Monday, March 14, 2022

[SOLVED] Google Cloud Firewall: Port is blocked

Issue

I am trying to set up a simple web server in Google Cloud Platform on a Debian machine. When running a port scan (https://www.ipvoid.com/port-scan/) without any firewall rules, all ports are shown as filtered. When setting up a rule for port 80, the scan gives back that the port is blocked. Am I doing something wrong with the firewall settings?

This is what the config looks like.

Thanks in advance!


Solution

I re-built your issue on my Gcloud console, 80 port will be blocked if I don't select the firewall options as picture during creating an instance.

enter image description here

The firewall rule will auto set up if I select these firewall options. enter image description here

You also can verify your firewall settings in Debian, View the full list of application profiles by running:

$ sudo ufw app list

The WWW profiles are used to manage ports used by web servers:

Output

Available applications:
. . .
  WWW
  WWW Cache
  WWW Full
  WWW Secure
. . .

If you inspect the WWW Full profile, it shows that it enables traffic to ports 80 and 443:

$ sudo ufw app info "WWW Full"

Output

Profile: WWW Full
Title: Web Server (HTTP,HTTPS)
Description: Web Server (HTTP,HTTPS)

Ports:
  80,443/tcp

Allow incoming HTTP and HTTPS traffic for this profile:

$sudo ufw allow in "WWW Full"


Answered By - William
Answer Checked By - Dawn Plyler (WPSolving Volunteer)
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