Which SNMP library offers an API to get single properties of captured (tcpdump) SNMP packets like the request-ID or the protocol version?
I found that pySNMP offers such a low-level API but only for v1/v2c versions. But I need both v2c and v3.
what exactly you want to know.  whether :
 python net-snmp api supports v3 or not 
or
oid for finding request-id of a snmp packet
How to get the request ID of a SNMP packet in Python