[AGENT++] snmpv3 - question on usm use of engine_id , time window

[Anurag Jain]

1 .Our system currently (a single v3 manager daemon process )manages snmpv3 communication to multiple snmp v3 devices concurrently where each agent may or may not have a unique security user profile

For this purpose we also cache the snmpv3 security user information and using the USM::add_usm_user function adding
users as on need basis per engineID using 

  int add_usm_user(const OctetStr& user_name,
           const OctetStr& security_name,
           const long int  auth_protocol,
           const long int  priv_protocol,
           const OctetStr& auth_password,
           const OctetStr& priv_password,
           const OctetStr& engine_id);

For the above purpose we extract the engine_id by calling function v3MP::get_from_engine_id_table  , in case this function
does not return success we call the second version of add_usm_user which does not require engine_id.

Is the above fallback recommended and is this approach to adding users with and without engine_id as a fallback recommended , if not 
when should the function without engine_id  be used and safely too ?  Could the use of add_usm_user without engine_id create problems with key localization across multiple agents with same security profile ?

2. On another note we have another scenario where the the agent to which successful communication was established and worked fine until 
a reboot of the agent occasionally throws the time window out of sync causing communication failure , in this case how can the v3 manager resync and/or with regards time- window checking /timeliness checks ?

Can the v3 function USM::remove_time_information be used for resetting internal time related state and thereby forcing a resync ?


Help and comments most appreciated .

Thanks
Anurag
 		 	   		  
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