Port 161 — SNMP
Quick reference for TCP/UDP port 161, used by SNMP. Includes what the service does, security guidance and related ports.
What is port 161?
Simple Network Management Protocol — common on routers and switches.
What port does SNMP use?
SNMP listens on port 161 by default.
Is port 161 open? How to check
Run one of these from your computer, replacing HOST with the IP address or domain you want to test.
nc -zvu HOST 161
Test-NetConnection HOST -Port 161
nmap -sU -p 161 HOST
A refused or timed-out connection means the port is closed or filtered by a firewall.
Security guidance
High risk — do not expose to the internet
Port 161 (SNMP) is high-risk because the service it carries is a frequent target for credential attacks, brute force or unpatched-vulnerability scanning. Keep it bound to localhost or your VPN, never forward it directly on a router, and require strong authentication.
Related ports
Frequently asked
What is port 161 used for?+
Port 161 is the standard TCP/UDP port for SNMP. Simple Network Management Protocol — common on routers and switches.
What port does SNMP use?+
SNMP listens on port 161 by default.
Your IP Address Is Exposed Right Now
Every website you visit can see your real IP address and location. NordVPN encrypts your traffic and hides your identity with military-grade encryption. Stay anonymous online.