: .*?
  orig-snmp-security-model-pattern: .*?

  orig-snmp-peer-id: agent-1
}

server-classification-group {
  server-snmp-credentials-id-pattern: .*?
  server-snmp-context-id-pattern: .*?
  server-snmp-content-id-pattern: .*?
  server-snmp-peer-id-pattern: .*?

  server-classification-id: any-classification
}

routing-map {
  matching-trunk-id-list: trunk-1
  matching-orig-snmp-peer-id-list: agent-1
  matching-server-classification-id-list: any-classification

  using-snmp-peer-id-list: snmplabs-v3
}

Download client configuration file.