XDEGUG intercepting requests from any and all IP's, local or remote

[OPSCarlos]

XDEGUG intercepting requests from any and all IP's, local or remote, when debugging with VSCODE through Remote-SSH.

It does not matter how I configure php.ini in the server or Xdebug launch.json on my local machine, if I listen for Xdebug in VSCODE and then launch a web browser pointed to my site, XDebug will intercept and pause no matter which IP address I am launching the website from. It can be from a machine in my local network where my VSCODE machine sits or a machine anywhere outside my local network (remote location).

My expectation, based on the configuration, is that only web requests launched from my local network would be intercepted; even only web requests from my VSCODE machine!

Software Versions:

Distributor ID: Ubuntu
Description: Ubuntu 22.04.5 LTS
Release: 22.04
Codename: jammy

XDebug Version: 3.4.2

Server php.ini Configuration:

`
zend_extension=xdebug.so

xdebug.mode = debug

xdebug.discover_client_host = 1

xdebug.log = "/var/log/xdebug.log"

xdebug.log_level=1

xdebug.start_with_request = yes
`

Local Workstation Software:

Edition: Windows 11 Home
Version: 24H2
OS build:26100.3624

VSCODE Related Software:

VSCODE Version 1.99.1
Remote - SSH Version 0.119.0
PHP Debug (XDebug) version 1.35.0

VSCODE XDebug JSON Configuration:

`
"version": "0.2.0",
"configurations": [

    {
        "name": "Listen for Xdebug",
        "type": "php",
        "request": "launch",
        "port": 9003
    }

`
I have tried changing the server php.ini configuration with one of the following instead of xdebug.discover_client_host = 1:

• xdebug.client_host = 127.0.0.1
• xdebug.client_host = localhost
• xdebug.client_host=1

I am not an expert by any means so any guidance to properly configure would be greatly appretiated. Thanks in advance
Carlos

[zobo]

Hello @OPSCarlos

There are two concepts here that need to be configured correctly:

1. where does Xdebug connect to
   This is controlled by either xdebug.client_host or xdebug.discover_client_host. Since you are using VSCode Remote and there is no mention of Docker, I suggest you use xdebug.client_host = 127.0.0.1 and remove xdebug.start_with_request = yes.

2. when does Xdebug connect to the IDE
   xdebug.start_with_request = yes tells Xdebug to try to connect to the IDE on every request. I suggest you remove this and use a Xdebug helper browser extension. See Activating Step Debugger in the official documentation.

I just want to emphasize that leaving Xdebug configured like you have now on a public server - even worse if production - is a security risk, since anyone can get Xdebug to connect back to them. Besides setting a fixed xdebug.client_host you can also set xdebug.trigger_value that will add a "secret" component. If the debugger was exposed, I urge you to review the logs and see if there were any unknown successful Xdebug connections in the past.

[OPSCarlos]

Hi @zobo

First of, thank you for responding to my inquiry. Perhaps I should have started a treat in Stackoverflow instead of here, realizing now is not a bug but my lack of knowledge.

Anyways, I followed your configuration recomendations of setting xdebug.client_host = 127.0.0.1, removing xdebug.start_with_request = yes and installing Xdebug Helper by JetBrains in my browser. I can indeed connect and debug in VSCODE. Thank you.

My question is would this setup be secure then? Meaning only those with access to the server connection through VSCODE would be able to debug?

I notice, if I accees the site I want to debug from a browser outside the IDE environment I still get connection messages in the Xdebug log:
`
[28667] [Config] INFO: Trigger value for 'XDEBUG_TRIGGER' not found, falling back to 'XDEBUG_SESSION'

[28667] [Config] INFO: Trigger value for 'XDEBUG_SESSION' not found, so not activating

`

Again, thanks for taking time to help me.

[zobo]

No problem, I try to answer all questions. I tend to look at Stack Overflow too, but less frequently. Great to see you got it working.

So first, the setup is (more) secure then before. Since client_host points to 127.0.0.1 Xdebug will not connect to any other address. This means that an outside attacked will not be contacted by Xdebug as a consequence of them opening the page. Even if the attacker would have the XDEBUG_TRIGGER cookie/parameter set.

The second part of the question, yes, Xdebug is active and is checking - on every request - if the trigger cookie/parameter is present and if it should connect to the IDE. You probably see there log entries because you have your xdebug,log_level set to some higher than default value.

Now the disclaimer again. If this is a production server, you should not load Xdebug. Do your development on a separate server/environment. Maybe use docker/devcontainers.