How to Change the SpectroSERVER's SNMP Engine ID So That It Conforms to RFC Standards

Products

• CA Spectrum
• DX NetOps

Issue/Introduction

The Spectrum installer will set the SpectroSERVER's SNMP Engine ID by default to the mac address of the
   machine. This ensures that the SNMP Engine ID will be unique, however, this does not fully conform to RFC
   standards. In most instances this will not be an issue. In some edge cases, it might be necessary to
   adjust the engine ID so that it conforms.

The SpectroSERVER's SNMP Engine ID is defined in the .vnmrc file

$SPECROOT/SS/.vnmrc
snmpv3_engine_id=1122334455

Environment

Release : 20.2.x, 21.2.x

Component : SpectroSERVER

Resolution

STEPS

1) Enterprise ID

We will use Computer Associates 791 Enterprise ID and convert this to hex padded with leading zeros.

  791 decimal --> 00000317 hex

 

2) Change the first bit to 8

Next, per RFC3411 change the leading bit to 8

 80000317

 

3) Specify that a mac address will be used

The next octet will be set to 03 to indicate what follows will be a mac address

80000317 + 03

4) Append the SpectroSERVER's mac address which will make the string unique

For security reasons we will use 001122334455 in this example

80000317 + 03 + 001122334455

 

5) Update the SpectroSERVER's .vnmrc configuration file with the new Engine ID

$SPECROOT/SS/.vnmrc
snmpv3_engine_id=8000031703001122334455



6)  Restart the SpectroSERVER


To Test, I sent an SNMP Inform to the SpectroSERVER without the engine ID and the SS responds with a report pdu

Additional Information

 

RFC3411
https://datatracker.ietf.org/doc/html/rfc3411#page-52

3) The length of the octet string varies.

                    The first four octets are set to the binary
                    equivalent of the agent's SNMP management
                    private enterprise number as assigned by the
                    Internet Assigned Numbers Authority (IANA).
                    For example, if Acme Networks has been assigned
                    { enterprises 696 }, the first four octets would
                    be assigned '000002b8'H.

                    The very first bit is set to 1. For example, the
                    above value for Acme Networks now changes to be
                    '800002b8'H.

                    The fifth octet indicates how the rest (6th and
                    following octets) are formatted. The values for
                    the fifth octet are:

                      0     - reserved, unused.

                      1     - IPv4 address (4 octets)
                              lowest non-special IP address

                      2     - IPv6 address (16 octets)
                              lowest non-special IP address

                      3     - MAC address (6 octets)
                              lowest IEEE MAC address, canonical
                              order

                      4     - Text, administratively assigned
                              Maximum remaining length 27

                      5     - Octets, administratively assigned
                              Maximum remaining length 27

                      6-127 - reserved, unused

                    128-255 - as defined by the enterprise
                              Maximum remaining length 27