diff --git a/protocol_legacy.go b/protocol_legacy.go
new file mode 100644
index 00000000..5c23b172
--- /dev/null
+++ b/protocol_legacy.go
@@ -0,0 +1,199 @@
+package headscale
+
+import (
+	"errors"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/gorilla/mux"
+	"github.com/rs/zerolog/log"
+	"gorm.io/gorm"
+	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
+)
+
+// RegistrationHandler handles the actual registration process of a machine
+// Endpoint /machine/:mkey.
+func (h *Headscale) RegistrationHandler(
+	writer http.ResponseWriter,
+	req *http.Request,
+) {
+	vars := mux.Vars(req)
+	machineKeyStr, ok := vars["mkey"]
+	if !ok || machineKeyStr == "" {
+		log.Error().
+			Str("handler", "RegistrationHandler").
+			Msg("No machine ID in request")
+		http.Error(writer, "No machine ID in request", http.StatusBadRequest)
+
+		return
+	}
+
+	body, _ := io.ReadAll(req.Body)
+
+	var machineKey key.MachinePublic
+	err := machineKey.UnmarshalText([]byte(MachinePublicKeyEnsurePrefix(machineKeyStr)))
+	if err != nil {
+		log.Error().
+			Caller().
+			Err(err).
+			Msg("Cannot parse machine key")
+		machineRegistrations.WithLabelValues("unknown", "web", "error", "unknown").Inc()
+		http.Error(writer, "Cannot parse machine key", http.StatusBadRequest)
+
+		return
+	}
+	registerRequest := tailcfg.RegisterRequest{}
+	err = decode(body, &registerRequest, &machineKey, h.privateKey)
+	if err != nil {
+		log.Error().
+			Caller().
+			Err(err).
+			Msg("Cannot decode message")
+		machineRegistrations.WithLabelValues("unknown", "web", "error", "unknown").Inc()
+		http.Error(writer, "Cannot decode message", http.StatusBadRequest)
+
+		return
+	}
+
+	now := time.Now().UTC()
+	machine, err := h.GetMachineByMachineKey(machineKey)
+	if errors.Is(err, gorm.ErrRecordNotFound) {
+		machineKeyStr := MachinePublicKeyStripPrefix(machineKey)
+
+		// If the machine has AuthKey set, handle registration via PreAuthKeys
+		if registerRequest.Auth.AuthKey != "" {
+			h.handleAuthKey(writer, req, machineKey, registerRequest)
+
+			return
+		}
+
+		// Check if the node is waiting for interactive login.
+		//
+		// TODO(juan): We could use this field to improve our protocol implementation,
+		// and hold the request until the client closes it, or the interactive
+		// login is completed (i.e., the user registers the machine).
+		// This is not implemented yet, as it is no strictly required. The only side-effect
+		// is that the client will hammer headscale with requests until it gets a
+		// successful RegisterResponse.
+		if registerRequest.Followup != "" {
+			if _, ok := h.registrationCache.Get(NodePublicKeyStripPrefix(registerRequest.NodeKey)); ok {
+				log.Debug().
+					Caller().
+					Str("machine", registerRequest.Hostinfo.Hostname).
+					Str("node_key", registerRequest.NodeKey.ShortString()).
+					Str("node_key_old", registerRequest.OldNodeKey.ShortString()).
+					Str("follow_up", registerRequest.Followup).
+					Msg("Machine is waiting for interactive login")
+
+				ticker := time.NewTicker(registrationHoldoff)
+				select {
+				case <-req.Context().Done():
+					return
+				case <-ticker.C:
+					h.handleMachineRegistrationNew(writer, req, machineKey, registerRequest)
+
+					return
+				}
+			}
+		}
+
+		log.Info().
+			Caller().
+			Str("machine", registerRequest.Hostinfo.Hostname).
+			Str("node_key", registerRequest.NodeKey.ShortString()).
+			Str("node_key_old", registerRequest.OldNodeKey.ShortString()).
+			Str("follow_up", registerRequest.Followup).
+			Msg("New machine not yet in the database")
+
+		givenName, err := h.GenerateGivenName(registerRequest.Hostinfo.Hostname)
+		if err != nil {
+			log.Error().
+				Caller().
+				Str("func", "RegistrationHandler").
+				Str("hostinfo.name", registerRequest.Hostinfo.Hostname).
+				Err(err)
+
+			return
+		}
+
+		// The machine did not have a key to authenticate, which means
+		// that we rely on a method that calls back some how (OpenID or CLI)
+		// We create the machine and then keep it around until a callback
+		// happens
+		newMachine := Machine{
+			MachineKey: machineKeyStr,
+			Hostname:   registerRequest.Hostinfo.Hostname,
+			GivenName:  givenName,
+			NodeKey:    NodePublicKeyStripPrefix(registerRequest.NodeKey),
+			LastSeen:   &now,
+			Expiry:     &time.Time{},
+		}
+
+		if !registerRequest.Expiry.IsZero() {
+			log.Trace().
+				Caller().
+				Str("machine", registerRequest.Hostinfo.Hostname).
+				Time("expiry", registerRequest.Expiry).
+				Msg("Non-zero expiry time requested")
+			newMachine.Expiry = &registerRequest.Expiry
+		}
+
+		h.registrationCache.Set(
+			newMachine.NodeKey,
+			newMachine,
+			registerCacheExpiration,
+		)
+
+		h.handleMachineRegistrationNew(writer, req, machineKey, registerRequest)
+
+		return
+	}
+
+	// The machine is already registered, so we need to pass through reauth or key update.
+	if machine != nil {
+		// If the NodeKey stored in headscale is the same as the key presented in a registration
+		// request, then we have a node that is either:
+		// - Trying to log out (sending a expiry in the past)
+		// - A valid, registered machine, looking for the node map
+		// - Expired machine wanting to reauthenticate
+		if machine.NodeKey == NodePublicKeyStripPrefix(registerRequest.NodeKey) {
+			// The client sends an Expiry in the past if the client is requesting to expire the key (aka logout)
+			//   https://github.com/tailscale/tailscale/blob/main/tailcfg/tailcfg.go#L648
+			if !registerRequest.Expiry.IsZero() &&
+				registerRequest.Expiry.UTC().Before(now) {
+				h.handleMachineLogOut(writer, req, machineKey, *machine)
+
+				return
+			}
+
+			// If machine is not expired, and is register, we have a already accepted this machine,
+			// let it proceed with a valid registration
+			if !machine.isExpired() {
+				h.handleMachineValidRegistration(writer, req, machineKey, *machine)
+
+				return
+			}
+		}
+
+		// The NodeKey we have matches OldNodeKey, which means this is a refresh after a key expiration
+		if machine.NodeKey == NodePublicKeyStripPrefix(registerRequest.OldNodeKey) &&
+			!machine.isExpired() {
+			h.handleMachineRefreshKey(
+				writer,
+				req,
+				machineKey,
+				registerRequest,
+				*machine,
+			)
+
+			return
+		}
+
+		// The machine has expired
+		h.handleMachineExpired(writer, req, machineKey, registerRequest, *machine)
+
+		return
+	}
+}