DevOps & Cloud
Risk: Medium
Port 9090 — Prometheus Server Web UI & Metrics API
Port 9090 is the default web UI and PromQL querying interface for the Prometheus monitoring system.
PORT NUMBER
9090
PROTOCOL
TCP
DEFAULT PROCESS
prometheus
FIREWALL TARGET
9090/tcp
Instant Terminal Fixes for Port 9090
macOS & Linux Terminal
1. Check who is listening on port 9090:
curl -I http://localhost:9090/-/healthy2. Kill process occupying port 9090 (EADDRINUSE fix):
kill -9 $(lsof -t -i:9090)3. UFW Firewall Allow rule:
sudo ufw allow from 10.0.0.0/8 to any port 9090 proto tcpWindows PowerShell (Admin)
1. Check listening port:
Get-NetTCPConnection -LocalPort 90902. Force kill process on port 9090:
Stop-Process -Id (Get-NetTCPConnection -LocalPort 9090).OwningProcess -Force3. Docker Port Forwarding Mapping:
docker run -p 9090:9090 -d prom/prometheusCommon Error Encountered
Prometheus server startup failed: address already in use on port 9090
Security Advisory & Hardening
Prometheus does not include native authentication by default. Put it behind an authenticating reverse proxy or enable web configuration basic auth.
Frequently Asked Questions
Port 9090 Questions & Answers
Common questions regarding default services, kill commands, and firewall configurations.
Port 9090 is commonly used for Prometheus Server Web UI & Metrics API. Port 9090 is the default web UI and PromQL querying interface for the Prometheus monitoring system.