A few questions about SNMP. How to find out the number of ports?

Question

SNMP

There are several questions regarding the operation of snmp:
1) How to find out the number of ports? * if possible, then a specific command
2) If we consider pdu snmp, how much each part of it weighs (error status, id request, etc.)
3) If we again consider the snmp structure, then there is the last item "associated values" - what is located in it ?
Thank you for your attention!

Answer 1

1. There is such a command in Linux:
   

   [[email protected]~]# snmpwalk -v 2c -c public 172.19.250.32 .1.3.6.1.2.1.2.1.0
   IF-MIB::ifNumber.0 = INTEGER: 50
   [[email protected]~]# snmpwalk -v 2c -c public 172.19.250.32 IF-MIB::ifNumber
   IF-MIB::ifNumber.0 = INTEGER: 50

   
   by keys:
   To understand how snmp works, I recommend reading this
   UPD:
   Okay, I will also answer about the size of the
   PDU Type - 4 bytes
   Request ID - 4 bytes
   Error Status - 4 bytes
   Error Index - 4 bytes
   Variable Bindings - not defined