NetBird SSH (#361)

This PR adds support for SSH access through the NetBird network
without managing SSH skeys.
NetBird client app has an embedded SSH server (Linux/Mac only) 
and a netbird ssh command.

client/internal/config.go

@@ -3,16 +3,16 @@ package internal
 import (
 	"context"
 	"fmt"
+	"github.com/netbirdio/netbird/client/ssh"
+	"github.com/netbirdio/netbird/iface"
 	mgm "github.com/netbirdio/netbird/management/client"
+	"github.com/netbirdio/netbird/util"
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"net/url"
 	"os"
-
-	"github.com/netbirdio/netbird/iface"
-	"github.com/netbirdio/netbird/util"
-	log "github.com/sirupsen/logrus"
-	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 )
 
 var managementURLDefault *url.URL
@@ -38,12 +38,18 @@ type Config struct {
 	AdminURL       *url.URL
 	WgIface        string
 	IFaceBlackList []string
+	// SSHKey is a private SSH key in a PEM format
+	SSHKey string
 }
 
 // createNewConfig creates a new config generating a new Wireguard key and saving to file
 func createNewConfig(managementURL, adminURL, configPath, preSharedKey string) (*Config, error) {
 	wgKey := generateKey()
-	config := &Config{PrivateKey: wgKey, WgIface: iface.WgInterfaceDefault, IFaceBlackList: []string{}}
+	pem, err := ssh.GeneratePrivateKey(ssh.ED25519)
+	if err != nil {
+		return nil, err
+	}
+	config := &Config{SSHKey: string(pem), PrivateKey: wgKey, WgIface: iface.WgInterfaceDefault, IFaceBlackList: []string{}}
 	if managementURL != "" {
 		URL, err := parseURL("Management URL", managementURL)
 		if err != nil {
@@ -61,7 +67,7 @@ func createNewConfig(managementURL, adminURL, configPath, preSharedKey string) (
 	config.IFaceBlackList = []string{iface.WgInterfaceDefault, "tun0", "zt", "ZeroTier", "utun", "wg", "ts",
 		"Tailscale", "tailscale"}
 
-	err := util.WriteJson(configPath, config)
+	err = util.WriteJson(configPath, config)
 	if err != nil {
 		return nil, err
 	}
@@ -126,6 +132,14 @@ func ReadConfig(managementURL, adminURL, configPath string, preSharedKey *string
 		config.PreSharedKey = *preSharedKey
 		refresh = true
 	}
+	if config.SSHKey == "" {
+		pem, err := ssh.GeneratePrivateKey(ssh.ED25519)
+		if err != nil {
+			return nil, err
+		}
+		config.SSHKey = string(pem)
+		refresh = true
+	}
 
 	if refresh {
 		// since we have new management URL, we need to update config file

client/internal/connect.go

@@ -2,6 +2,7 @@ package internal
 
 import (
 	"context"
+	"github.com/netbirdio/netbird/client/ssh"
 	"time"
 
 	"github.com/netbirdio/netbird/client/system"
@@ -63,8 +64,13 @@ func RunClient(ctx context.Context, config *Config) error {
 		engineCtx, cancel := context.WithCancel(ctx)
 		defer cancel()
 
+		publicSSHKey, err := ssh.GeneratePublicKey([]byte(config.SSHKey))
+		if err != nil {
+			return err
+		}
 		// connect (just a connection, no stream yet) and login to Management Service to get an initial global Wiretrustee config
-		mgmClient, loginResp, err := connectToManagement(engineCtx, config.ManagementURL.Host, myPrivateKey, mgmTlsEnabled)
+		mgmClient, loginResp, err := connectToManagement(engineCtx, config.ManagementURL.Host, myPrivateKey, mgmTlsEnabled,
+			publicSSHKey)
 		if err != nil {
 			log.Debug(err)
 			if s, ok := status.FromError(err); ok && s.Code() == codes.PermissionDenied {
@@ -147,6 +153,7 @@ func createEngineConfig(key wgtypes.Key, config *Config, peerConfig *mgmProto.Pe
 		IFaceBlackList: config.IFaceBlackList,
 		WgPrivateKey:   key,
 		WgPort:         iface.DefaultWgPort,
+		SSHKey:         []byte(config.SSHKey),
 	}
 
 	if config.PreSharedKey != "" {
@@ -179,7 +186,7 @@ func connectToSignal(ctx context.Context, wtConfig *mgmProto.WiretrusteeConfig,
 }
 
 // connectToManagement creates Management Services client, establishes a connection, logs-in and gets a global Wiretrustee config (signal, turn, stun hosts, etc)
-func connectToManagement(ctx context.Context, managementAddr string, ourPrivateKey wgtypes.Key, tlsEnabled bool) (*mgm.GrpcClient, *mgmProto.LoginResponse, error) {
+func connectToManagement(ctx context.Context, managementAddr string, ourPrivateKey wgtypes.Key, tlsEnabled bool, pubSSHKey []byte) (*mgm.GrpcClient, *mgmProto.LoginResponse, error) {
 	log.Debugf("connecting to Management Service %s", managementAddr)
 	client, err := mgm.NewClient(ctx, managementAddr, ourPrivateKey, tlsEnabled)
 	if err != nil {
@@ -193,7 +200,7 @@ func connectToManagement(ctx context.Context, managementAddr string, ourPrivateK
 	}
 
 	sysInfo := system.GetInfo(ctx)
-	loginResp, err := client.Login(*serverPublicKey, sysInfo)
+	loginResp, err := client.Login(*serverPublicKey, sysInfo, pubSSHKey)
 	if err != nil {
 		return nil, nil, err
 	}

client/internal/engine.go

@@ -3,8 +3,10 @@ package internal
 import (
 	"context"
 	"fmt"
+	nbssh "github.com/netbirdio/netbird/client/ssh"
 	"math/rand"
 	"net"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -54,6 +56,9 @@ type EngineConfig struct {
 
 	// UDPMuxSrflxPort default value 0 - the system will pick an available port
 	UDPMuxSrflxPort int
+
+	// SSHKey is a private SSH key in a PEM format
+	SSHKey []byte
 }
 
 // Engine is a mechanism responsible for reacting on Signal and Management stream events and managing connections to the remote peers.
@@ -87,6 +92,9 @@ type Engine struct {
 
 	// networkSerial is the latest CurrentSerial (state ID) of the network sent by the Management service
 	networkSerial uint64
+
+	sshServerFunc func(hostKeyPEM []byte, addr string) (nbssh.Server, error)
+	sshServer     nbssh.Server
 }
 
 // Peer is an instance of the Connection Peer
@@ -111,6 +119,7 @@ func NewEngine(
 		STUNs:         []*ice.URL{},
 		TURNs:         []*ice.URL{},
 		networkSerial: 0,
+		sshServerFunc: nbssh.DefaultSSHServer,
 	}
 }
 
@@ -283,9 +292,14 @@ func (e *Engine) removeAllPeers() error {
 	return nil
 }
 
-// removePeer closes an existing peer connection and removes a peer
+// removePeer closes an existing peer connection, removes a peer, and clears authorized key of the SSH server
 func (e *Engine) removePeer(peerKey string) error {
 	log.Debugf("removing peer from engine %s", peerKey)
+
+	if e.sshServer != nil {
+		e.sshServer.RemoveAuthorizedKey(peerKey)
+	}
+
 	conn, exists := e.peerConns[peerKey]
 	if exists {
 		delete(e.peerConns, peerKey)
@@ -398,12 +412,6 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 	}
 
 	if update.GetNetworkMap() != nil {
-		if update.GetNetworkMap().GetPeerConfig() != nil {
-			err := e.updateConfig(update.GetNetworkMap().GetPeerConfig())
-			if err != nil {
-				return err
-			}
-		}
 		// only apply new changes and ignore old ones
 		err := e.updateNetworkMap(update.GetNetworkMap())
 		if err != nil {
@@ -414,6 +422,49 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 	return nil
 }
 
+func (e *Engine) updateSSH(sshConf *mgmProto.SSHConfig) error {
+	if sshConf.GetSshEnabled() {
+		if runtime.GOOS == "windows" {
+			log.Warnf("running SSH server on Windows is not supported")
+			return nil
+		}
+		// start SSH server if it wasn't running
+		if e.sshServer == nil {
+			//nil sshServer means it has not yet been started
+			var err error
+			e.sshServer, err = e.sshServerFunc(e.config.SSHKey,
+				fmt.Sprintf("%s:%d", e.wgInterface.Address.IP.String(), nbssh.DefaultSSHPort))
+			if err != nil {
+				return err
+			}
+			go func() {
+				// blocking
+				err = e.sshServer.Start()
+				if err != nil {
+					// will throw error when we stop it even if it is a graceful stop
+					log.Debugf("stopped SSH server with error %v", err)
+				}
+				e.syncMsgMux.Lock()
+				defer e.syncMsgMux.Unlock()
+				e.sshServer = nil
+				log.Infof("stopped SSH server")
+			}()
+		} else {
+			log.Debugf("SSH server is already running")
+		}
+	} else {
+		// Disable SSH server request, so stop it if it was running
+		if e.sshServer != nil {
+			err := e.sshServer.Stop()
+			if err != nil {
+				log.Warnf("failed to stop SSH server %v", err)
+			}
+			e.sshServer = nil
+		}
+	}
+	return nil
+}
+
 func (e *Engine) updateConfig(conf *mgmProto.PeerConfig) error {
 	if e.wgInterface.Address.String() != conf.Address {
 		oldAddr := e.wgInterface.Address.String()
@@ -422,9 +473,17 @@ func (e *Engine) updateConfig(conf *mgmProto.PeerConfig) error {
 		if err != nil {
 			return err
 		}
+		e.config.WgAddr = conf.Address
 		log.Infof("updated peer address from %s to %s", oldAddr, conf.Address)
 	}
 
+	if conf.GetSshConfig() != nil {
+		err := e.updateSSH(conf.GetSshConfig())
+		if err != nil {
+			log.Warnf("failed handling SSH server setup %v", e)
+		}
+	}
+
 	return nil
 }
 
@@ -486,6 +545,15 @@ func (e *Engine) updateTURNs(turns []*mgmProto.ProtectedHostConfig) error {
 }
 
 func (e *Engine) updateNetworkMap(networkMap *mgmProto.NetworkMap) error {
+
+	// intentionally leave it before checking serial because for now it can happen that peer IP changed but serial didn't
+	if networkMap.GetPeerConfig() != nil {
+		err := e.updateConfig(networkMap.GetPeerConfig())
+		if err != nil {
+			return err
+		}
+	}
+
 	serial := networkMap.GetSerial()
 	if e.networkSerial > serial {
 		log.Debugf("received outdated NetworkMap with serial %d, ignoring", serial)
@@ -515,6 +583,18 @@ func (e *Engine) updateNetworkMap(networkMap *mgmProto.NetworkMap) error {
 		if err != nil {
 			return err
 		}
+
+		// update SSHServer by adding remote peer SSH keys
+		if e.sshServer != nil {
+			for _, config := range networkMap.GetRemotePeers() {
+				if config.GetSshConfig() != nil && config.GetSshConfig().GetSshPubKey() != nil {
+					err := e.sshServer.AddAuthorizedKey(config.WgPubKey, string(config.GetSshConfig().GetSshPubKey()))
+					if err != nil {
+						log.Warnf("failed adding authroized key to SSH DefaultServer %v", err)
+					}
+				}
+			}
+		}
 	}
 
 	e.networkSerial = serial

client/internal/engine_test.go

@@ -3,6 +3,9 @@ package internal
 import (
 	"context"
 	"fmt"
+	"github.com/netbirdio/netbird/client/ssh"
+	"github.com/netbirdio/netbird/iface"
+	"github.com/stretchr/testify/assert"
 	"net"
 	"os"
 	"path/filepath"
@@ -40,6 +43,140 @@ var (
 	}
 )
 
+func TestEngine_SSH(t *testing.T) {
+
+	if runtime.GOOS == "windows" {
+		t.Skip("skipping TestEngine_SSH on Windows")
+	}
+
+	key, err := wgtypes.GeneratePrivateKey()
+	if err != nil {
+		t.Fatal(err)
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	engine := NewEngine(ctx, cancel, &signal.MockClient{}, &mgmt.MockClient{}, &EngineConfig{
+		WgIfaceName:  "utun101",
+		WgAddr:       "100.64.0.1/24",
+		WgPrivateKey: key,
+		WgPort:       33100,
+	})
+
+	var sshKeysAdded []string
+	var sshPeersRemoved []string
+
+	sshCtx, cancel := context.WithCancel(context.Background())
+
+	engine.sshServerFunc = func(hostKeyPEM []byte, addr string) (ssh.Server, error) {
+		return &ssh.MockServer{
+			Ctx: sshCtx,
+			StopFunc: func() error {
+				cancel()
+				return nil
+			},
+			StartFunc: func() error {
+				<-ctx.Done()
+				return ctx.Err()
+			},
+			AddAuthorizedKeyFunc: func(peer, newKey string) error {
+				sshKeysAdded = append(sshKeysAdded, newKey)
+				return nil
+			},
+			RemoveAuthorizedKeyFunc: func(peer string) {
+				sshPeersRemoved = append(sshPeersRemoved, peer)
+			},
+		}, nil
+	}
+	err = engine.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		err := engine.Stop()
+		if err != nil {
+			return
+		}
+	}()
+
+	peerWithSSH := &mgmtProto.RemotePeerConfig{
+		WgPubKey:   "MNHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
+		AllowedIps: []string{"100.64.0.21/24"},
+		SshConfig: &mgmtProto.SSHConfig{
+			SshPubKey: []byte("ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFATYCqaQw/9id1Qkq3n16JYhDhXraI6Pc1fgB8ynEfQ"),
+		},
+	}
+
+	// SSH server is not enabled so SSH config of a remote peer should be ignored
+	networkMap := &mgmtProto.NetworkMap{
+		Serial:             6,
+		PeerConfig:         nil,
+		RemotePeers:        []*mgmtProto.RemotePeerConfig{peerWithSSH},
+		RemotePeersIsEmpty: false,
+	}
+
+	err = engine.updateNetworkMap(networkMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assert.Nil(t, engine.sshServer)
+
+	// SSH server is enabled, therefore SSH config should be applied
+	networkMap = &mgmtProto.NetworkMap{
+		Serial: 7,
+		PeerConfig: &mgmtProto.PeerConfig{Address: "100.64.0.1/24",
+			SshConfig: &mgmtProto.SSHConfig{SshEnabled: true}},
+		RemotePeers:        []*mgmtProto.RemotePeerConfig{peerWithSSH},
+		RemotePeersIsEmpty: false,
+	}
+
+	err = engine.updateNetworkMap(networkMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(250 * time.Millisecond)
+	assert.NotNil(t, engine.sshServer)
+	assert.Contains(t, sshKeysAdded, "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFATYCqaQw/9id1Qkq3n16JYhDhXraI6Pc1fgB8ynEfQ")
+
+	// now remove peer
+	networkMap = &mgmtProto.NetworkMap{
+		Serial:             8,
+		RemotePeers:        []*mgmtProto.RemotePeerConfig{},
+		RemotePeersIsEmpty: false,
+	}
+
+	err = engine.updateNetworkMap(networkMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	//time.Sleep(250 * time.Millisecond)
+	assert.NotNil(t, engine.sshServer)
+	assert.Contains(t, sshPeersRemoved, "MNHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=")
+
+	// now disable SSH server
+	networkMap = &mgmtProto.NetworkMap{
+		Serial: 9,
+		PeerConfig: &mgmtProto.PeerConfig{Address: "100.64.0.1/24",
+			SshConfig: &mgmtProto.SSHConfig{SshEnabled: false}},
+		RemotePeers:        []*mgmtProto.RemotePeerConfig{peerWithSSH},
+		RemotePeersIsEmpty: false,
+	}
+
+	err = engine.updateNetworkMap(networkMap)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assert.Nil(t, engine.sshServer)
+
+}
+
 func TestEngine_UpdateNetworkMap(t *testing.T) {
 	// test setup
 	key, err := wgtypes.GeneratePrivateKey()
@@ -52,11 +189,12 @@ func TestEngine_UpdateNetworkMap(t *testing.T) {
 	defer cancel()
 
 	engine := NewEngine(ctx, cancel, &signal.MockClient{}, &mgmt.MockClient{}, &EngineConfig{
-		WgIfaceName:  "utun100",
+		WgIfaceName:  "utun102",
 		WgAddr:       "100.64.0.1/24",
 		WgPrivateKey: key,
 		WgPort:       33100,
 	})
+	engine.wgInterface, err = iface.NewWGIFace("utun102", "100.64.0.1/24", iface.DefaultMTU)
 
 	type testCase struct {
 		name       string
@@ -231,7 +369,7 @@ func TestEngine_Sync(t *testing.T) {
 	}
 
 	engine := NewEngine(ctx, cancel, &signal.MockClient{}, &mgmt.MockClient{SyncFunc: syncFunc}, &EngineConfig{
-		WgIfaceName:  "utun100",
+		WgIfaceName:  "utun103",
 		WgAddr:       "100.64.0.1/24",
 		WgPrivateKey: key,
 		WgPort:       33100,
@@ -418,7 +556,7 @@ func createEngine(ctx context.Context, cancel context.CancelFunc, setupKey strin
 	}
 
 	info := system.GetInfo(ctx)
-	resp, err := mgmtClient.Register(*publicKey, setupKey, "", info)
+	resp, err := mgmtClient.Register(*publicKey, setupKey, "", info, nil)
 	if err != nil {
 		return nil, err
 	}

client/internal/login.go

@@ -2,8 +2,8 @@ package internal
 
 import (
 	"context"
-
 	"github.com/google/uuid"
+	"github.com/netbirdio/netbird/client/ssh"
 	"github.com/netbirdio/netbird/client/system"
 	mgm "github.com/netbirdio/netbird/management/client"
 	mgmProto "github.com/netbirdio/netbird/management/proto"
@@ -40,7 +40,11 @@ func Login(ctx context.Context, config *Config, setupKey string, jwtToken string
 		return err
 	}
 
-	_, err = loginPeer(ctx, *serverKey, mgmClient, setupKey, jwtToken)
+	pubSSHKey, err := ssh.GeneratePublicKey([]byte(config.SSHKey))
+	if err != nil {
+		return err
+	}
+	_, err = loginPeer(ctx, *serverKey, mgmClient, setupKey, jwtToken, pubSSHKey)
 	if err != nil {
 		log.Errorf("failed logging-in peer on Management Service : %v", err)
 		return err
@@ -56,13 +60,13 @@ func Login(ctx context.Context, config *Config, setupKey string, jwtToken string
 }
 
 // loginPeer attempts to login to Management Service. If peer wasn't registered, tries the registration flow.
-func loginPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.GrpcClient, setupKey string, jwtToken string) (*mgmProto.LoginResponse, error) {
+func loginPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.GrpcClient, setupKey string, jwtToken string, pubSSHKey []byte) (*mgmProto.LoginResponse, error) {
 	sysInfo := system.GetInfo(ctx)
-	loginResp, err := client.Login(serverPublicKey, sysInfo)
+	loginResp, err := client.Login(serverPublicKey, sysInfo, pubSSHKey)
 	if err != nil {
 		if s, ok := status.FromError(err); ok && s.Code() == codes.PermissionDenied {
 			log.Debugf("peer registration required")
-			return registerPeer(ctx, serverPublicKey, client, setupKey, jwtToken)
+			return registerPeer(ctx, serverPublicKey, client, setupKey, jwtToken, pubSSHKey)
 		} else {
 			return nil, err
 		}
@@ -75,7 +79,7 @@ func loginPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.Grp
 
 // registerPeer checks whether setupKey was provided via cmd line and if not then it prompts user to enter a key.
 // Otherwise tries to register with the provided setupKey via command line.
-func registerPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.GrpcClient, setupKey string, jwtToken string) (*mgmProto.LoginResponse, error) {
+func registerPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.GrpcClient, setupKey string, jwtToken string, pubSSHKey []byte) (*mgmProto.LoginResponse, error) {
 	validSetupKey, err := uuid.Parse(setupKey)
 	if err != nil && jwtToken == "" {
 		return nil, status.Errorf(codes.InvalidArgument, "invalid setup-key or no sso information provided, err: %v", err)
@@ -83,7 +87,7 @@ func registerPeer(ctx context.Context, serverPublicKey wgtypes.Key, client *mgm.
 
 	log.Debugf("sending peer registration request to Management Service")
 	info := system.GetInfo(ctx)
-	loginResp, err := client.Register(serverPublicKey, validSetupKey.String(), jwtToken, info)
+	loginResp, err := client.Register(serverPublicKey, validSetupKey.String(), jwtToken, info, pubSSHKey)
 	if err != nil {
 		log.Errorf("failed registering peer %v,%s", err, validSetupKey.String())
 		return nil, err