Re: [lwip-devel] Missing things for SNMPv3

[Marco Veeneman]

Hello Dirk,

Thank you for your answer. I will see if i can continue on this.

I gave the SNMPv3 agent a try and for me it's only working partially.

The following options from Net-SNMP are working correct: noAuthNoPriv and authNoPriv, but authPriv it is not always giving me a response.

Stepping trough the code resulted in entering the following code branch in snmpv3_crypt, called from snmp_complete_outbound_frame():

    /* RFC 3414 mandates padding for DES */
    if ((length & 0x07) != 0) {
      return ERR_ARG;
    }

So, for some reason the padding is not correct when generating a response.

Marco

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Van: lwip-devel <lwip-devel-bounces+address@hidden> namens Dirk Ziegelmeier <address@hidden>
Verzonden: woensdag 17 augustus 2016 13:03
Aan: lwip-devel
Onderwerp: Re: [lwip-devel] Missing things for SNMPv3

 

Hello Marco,

the work was initially started by Elias Önal. Unfortunately, I never heard of him again.

The current state is that encryption and authentication do work. The agent implements the User-based security model, RFC 3414.

What is missing (what I currently remember, there may be more when carefully reading the RFC) is the implementation of the USM MIB and support for engine time sync (snmpEngineTime) when a client initially contacts the agent. I'd guess an experienced developer would need less than one week to implement this.

Don't forget the work involved on the application layer, NV storage for snmpEngineBoots and user/password management.

Dirk

--
Dirk Ziegelmeier * address@hidden * http://www.ziegelmeier.net

On Wed, Aug 17, 2016 at 11:10 AM, Marco Veeneman <address@hidden> wrote:

Hi,

First of all, thank you Dirk for applying a modified version of patch #9044: SNMP response for failed get operation.

I'm currently working on an SNMP enabled device and I was wondering what is missing in SNMP to make the SNMP agent in LwIP SNMPv3 compliant.

I see there already is a reference implementation for mbedTLS. I try to figure out how much effort it would take to get the SNMPv3 agent ready to release in the field.

Marco

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