Monitoring

SNMP

Also called Simple Network Management Protocol, snmpget, snmpwalk, community string, SNMPv3, agent

A protocol for reading counters and settings from network devices, on UDP port 161.

A management station asks an agent on each device for values by OID: get one, or walk a whole subtree. v1 and v2c authenticate with a community string sent in the clear; v3 has users, signed messages (authNoPriv) and encrypted ones (authPriv). Counters only grow: a rate is the difference of two readings over the time between them, using the 64-bit ifHC… counters on fast links.

See it on real machines

Learn it on real machines.