#SSH

Use standard SSH clients to open a shell inside a sandbox or copy files with scp. Sandbox0 terminates SSH at a region-scoped ssh-gateway, authenticates the user from uploaded SSH public keys, and bridges the session into the sandbox runtime.

Connection Model#

The gateway uses the SSH username to decide which sandbox to connect to. Your uploaded public key identifies the user, and the platform still enforces normal sandbox authorization before opening the session.

Use s0 sandbox get to read the connection info instead of hard-coding a region host:

bash
s0 sandbox get "$SANDBOX_ID"

The table output includes SSH Host, SSH Port, and SSH Username when SSH is available for the sandbox. Use s0 -o json sandbox get "$SANDBOX_ID" when you want to script against the same fields.

Manage SSH Public Keys#

Upload your SSH public key once, then reuse standard ssh, SFTP-backed scp, and sftp clients.

Create a key if you do not already have one:

bash
ssh-keygen -t ed25519 -f ~/.ssh/sandbox0_ed25519 -C "sandbox0"

Upload the public key with the s0 CLI:

bash
s0 user ssh-key add --public-key-file ~/.ssh/sandbox0_ed25519.pub

You can also pass the public key inline. Inline keys require an explicit name:

bash
s0 user ssh-key add --name laptop --public-key "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIExample user@host"

List the keys currently attached to your user:

bash
s0 user ssh-key list

Delete a key you no longer want to trust. Use the key ID from s0 user ssh-key list:

bash
s0 user ssh-key delete "$SSH_KEY_ID"

Connect to a Sandbox#

Read SSH Host, SSH Port, and SSH Username from s0 sandbox get, then connect with a standard SSH client.

Fetch the connection info:

bash
s0 sandbox get "$SANDBOX_ID"

For scripts, extract the same fields from JSON output:

bash
SANDBOX_JSON="$(s0 -o json sandbox get "$SANDBOX_ID")"
SSH_HOST="$(printf '%s' "$SANDBOX_JSON" | jq -r '.ssh.host')"
SSH_PORT="$(printf '%s' "$SANDBOX_JSON" | jq -r '.ssh.port')"
SSH_USER="$(printf '%s' "$SANDBOX_JSON" | jq -r '.ssh.username')"
ssh -i ~/.ssh/sandbox0_ed25519 -p "$SSH_PORT" "$SSH_USER@$SSH_HOST"

Run a one-shot remote command instead of opening an interactive shell:

bash
ssh -i ~/.ssh/sandbox0_ed25519 -p "$SSH_PORT" "$SSH_USER@$SSH_HOST" 'uname -a'

If the sandbox is paused, ssh-gateway asks the control plane to resume it before attaching the session.

Copy Files with scp#

Use scp to upload or download files when your OpenSSH client uses SFTP-backed mode. This is the default in OpenSSH 9.0 and newer. On OpenSSH 8.x, use the sftp command instead because its scp client speaks the legacy SCP protocol.

Upload a local file:

bash
scp -i ~/.ssh/sandbox0_ed25519 -P "$SSH_PORT" ./build.log "$SSH_USER@$SSH_HOST:/workspace/build.log"

Download a file from the sandbox:

bash
scp -i ~/.ssh/sandbox0_ed25519 -P "$SSH_PORT" "$SSH_USER@$SSH_HOST:/workspace/output.txt" ./output.txt

Because file transfer runs over the SFTP subsystem here, sftp clients work too:

bash
sftp -i ~/.ssh/sandbox0_ed25519 -P "$SSH_PORT" "$SSH_USER@$SSH_HOST"

Operational Notes#

• SSH authorization stays at the platform layer. You do not manage authorized_keys inside each sandbox.
• Uploaded SSH public keys belong to the user account, not to one sandbox.
• A key can access any sandbox that the user is authorized to access in that region.
• SSH is best for human shell access and standard file transfer. For programmatic process control, use Contexts, or use Supervised Sessions when reconnect and runtime recovery matter.

Next Steps#