snmpv3 authPriv issue

[spapantoniou85]

Hello to all,

I have been working in the last period to integrate a series of UPS of APC using the snmp protocol.

The version required is v3. 

I have used this site: http://luasnmp.luaforge.net/objects.html to get information for the parameters of snmp.

Code:

ups1, err = snmp.open{
    version = snmp.SNMPv3,
  community = "public",
  port = 161,
  peer = "IP address",
  user = "Sotirios",
  authPassphrase = "Papantoniou1",
  privPassphrase  = "Papantoniou2",
  authType = "MD5",
  privType = "AES",
  timeout = 2,
  securityLevel = "authNoPriv",--"noAuthNoPriv",
  }
assert(ups1, err)
log(ups1)
log(err)

local OID_NAS3 = {
    {'Varname',"1.3.6.1.4.1.935.1.1.1.1.1.1.0"},--NEW
}

  for _, item in ipairs(OID_NAS3) do
    vbind, err = ups1:get(item[2])
    if vbind then
    log(vbind.value)
    else
      log('error reading from snmp: ' .. tostring(err))
      --grp.checkwrite('EL_UPS_communication_KO',true)
     
    end
  end

On security level when I am using noAuthNoPriv or authNoPriv everything is working correctly. When I use authPriv adding all the parameters correctly (cross-checked with other 3rd party software) I have problem with the communication. 

The log message I got was:

Code:

error reading from snmp: snmp: internal error - synch request id is 0

This error arrives even when the parameters I have inserted are wrong. Google searching:"synch request id is 0"  I have found the error on the source code but no explanation why this is happening.https://github.com/hleuwer/luasnmp/blob/.../nm_snmp.c

Has anybody else found a similar problem? How can I solve this issue?

Thank you

Sotiris