Title
VNC connection to macOS Screen Sharing fails after selecting Apple security type 30
Platform
Website - Chrome
Server Installation Method
Proxmox (Community Scripts)
Version
2.5.1
Troubleshooting
The Problem
Description
Termix is unable to establish a VNC connection to a Mac running the built-in macOS Screen Sharing service.
The connection reaches the Mac successfully, and the Mac advertises several supported VNC security types, including standard VNC authentication (type 2). However, the Guacamole VNC client automatically selects Apple authentication (type 30) and the client process exits immediately afterward.
Termix remains stuck on:
Connecting to VNC session...
or eventually reports:
Connection failed
Aborted. See logs.
Environment
- Termix: 2.5.1
- guacd: 1.6.0
- OS: Debian 13 / Proxmox LXC
- libvncclient1: 0.9.15+dfsg-1+deb13u2
- libgcrypt20: 1.11.0-7+deb13u1
- Target: macOS Mac mini using the built-in Screen Sharing service
- VNC port: 5900
macOS configuration
The following settings are enabled:
System Settings → General → Sharing → Screen SharingAllow access for: All usersVNC viewers may control screen with password
Remote Management is disabled.
The issue occurs both:
- with the macOS account username and password
- with the separate VNC password and no username
Network connectivity
The VNC server is reachable from the Termix host:
$ nc -vz 10.0.0.11 5900
M-Mac-mini.****se [10.0.0.11] 5900 (?) open
Relevant guacd log
With debug logging enabled:
VNC server supports protocol version 3.889 (viewer 3.8)
We have 5 security types to read
0) Received security type 30
Selecting security type 30 (0/5 in the list)
1) Received security type 33
2) Received security type 36
3) Received security type 2
4) Received security type 35
Selected Security Scheme 30
Connection "$fe091f59-4c01-41ca-a2b8-441e51916690" removed.
Unable to request termination of client process: No such process
All child processes for connection "$fe091f59-4c01-41ca-a2b8-441e51916690" have been terminated.
The important detail is that the Mac advertises standard VNC authentication as security type 2, but the client selects security type 30 instead and exits immediately.
libgcrypt warning
Initially, the following warning was also logged:
Libgcrypt warning: missing initialization - please fix the application
I tested preloading a small library that explicitly initializes libgcrypt before guacd starts. This removed the warning, but the VNC connection still failed at exactly the same point:
Selected Security Scheme 30
Therefore, the missing libgcrypt initialization does not appear to be the underlying cause.
Expected behavior
Termix should successfully connect to macOS Screen Sharing using either:
- standard VNC password authentication, security type
2, or
- supported Apple authentication if Guacamole/libvncclient can handle it correctly
Actual behavior
The Guacamole VNC client selects Apple security type 30, after which the VNC child process exits without a useful authentication error.
Suggested fix
Possible approaches:
- Allow the user to select or force the VNC security type.
- Prefer standard VNC authentication (
type 2) when only a VNC password is configured.
- Prevent Apple security type
30 from being selected if it is unsupported or unstable in the bundled environment.
- Update or patch the bundled Guacamole/libvncclient integration to correctly support macOS Screen Sharing authentication.
- Return a more specific error to the Termix UI instead of only
Aborted. See logs.
Additional note
SSH and RDP connections from the same Termix installation work correctly. This appears isolated to VNC connections against the built-in macOS Screen Sharing server.
How to Reproduce
See above
Additional Context
No response
Title
VNC connection to macOS Screen Sharing fails after selecting Apple security type 30
Platform
Website - Chrome
Server Installation Method
Proxmox (Community Scripts)
Version
2.5.1
Troubleshooting
The Problem
Description
Termix is unable to establish a VNC connection to a Mac running the built-in macOS Screen Sharing service.
The connection reaches the Mac successfully, and the Mac advertises several supported VNC security types, including standard VNC authentication (
type 2). However, the Guacamole VNC client automatically selects Apple authentication (type 30) and the client process exits immediately afterward.Termix remains stuck on:
or eventually reports:
Environment
macOS configuration
The following settings are enabled:
System Settings → General → Sharing → Screen SharingAllow access for: All usersVNC viewers may control screen with passwordRemote Managementis disabled.The issue occurs both:
Network connectivity
The VNC server is reachable from the Termix host:
Relevant guacd log
With debug logging enabled:
The important detail is that the Mac advertises standard VNC authentication as security type
2, but the client selects security type30instead and exits immediately.libgcrypt warning
Initially, the following warning was also logged:
I tested preloading a small library that explicitly initializes libgcrypt before guacd starts. This removed the warning, but the VNC connection still failed at exactly the same point:
Therefore, the missing libgcrypt initialization does not appear to be the underlying cause.
Expected behavior
Termix should successfully connect to macOS Screen Sharing using either:
2, orActual behavior
The Guacamole VNC client selects Apple security type
30, after which the VNC child process exits without a useful authentication error.Suggested fix
Possible approaches:
type 2) when only a VNC password is configured.30from being selected if it is unsupported or unstable in the bundled environment.Aborted. See logs.Additional note
SSH and RDP connections from the same Termix installation work correctly. This appears isolated to VNC connections against the built-in macOS Screen Sharing server.
How to Reproduce
See above
Additional Context
No response