TUN Mode Overview
TUN mode is an advanced proxy feature in ClashX that captures system-level network traffic by creating a virtual network interface. Compared to traditional system proxy mode, TUN mode can proxy more types of applications.
TUN mode has multiple significant advantages:
TUN mode requires macOS 10.15 or higher. Some older systems may have compatibility issues.
Common Error Types
Error 1: Permission Denied
This is the most common reason for TUN mode startup failure. Error messages typically display as:
Typical Error Messages
"Failed to start TUN: Permission denied"
"Cannot create TUN device: Permission denied"
Root Cause Analysis:TUN mode requires administrator privileges to create virtual network interfaces and modify system routing tables.
Quick Diagnosis
First perform these basic checks:
"Address already in use" or "Port xxxx is already in use"
Error 3: Network Driver Conflict
Network drivers from some VPN or security software may conflict with ClashX's TUN interface.
- Other VPN applications (e.g., OpenVPN, WireGuard)
- Network monitoring tools (e.g., Little Snitch, Lulu)
- Virtualization software (VMware, Parallels)
- Network protection features of antivirus software
Permission Issues
Grant Administrator Permissions
TUN mode requires administrator privileges. If you see permission errors:
- Completely quit ClashX (right-click menu bar icon > Quit)
- Open "Applications" folder and find ClashX
- Right-click ClashX.app > Get Info
- Click the lock icon at bottom left and enter administrator password
- In "Sharing & Permissions", ensure your user account has "Read & Write" permissions
- Restart ClashX
Using Terminal to Grant Permissions
Alternatively, use Terminal commands:
Terminal Commands
sudo chown -R $(whoami):admin /Applications/ClashX.appsudo chmod -R 755 /Applications/ClashX.appIn macOS Monterey and later, the system will show a permission request dialog when first enabling TUN mode. Be sure to click "Allow".
System Security Settings
This command will add ClashX to allowed applications list.
- Restart Mac and hold Command + R to enter Recovery Mode
- Open "Utilities" > "Terminal"
- Enter
csrutil statusto check SIP status - If SIP is too restrictive, consider adjusting related settings (proceed with caution)
After modifying permissions, you must completely restart ClashX for changes to take effect. Use Command+Q or menu → Quit.
System Conflict Resolution
Identify Port Conflicts
Use the following commands to check port occupancy:
Check Port Usage
sudo lsof -i :53sudo lsof -i :7890sudo lsof -i :7891Use Terminal to check if TUN interface was created successfully:
| Solution | Difficulty | Recommendation |
|---|---|---|
| Modify ClashX port configuration | Easy | ⭐⭐⭐⭐⭐ |
| Stop the app occupying the port | Medium | ⭐⭐⭐⭐ |
| Force terminate conflicting process | Medium | ⭐⭐⭐ |
Check Network Interfaces
If utun device appears in the output, TUN interface was created successfully.
- Don't run multiple VPNs simultaneously: This will cause routing table confusion
- Priority Settings: Ensure ClashX network interface has highest priority
- Consider Alternatives: Use ClashX Enhanced Mode instead of TUN mode
DNS Configuration
TUN mode requires proper DNS configuration:
Go to "System Preferences" > "Security & Privacy" > "Firewall" > "Firewall Options", ensure ClashX is allowed to accept incoming connections.
Advanced Troubleshooting
View System Logs
ClashX detailed logs can help diagnose the root cause of problems:
- Click ClashX menu icon > Help > Show Logs
- Look for lines containing "TUN" or "error"
- Record error codes and timestamps
Reset Network Configuration
If the problem persists, try resetting ClashX network configuration:
Reset Steps
- Quit ClashX
- Delete configuration file:
~/.config/clash/ - Restart ClashX and import configuration
Update ClashX Version
Older versions of ClashX may have known TUN mode bugs:
- Visit GitHub Releases page to check latest version
- Check changelog for TUN-related fixes
- Download and install latest version
Before updating, it is recommended to backup your configuration files and custom rules to avoid data loss.
macOS System Update Impact
Some macOS system updates may affect how network extensions work:
| macOS Version | TUN Compatibility | Notes |
|---|---|---|
| macOS 15 Sequoia | Excellent | Requires latest version of ClashX |
| macOS 14 Sonoma | Good | Fully supported |
| macOS 13 Ventura | Good | Stable support |
| macOS 12 Monterey | Fair | Requires additional permission configuration |
Field Diagnostic Case: TUN Stuck on "Connecting"
The details below come from a real troubleshooting session on macOS 14.2 recorded on January 12, 2026. Compare them with your own system state as you work through the checks:
| Diagnostic Step | Command / Action | Expected Result |
|---|---|---|
| Check Network Extension | log show --predicate 'process == "ClashX"' --last 30m | grep -i tun |
The log should return TUN interface created. If you see a posix_spawn error, ClashX still lacks the required permissions. |
| Verify the virtual interface | ifconfig utun0 |
The interface should exist and include IPv4/IPv6 addresses. If you get interface not found, macOS never created the TUN adapter. |
| Check for DNS conflicts | scutil --dns | grep 'nameserver \\[0\\]' |
The nameserver should point to ClashX's built-in 198.18.0.1. If it still shows your ISP resolver, system traffic has not been taken over. |
| Run a speed verification | networkQuality -v |
After the fix, uplink/downlink latency should recover to roughly 60 ms / 20 ms, showing that traffic is flowing through the proxy path again. |
If any step fails, save the command output together with the ClashX log and attach a snippet from ~/Library/Logs/com.west2online.ClashX.log when opening a GitHub issue so the developers can reproduce the problem faster.
Prevention Measures and Best Practices
Correct Startup Sequence
If TUN mode cannot be enabled, try Enhanced Mode:
System Proxy Mode
Traditional system proxy mode is also effective:
- Weekly subscription updates: Keep node configuration up-to-date
- Monthly update checks: Upgrade ClashX version timely
- Clean log files: Avoid excessive disk space usage
- Backup configuration files: Prevent accidental data loss
Complete Reset
If all else fails, try complete reset:
Enhanced Mode: Similar functionality to TUN but better compatibility
System Proxy Mode: Works for most daily scenarios
Rule Mode + Manual Configuration: Set proxy for specific apps
Seek Help
Still can't solve the problem? Try these resources:
- GitHub Issues: Submit detailed error reports
- Community Forum: Exchange experiences with other users
- Telegram Group: Get real-time technical support
- Official Documentation: Consult latest troubleshooting guides
Summary
TUN mode is powerful but relatively complex. Most issues are related to permission configuration, port conflicts, or software conflicts. Follow this guide step by step and you should be able to enable TUN mode successfully. Remember, the community is always ready to help if you encounter difficulties!
