sshbox

SSH into a fresh Docker container. Every connection gets a new Alpine shell; disconnect and the container is gone.

disconnect, and the container is gone

a real pty -- history and vi work, not just piped text

It's a single static binary and one TOML file. Point it at a Docker socket and it works.

Why

Give it to a friend, a co-worker, or just test something out in a disposable environment -- they get a real Alpine box, and it's gone the moment they disconnect, nothing left running that you forgot about.

Handy for home-server setups too: point people at it and they get instant Linux access, no real account and no container to remember to clean up afterward.

Security model

sshbox accepts any username and password -- authentication is left to whatever sits in front of it (Tailscale, a VPN, a bastion). Don't expose port 2222 straight to the internet.

Every connection gets its own container: nothing from the host mounted in, no network access by default, capped at 256MB memory and half a CPU, killed the moment you disconnect. That isolates sessions from each other and from the host, but it's not a hardened sandbox against someone actively trying to break out.

_{rm -rf / inside the container -- disconnect, reconnect, like it never happened}

Getting started

Docker needs to be running first (docker info should succeed) -- brew install --cask docker on macOS, curl -fsSL https://get.docker.com | sh on Linux, or Docker Desktop on Windows. No Go required if you're using a prebuilt binary.

Grab the archive for your platform from the latest release and extract it, e.g.:

curl -LO https://github.com/kknxzz/sshbox/releases/download/v1.1.0/sshbox_1.1.0_linux_amd64.tar.gz
tar -xzf sshbox_1.1.0_linux_amd64.tar.gz
cd sshbox_1.1.0_linux_amd64

(swap the filename for your OS/arch -- Windows ships as a .zip)

Optional -- verify the download against checksums.txt from the same release:

shasum -a 256 -c checksums.txt --ignore-missing   # sha256sum on Linux

Run it, then connect from another terminal:

./bin/sshbox

ssh -p 2222 anyone@localhost

Any username and password gets in. Exit or disconnect and the container is destroyed -- docker ps -a won't show it. Worth skimming the archive's README.txt too -- quick reference for flags and config.

Building from source instead: git clone the repo (needs Go) and go run ., or grab the source-only archive from the release (sshbox_1.1.0_source.tar.gz, no docs or media) and go build ..

Config

sshbox reads config.toml from the current directory by default. Every field has a matching flag that overrides the file if passed; point at a different file with --config path/to/file.toml.

Field	Flag	Default	Meaning
listen_addr	--listen	:2222	address the SSH server binds to
image	--image	alpine:latest	image to run per session
shell	--shell	/bin/sh	command run inside the container
network	--network	none	Docker network mode
memory	--memory	256m	Docker memory limit
cpus	--cpus	0.5	Docker CPU limit
idle_timeout	--idle-timeout	10m	disconnect after this long with no activity
host_key_path	--host-key	host_key	where the ssh host key is stored, generated on first run
runtime	--runtime	docker	container runtime binary -- docker or podman

Limitations

• No authentication -- see Security model above.
• Single node only, no clustering, no remote Docker hosts.
• No persistent storage -- nothing carries between sessions.
• No SFTP, SCP, or port forwarding.
• No Docker Compose -- one image, one container, per session.
• Linux containers only.
• alpine:latest is barebones -- no curl, no sudo, no bash, just busybox and apk. apk add curl works fine manually, it just doesn't persist. Point image at something fuller if that's annoying.
• PTY support covers normal interactive shells: colors, resize, history. Full-screen apps with unusual escape sequences aren't tested exhaustively.

Contributing

PRs welcome -- see CONTRIBUTING.md for style notes. Issues labeled good-first-issue are a good place to start. Star it if you find it useful.

License

MIT