[erlang-questions] SNMP usm discovery

[Dominik Pawlak]

I'm trying to find a way to perform a snmpEngineID discovery process as defined in RFC3414 chapter 4 in a manager.

The process is pretty simple: you send a v3, usm Request message
    with security level: noAuthNoPriv, empty user name, endineID and
    varbinds. The agent then sends a report containing his engineID.

I tried registering agent with empty or no security name defined,
    but when I try to send the Request message I get:
snmpm:register_agent("u", "a",
[{engine_id,[]},{address,[x,x,x,x]},{version,v3},{sec_model,usm},{sec_name,""},{sec_level,noAuthNoPriv}]).
snmpm:sync_get("u", "a", "auth", [], 1000).

{error,{send_failed,1440625960,unknownSecurityName}}
=ERROR REPORT==== 20-May-2014::11:12:57 ===
[ snmp : manager : snmpm_mpd : <0.55.0> ] 
MPD: CONFIG ERROR: unknownSecurityName (message: {message,'version-3',
                                                  {v3_hdr,996332938,484,
                                                   [4],
                                                   3,undefined,undefined},
                                                  [48,24,4,0,4,4,97,117,116,
                                                   104,160,14,2,4,85,222,53,
                                                   40,2,1,0,2,1,0,48,0]})

I also tried registering a usm user with an empty (one space) name:
snmpm:register_usm_user(" ", " ", [{sec_name, "initial"}]).
snmpm:register_agent("u", "a", [{engine_id, "
"},{address,[x,x,x,x]},{version,v3},{sec_model,usm},{sec_name,"initial"},{sec_level,noAuthNoPriv}]).

This time the message is sent, and the agent does respond with a
    message containing his engineID, but this information is not
    provided to the snmpm_user module:

=INFO REPORT==== 20-May-2014::12:21:45 ===
SNMPM default user callback received handle_error:
   ReqId:    -1
   Reason:   {failed_processing_message,
                 {securityError,usmStatsUnknownEngineIDs}}
   UserData: undefined
{error,{timeout,1440625963}}

What is the proper way of doing this?

-- 
Cheers,
Dominik Pawlak
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