Connect to a screen with VNC

Updated June 29, 2026

VNC lets you see and control another computer’s screen — Linux, Windows, a Mac, a Raspberry Pi, a NAS… Bifrost speaks standard VNC (the RFB protocol), so it works with common servers like macOS Screen Sharing, RealVNC, TightVNC and TigerVNC.

1. Add a VNC connection

Create a connection, set the protocol to VNC, then fill in:

  • Host — the machine’s name or IP address.
  • Port — defaults to 5900 (display :0; use 5901 for :1, etc.).
  • Password — the VNC password, via a credential or typed inline. A username is optional — most VNC servers use a password only, but Bifrost will ask for a username at connect time if the server requires one.

2. Display

In the connection’s VNC settings:

  • Scaling (on by default) — fits the remote screen to your window, keeping its aspect ratio (letterboxed). Turn it off to view at 1:1.
  • Full screen — opens the session full-screen in its own window.
  • Color depth — True Color (24-bit) by default; drop to High Color (16-bit) or 256 colors (8-bit) to save bandwidth on slow links.
  • View-only — watch without sending any keyboard or mouse input. You can make it the default for a connection, or do it just once: from the sidebar, Connect View-Only opens that session read-only without changing its settings.

3. Input, clipboard and shared sessions

  • Clipboard (on by default) — copy/paste text between your Mac and the remote screen.
  • Shared session (on by default) — connect alongside anyone already viewing the screen instead of kicking them off. Turn it off to request an exclusive session (the server decides whether to honor it).
  • Right-click is forwarded to the remote (it acts as the remote’s right mouse button), so there’s no local context menu over the screen.
  • Ctrl+Alt+Del — just press ⌃⌥⌦ (Control-Option-Forward Delete; Forward Delete is fn+Delete on laptops). Bifrost forwards it to the remote, which is handy at a Windows login screen over VNC.
  • View-only blocks all input (keyboard and mouse); the clipboard can still update.

4. Keep VNC secure — tunnel it over SSH

Plain VNC traffic is not encrypted. On a trusted local network that’s usually fine, but over the internet or any untrusted link you should tunnel VNC through SSH:

  1. Create an SSH tunnel connection in Bifrost that forwards a local port (e.g. 5900) to the remote’s localhost:5900.
  2. Point your VNC connection at localhost (and the forwarded port).

Your screen traffic then rides inside the encrypted SSH channel. (See the SSH connection article for keys and tunnels.)

5. Connecting to a Mac

To control another Mac, enable VNC on it: System Settings → General → Sharing → Screen Sharing. Then, in Screen Sharing’s options, turn on “VNC viewers may control screen with password” and set a password — Bifrost uses that standard VNC password (it doesn’t use the Apple Remote Desktop login).

6. Set defaults once, per group

VNC options cascade: app defaults → group → connection. Set your common choices (port, scaling, color depth, view-only, clipboard, shared) on a group, and connections inside inherit them — override any of them per connection when needed.

Troubleshooting

  • Can’t connect / connection refused — confirm a VNC server is actually running and the port is right (5900 for display :0). For a Mac, make sure Screen Sharing is on.
  • Authentication fails on a Mac — enable “VNC viewers may control screen with password” in Screen Sharing and use that password (not your macOS account password).
  • It asks for a username — some servers require one; set it on the connection (or in the credential).
  • Everything is tiny or letterboxed — toggle Scaling, or resize the window; the remote display keeps its aspect ratio.
  • Laggy over the internet — lower the color depth, and tunnel over SSH (also encrypts the session).
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