SSH

cmux ssh creates a workspace for a remote machine. Browser panes route through the remote network, files drag-and-drop via scp, coding agents send notifications to your local sidebar, and sessions reconnect on drops.

Usage

cmux ssh user@remote
cmux ssh user@remote --name "dev server"
cmux ssh user@remote --command 'omp "investigate auth"'
cmux ssh user@remote -p 2222
cmux ssh user@remote -i ~/.ssh/id_ed25519
cmux ssh user@remote --transport mosh
cmux mosh user@remote
cmux mosh-tmux user@remote
cmux mosh-tmux user@remote --session agent-main

cmux ssh reads your ~/.ssh/config for host aliases, identity files, and proxy settings. All flags mirror their ssh equivalents.

Flags

Mosh terminal transport

Use cmux ssh user@remote --transport mosh when the interactive terminal should survive Wi-Fi, VPN, hotspot, and sleep/wake network changes. Mosh carries only the terminal PTY; SSH remains the management lane for remote metadata, daemon bootstrap and control, browser proxying, uploads, and reconnect actions.

cmux requires Mosh 1.4 or later locally and checks for remote mosh-server before launch. If the client is missing or incompatible, the server is missing, or the remote probe fails, cmux explains the reason and continues over SSH.

Create a Mosh workspace that creates or attaches to a named tmux session (default: main). The tmux profile persists across reconnect and app session restore. This is a roaming tmux terminal, not the native mirror from cmux ssh-tmux. --session <name> selects the session; all other flags match cmux mosh. Without Mosh, the same profile runs over SSH.

SSH deep links

Use cmux SSH deep links when a website or tool wants to offer an Open in cmux button. The link opens cmux, shows a confirmation prompt, then runs the equivalent cmux ssh command after the user confirms.

cmux://ssh?host=dev.example.com
cmux://ssh?host=dev.example.com&user=alice&port=2222&title=GPU%20box
cmux://ssh?host=workspace123.vm-ssh.freestyle.sh&user=workspace123%2Csession-token
cmux://ssh?host=dev.example.com&host-key-policy=accept-new&no-focus=true

Use the cmux.com fallback URL for website buttons. It opens the native link and shows the download if cmux is not installed.

https://cmux.com/deeplink/ssh?host=workspace123.vm-ssh.freestyle.sh&user=workspace123%2Csession-token&title=Freestyle

Prompt and rules buttons use the same fallback shape. Commas, colons, and literal plus signs are preserved when they are URL encoded:

https://cmux.com/deeplink/prompt?text=Review%20this%20branch
https://cmux.com/deeplink/rules?name=freestyle&text=Prefer%20commas,%20colons:%20and%20small%20PRs

Use the SVG icon for dashboard buttons, or the PNG logo when a raster image is required:

https://cmux.com/cmux-icon.svg
https://cmux.com/logo.png

Build the fallback URL with URLSearchParams so titles, host aliases, and user names are encoded safely:

const params = new URLSearchParams({
  host: "workspace123.vm-ssh.freestyle.sh",
  user: "workspace123,session-token",
  title: "Freestyle",
});

const href = "https://cmux.com/deeplink/ssh?" + params.toString();

Use cmux:// for the stable app, cmux-nightly:// for Nightly, and cmux-dev:// for Debug or tagged dev builds.

External links cannot pass identity files, raw ssh options, commands, ProxyCommand, or forwarding rules. Put keys, ProxyJump, HostName, and advanced options in ~/.ssh/config instead. cmux displays the command preview and requires the user to trust the SSH target before connecting.

Browser panes

Browser panes in a remote workspace route all HTTP and WebSocket traffic through the remote machine's network. Type localhost:3000 and you're looking at the dev server running on the remote box. No -L flags, no manual port forwarding. Each remote workspace gets an isolated cookie store so sessions are scoped per-connection.

Drag and drop

Drag an image or file into a remote terminal and cmux uploads it via scp through the existing SSH connection. cmux detects the foreground SSH process by TTY and routes the upload through ControlMaster multiplexing.

Notifications

Processes on the remote machine can run cmux commands that execute on your local instance. When a coding agent calls cmux notify on the remote box, the notification appears in your local sidebar. The blue ring lights up on the workspace tab. Cmd+Shift+U jumps to it. Notification spam from flaky connections is suppressed with a per-host cooldown.

Coding agents over SSH

cmux claude-teams and cmux omo both work inside SSH sessions. The Go relay daemon on the remote host handles the same tmux-compat translation that the local Swift CLI does. Teammate agents spawn as native cmux splits on your local machine while computation runs on the remote box.

# Inside an SSH session:
cmux claude-teams
cmux omo

Reconnect

When the connection drops, cmux reconnects with exponential backoff (3s, 6s, 12s, up to 60s). The remote session persists and cmux reattaches on reconnect, resizing with smallest-screen-wins semantics. Default keepalive options (ServerAliveInterval=20, ServerAliveCountMax=2) are injected unless your config already sets them.

Relay daemon

On first connect, cmux probes the remote host (uname -s, uname -m) and uploads a versioned cmuxd-remote binary. The binary speaks JSON-RPC over stdio and handles three things:

The daemon binary is stored at ~/.cmux/bin/cmuxd-remote/<version>/<os>-<arch>/cmuxd-remote on the remote host and verified against a SHA-256 manifest embedded in the app.