👀 Views: 19 💬 Answers: 1 📅 Created: 2025-06-05

nginx ubuntu firewall ufw bash

I've been banging my head against this for hours. After setting up a new Ubuntu 22.04 server with Nginx, I am working with persistent 502 Bad Gateway errors when trying to access my web application. The application runs on a separate backend service through a socket, and I've confirmed that it's functioning properly without any firewall rules applied. I initially set up UFW with the following commands: ```bash sudo ufw allow 'Nginx Full' sudo ufw allow 3000/tcp ``` I also ensured that my Nginx configuration points to the correct socket: ```nginx server { listen 80; server_name example.com; location / { proxy_pass http://unix:/path/to/your/socket.sock; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; } } ``` However, when I check the Nginx behavior logs, I see entries like this: ``` 2023/10/03 12:34:56 [behavior] 12345#0: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.1.1, server: example.com, request: "GET / HTTP/1.1", upstream: "http://unix:/path/to/your/socket.sock:", host: "example.com" ``` I have also tried disabling UFW using `sudo ufw disable` to see if it resolves the scenario, and the application works fine, indicating that the firewall configuration is likely the culprit. I’ve double-checked that the socket file has the right permissions (I set it to `660`), and the user running Nginx has access to it. Despite my efforts, I need to pinpoint what’s wrong with the UFW rules. Are there any specific configurations or rules I might be missing that would allow Nginx to connect to my backend service through the socket without throwing a 502 behavior? Any help would be greatly appreciated! I'm working on a API that needs to handle this. Is there a better approach?