Port 199
SMUX (SNMP Multiplexer)
**SMUX (SNMP Unix Multiplexer)** is a protocol running primarily on port 199 that facilitates the integration of sub-agents into the overall SNMP agent framework, enabling modular management in network devices and systems. It allows different components to provide their own management information autonomously while coordinating through a central SNMP master agent..
Technical Details
Overview
SMUX, short for SNMP Unix Multiplexer, was designed to extend the Simple Network Management Protocol (SNMP) framework by allowing multiple sub-agents to communicate with a master SNMP agent. This architecture enables modularity, as various network services or components can provide their own management data without relying on a monolithic agent implementation.
Protocol Details
SMUX operates over TCP and UDP on port 199. It uses an ASN.1-based encoding similar to SNMP and was primarily adopted in Unix-based systems. The sub-agents connect to the master agent via SMUX, register the MIB objects they manage, and handle requests that fall under their registered sections. This approach allows the master agent to delegate specific tasks dynamically.
Usage Scenarios
Commonly, SMUX was found in Cisco and other network vendors’ equipment as well as Unix servers requiring modular SNMP management. Although largely superseded by AgentX (RFC 2741), SMUX is still relevant in legacy systems where backward compatibility or minimal changes are preferred.