TUN mode not working on Linux while proxy mode functions properly

[daniyal-abbassi]

When attempting to use TUN mode on Linux, the connection fails with an error:

``configure tun interface: operation not permitted``

The UI shows:

Loading → Pinging → Switching to another ping

A popup appears:

    [Proxy] Your OS or desktop environment (linux-unknown) isn't supported for automatic proxy disabling. You'll need to disable the proxy manually.

The connection stays in "loading" forever and eventually fails.

Proxy mode works fine, but TUN mode fails on all servers.
Steps to Reproduce:

Launch ProxyCloud GUI on Linux.

Switch to TUN mode.

Select any server → Attempt to connect.

Observe the "operation not permitted" error in logs.

log :

08/16/2025, 20:29:07 --info--> Vibe Output:  
FATAL CORE initialize inbound/tun[tun-in]: configure tun interface: operation not permitted  
INFO CORE STOPPED: UNEXPECTED_ERROR initialize inbound/tun[tun-in]: configure tun interface: operation not permitted  
INFO CORE STOPPED: START_SERVICE initialize inbound/tun[tun-in]: configure tun interface: operation not permitted  

08/16/2025, 20:29:07 --info--> Vibe Output: Waiting for CTRL+C to stop  

08/16/2025, 20:29:47 --info--> TESTING...  

08/16/2025, 20:30:05 --info--> Vibe manual connection failed after timeout.  

08/16/2025, 20:30:05 --info--> [Connection] Disconnecting from: vibe...  

08/16/2025, 20:30:05 --info--> Failed to connect to vibe.  

08/16/2025, 20:30:05 --info--> Killing vibe-core...

Environment:

OS: Ubuntu 22.04.5 LTS - 64-bit - GNOME 42.9 - WINDOWING STSTEM X11

Installation method: AppImage

Run as root? no

[code3-dev]

Thank you for using ProxyCloud GUI and for reporting this issue 🙏

The error happens because creating and configuring a TUN interface on Linux requires root privileges. Since the logs show operation not permitted and the app was not run as root, TUN mode cannot be initialized.

Please try running the application with administrator (root) privileges, for example:

sudo ./proxycloud-gui-linux-x86_64.AppImage

or if installed:

sudo proxycloud-gui

This should allow the TUN interface to be created properly.

[daniyal-abbassi]

Follow-up on Root Privileges Issue – Workaround

Thank you for your response! I tested running ProxyCloud GUI with sudo as suggested, but encountered new issues due to Linux security restrictions. Here’s what happened and how I resolved it:

Problem When Using sudo

1.Electron Sandbox Block

[FATAL] Running as root without --no-sandbox is not supported.

2.X11/DBus Permission Errors

Authorization required, but no authorization protocol specified  
Could not open the default X display

Workaround - (with AI)

To bypass these restrictions temporarily:

xhost +SI:localuser:root           # Allow root to use my display  
sudo -E proxycloud-gui --no-sandbox # Run with preserved env + sandbox disabled  
xhost -SI:localuser:root           # Revoke access afterward (security!) 

and finally TUN mode is working. I hope this solution helps others facing the same issue.
thank you for this GREAT app. A lot.

[code3-dev]

Thank you so much for the detailed follow-up and for sharing your workaround 🙏

You are absolutely right — running Electron apps as root triggers sandbox and display permission issues on Linux.
Your solution using xhost and --no-sandbox is very helpful, and we’ll make sure to document this so other users can benefit as well.

It’s great to hear that TUN mode is now working for you! 🚀

We truly appreciate your effort, feedback, and support for ProxyCloud GUI.