# WHATPORT(161)

## NAME

port 161 — SNMP — SNMP agent — device monitoring queries, UDP 161.

Protocol: UDP  
IANA registry

## DESCRIPTION

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.

## EXPOSURE

**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.

## CHECK

```sh
snmpwalk -v2c -c public TARGET system
```

## SEE ALSO

- spec — [RFC 3411 — Architecture for SNMP Management Frameworks (STD 62)](https://datatracker.ietf.org/doc/html/rfc3411) (datatracker.ietf.org)
- source — [Net-SNMP (GitHub)](https://github.com/net-snmp/net-snmp) (github.com)
- docs — [snmpd.conf manual page](https://www.net-snmp.org/docs/man/snmpd.conf.html) (net-snmp.org)
- iana — [IANA Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) (iana.org)

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HTML: <https://whatport.net/161/> · JSON: <https://whatport.net/161.json> · full dataset: <https://whatport.net/ports.json>