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Port 9411 (Zipkin)

Zipkin tracing API and UI.

Registered (user) port, 1024-49151 TCP Monitoring and logging Do not expose to the internet

What port 9411 is used for

Zipkin tracing API and UI.

Security: should port 9411 be open?

Do not expose to the internet. Traces contain URLs, headers and sometimes tokens; keep internal.

IANA assignment

Port 9411 is in the registered range and has no IANA assignment. The usage above is unofficial but widespread.

Check what is listening on port 9411

Linux: is anything listening on TCP 9411?
sudo ss -tlnp 'sport = :9411'
Linux / macOS: which process owns the port
sudo lsof -nP -i :9411
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':9411 '
Windows (Command Prompt)
netstat -ano | findstr :9411
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 9411 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 9411
From Windows
Test-NetConnection HOST -Port 9411

Block port 9411 in the firewall

ufw
sudo ufw deny 9411/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 9411 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 9411 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 9411' -Direction Inbound -Protocol TCP -LocalPort 9411 -Action Block

Related ports

16686Jaeger UI4317OpenTelemetry OTLP gRPC4318OpenTelemetry OTLP HTTP9401sec-t4net-clt9402sec-pc2fax-srv9418Git protocol9443HTTPS alternate / Portainer9444wso2esb-console

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.