TCP

Accessor: client.TCP()

Forward TCP connections to sandbox ports using bidirectional gRPC streaming.

Forward

Open a bidirectional TCP forwarding stream to a specific port inside a sandbox. Returns an io.ReadWriteCloser that proxies data between the caller and the sandbox port over gRPC streaming.

conn, err := client.TCP().Forward(ctx, "default", "sandbox-123", 8080)
if err != nil {
    log.Fatal(err)
}
defer conn.Close()

// Exchange protocol bytes with the service through the tunnel.
_, err = conn.Write([]byte("ping\n"))
if err != nil {
    log.Fatal(err)
}

buf := make([]byte, 4096)
n, err := conn.Read(buf)
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Response: %s\n", buf[:n])

Listen

Bind a local address that forwards every connection to a sandbox port. The returned ForwardListener owns its accept loop and all bridge goroutines; it is a lifecycle handle with Addr and Close, not a net.Listener.

forward, err := client.TCP().Listen(ctx, "default", "sandbox-123", 8080, 0)
if err != nil {
    log.Fatal(err)
}
defer forward.Close()

conn, err := net.Dial("tcp", forward.Addr().String())
if err != nil {
    log.Fatal(err)
}
defer conn.Close()

Do not pass ForwardListener to http.Serve. Dial its address with the client for the protocol exposed by the sandbox service.

TCP forwarding is lower-level than SSH tunneling. Use TCP forwarding when you need direct port access without SSH session overhead.

See also: SSH Tunneling, Error Handling