SNMP agent — device monitoring queries, UDP 161.
Routers, switches, printers, UPSes, and servers running an SNMP agent (commonly Net-SNMP's snmpd) listen on UDP 161 and answer GET/GETNEXT requests from monitoring systems. Net-SNMP's default agentaddress is UDP 161 on all IPv4 interfaces. It appears on scans anywhere network monitoring exists, often still configured with SNMPv1/v2c community strings that travel in cleartext. Traps go outbound to port 162, not here.
Do not expose
v1/v2c community strings are cleartext and readable device inventory; keep 161 on a management network and use SNMPv3 with auth and privacy.
$ snmpwalk -v2c -c public TARGET systemSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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