Port 161: SNMP
Monitoring and management of network devices. SNMP with the default community string "public" leaks device details and is used for amplification. Never expose it to the internet.
- Free
- No Sign-Up
- Runs in Your Browser
Port Lookup
Port 161 at a glance
Port161
ProtocolUDP
ServiceSNMP
Open to the Internet?No, keep it on a private network
See What Is Listeningss -lntup | grep ':161 '
Test From Outsidenmap -sU -p 161 your-server
Block with UFWufw deny 161/udp
Block with nftablesnft add rule inet filter input udp dport 161 drop
SNMP uses UDP port 161. Monitoring and management of network devices.
SNMP with the default community string "public" leaks device details and is used for amplification. Never expose it to the internet.
If ss shows something listening on port 161 on a public address, bind it to 127.0.0.1 or a private interface in the service's own configuration, and drop the port in the firewall as well.
Other Ports
20 FTP Data21 FTP22 SSH23 Telnet25 SMTP53 DNS67 DHCP Server80 HTTP110 POP3123 NTP143 IMAP161 SNMP389 LDAP443 HTTPS445 SMB465 SMTPS514 Syslog587 Mail Submission853 DNS over TLS993 IMAPS995 POP3S1194 OpenVPN1433 Microsoft SQL Server1900 SSDP / UPnP2049 NFS2083 cPanel (SSL)2087 WHM (SSL)3306 MySQL / MariaDB3389 RDP3478 STUN / TURN5060 SIP5432 PostgreSQL5900 VNC6379 Redis8006 Proxmox VE8080 HTTP Alternate8443 HTTPS Alternate11211 Memcached25565 Minecraft27017 MongoDB51820 WireGuard
Questions
What is port 161 used for?
SNMP. Monitoring and management of network devices.
Is it safe to open port 161?
No, keep it on a private network. SNMP with the default community string "public" leaks device details and is used for amplification. Never expose it to the internet.
How do I check if port 161 is open?
On the server, ss -lntup | grep ':161 ' shows what is listening. From another machine, nmap -sU -p 161 your-server shows whether the firewall lets it through.
How do I block port 161?
With UFW: ufw deny 161/udp. With nftables, add a drop rule for dport 161 in your input chain.
Free Tools
More tools
Port LookupWhat runs on a TCP or UDP port, and whether it should be open.Firewall Rule GeneratorGenerate iptables, nftables and UFW rules for common server set-ups.What Is My IPYour public IP address, reverse DNS, network and ASN.IP Reputation CheckerCheck an IP against spam blocklists and threat feeds at once.
Abuse from open ports on your VMs?
Frabs spots amplification, scans and floods leaving any VM and stops them, without touching your firewall.