Support for NTLM authentication added

To support NTLM authentication, a database is added as an authentication source.
Currently, only the configuration file is supported as a database.
Database authentication supports Basic and NTLM authentication protcols.

ServerConfig.BasicAuthEnabled renamed to LocalEnabled as Basic auth can be used with Database or Local.

README.md

@@ -28,7 +28,7 @@ to connect.
 
 The gateway has several security phases. In the authentication phase the client's credentials are
 verified. Depending the authentication mechanism used, the client's credentials are verified against
-an OpenID Connect provider, Kerberos or a local PAM service.
+an OpenID Connect provider, Kerberos, a local PAM service or a local database.
 
 If OpenID Connect is used the user will
 need to connect to a webpage provided by the gateway to authenticate, which in turn will redirect
@@ -45,6 +45,9 @@ If local authentication is used the client will need to provide a username and p
 against PAM. This requires, to ensure privilege separation, that ```rdpgw-auth``` is also running and a
 valid PAM configuration is provided per typical configuration.
 
+If database authentication is used, the allowed user credentials for the gateway should be configured in the 
+configuration file.
+
 Finally, RDP hosts that the client wants to connect to are verified against what was provided by / allowed by
 the server. Next to that the client's ip address needs to match the one it obtained the gateway token with if
 using OpenID Connect. Due to proxies and NAT this is not always possible and thus can be disabled. However, this
@@ -58,7 +61,7 @@ settings.
 ## Authentication
 
 RDPGW wants to be secure when you set it up from the start. It supports several authentication
-mechanisms such as OpenID Connect, Kerberos and PAM. 
+mechanisms such as OpenID Connect, Kerberos, PAM or a database.
 
 Technically, cookies are encrypted and signed on the client side relying
 on [Gorilla Sessions](https://www.gorillatoolkit.org/pkg/sessions). PAA tokens (gateway access tokens)
@@ -72,7 +75,7 @@ if you want.
 
 ### Mixing authentication mechanisms
 
-It is technically possible to mix authentication mechanisms. Currently, you can mix local and Kerberos. If you enable 
+It is technically possible to mix authentication mechanisms. Currently, you can mix local with Kerberos or database. If you enable 
 OpenID Connect it is not possible to mix it with local or Kerberos at the moment.
 
 ### Open ID Connect
@@ -137,7 +140,7 @@ Caps:
 The client can then connect directly to the gateway without the need for a RDP file.
 
 
-### PAM / Local / Basic Auth
+### PAM / Local (Basic Auth)
 ![PAM](docs/images/flow-pam.svg)
 
 The gateway can also support authentication against PAM. Sometimes this is referred to as local or passwd authentication,
@@ -146,7 +149,7 @@ but it also supports LDAP authentication or even Active Directory if you have th
 `rdpgw-auth` that is used to authenticate the user. This program needs to be run as root or setuid.
 
 __NOTE__: The default windows client ``mstsc`` does not support basic auth. You will need to use a different client or
-switch to OpenID Connect or Kerberos.
+switch to OpenID Connect, Kerberos or database authentication.
 
 __NOTE__: Using PAM for passwd (i.e. LDAP is fine) within a container is not recommended. It is better to use OpenID 
 Connect or Kerberos. If you do want to use it within a container you can choose to run the helper program outside the 
@@ -180,6 +183,33 @@ Make sure to run both the gateway and `rdpgw-auth`. The gateway will connect to
 
 The client can then connect to the gateway directly by using a remote desktop client.
 
+### Database (Basic Auth or NTLM)
+
+The gateway can also support authentication using a local database. 
+Currently, only the configuration file is supported as a database. 
+In the future, support for real databases (e.g. sqlite) may be added.
+
+Database authentication has the advantage that it is easy to setup, especially in case the gateway is used for a limited number of users.
+Unlike PAM / local, database authentication supports the default windows client ``mstsc``.
+
+__WARNING__: The password is currently saved in plain text. So, you should keep the config file as secure as possible and avoid 
+reusing the same password for other applications. The password is stored in plain text to support the NTLM authentication protocol.
+
+To enable database authentication make sure to set the following variables in the configuration file.
+
+```yaml
+Server:
+  Authentication:
+    - database
+Users:
+ - {Username: "username1", Password: "secure_password"} # Modify this password!
+Caps:
+  TokenAuth: false
+```
+
+The client can then connect to the gateway directly by using a remote desktop client using the gateway credentials 
+configured in the YAML configuration file.
+
 ## TLS
 
 The gateway requires a valid TLS certificate. This means a certificate that is signed by a valid CA that is in the store 
@@ -209,16 +239,17 @@ TLS termination.
 ```yaml
 # web server configuration. 
 Server:
- # can be set to openid, kerberos and local. If openid is used rdpgw expects
+ # can be set to openid, kerberos, local and database. If openid is used rdpgw expects
  # a configured openid provider, make sure to set caps.tokenauth to true. If local
  # rdpgw connects to rdpgw-auth over a socket to verify users and password. Note:
  # rdpgw-auth needs to be run as root or setuid in order to work. If kerberos is
- # used a keytab and krb5conf need to be supplied. local and kerberos authentication
- # can be stacked, so that the clients selects what it wants.
+ # used a keytab and krb5conf need to be supplied. local can be stacked with 
+ # kerberos or database authentication, so that the clients selects what it wants.
  Authentication:
   # - kerberos
   # - local
   - openid
+  # - database
  # The socket to connect to if using local auth. Ensure rdpgw auth is configured to
  # use the same socket.
  # AuthSocket: /tmp/rdpgw-auth.sock
@@ -267,6 +298,9 @@ OpenId:
 #  Keytab: /etc/keytabs/rdpgw.keytab
 #  Krb5conf: /etc/krb5.conf
 #  enabled / disabled capabilities
+# Users:
+#  - {Username: "username1", Password: "secure_password"}
+#  - {Username: "username2", Password: "secure_password2"}
 Caps:
  SmartCardAuth: false
  # required for openid connect
@@ -369,12 +403,15 @@ In this way you can integrate, for example, it with [pam-jwt](https://github.com
 ## Client Caveats
 The several clients that Microsoft provides come with their own caveats. 
 The most important one is that the default client on Windows ``mstsc`` does 
-not support basic authentication. This means you need to use either OpenID Connect
-or Kerberos.
+not support basic authentication. This means you need to use either OpenID Connect,
+Kerberos or database authentication.
 
 In addition to that, ``mstsc``, when configuring a gateway directly in the client requires
-you to "save the credentials" for the gateway otherwise the client will not connect at all
-(it won't send any packages to the gateway) and it will keep on asking for new credentials.
+you to either:
+ * "save the credentials" for the gateway
+ * or specify a (random) domain name in the username field (e.g. ``.\username``) when prompted for the gateway credentials,
+
+otherwise the client will not connect at all (it won't send any packages to the gateway) and it will keep on asking for new credentials.
 
 Finally, ``mstsc`` requires a valid certificate on the gateway.
 

cmd/rdpgw/config/configuration.go

@@ -31,6 +31,7 @@ type Configuration struct {
 	Server   ServerConfig   `koanf:"server"`
 	OpenId   OpenIDConfig   `koanf:"openid"`
 	Kerberos KerberosConfig `koanf:"kerberos"`
+        Users    []UserConfig   `koanf:"users"`
 	Caps     RDGCapsConfig  `koanf:"caps"`
 	Security SecurityConfig `koanf:"security"`
 	Client   ClientConfig   `koanf:"client"`
@@ -66,6 +67,11 @@ type OpenIDConfig struct {
 	ClientSecret string `koanf:"clientsecret"`
 }
 
+type UserConfig struct {
+	Username             string   `koanf:"username"`
+	Password             string   `koanf:"password"`
+}
+
 type RDGCapsConfig struct {
 	SmartCardAuth   bool `koanf:"smartcardauth"`
 	TokenAuth       bool `koanf:"tokenauth"`
@@ -184,6 +190,7 @@ func Load(configFile string) Configuration {
 	k.UnmarshalWithConf("Security", &Conf.Security, koanfTag)
 	k.UnmarshalWithConf("Client", &Conf.Client, koanfTag)
 	k.UnmarshalWithConf("Kerberos", &Conf.Kerberos, koanfTag)
+        k.UnmarshalWithConf("Users", &Conf.Users, koanfTag)
 
 	if len(Conf.Security.PAATokenEncryptionKey) != 32 {
 		Conf.Security.PAATokenEncryptionKey, _ = security.GenerateRandomString(32)
@@ -221,9 +228,13 @@ func Load(configFile string) Configuration {
 		log.Fatalf("host selection is set to `signed` but `querytokensigningkey` is not set")
 	}
 
-	if Conf.Server.BasicAuthEnabled() && Conf.Server.Tls == "disable" {
+	if Conf.Server.LocalEnabled() && Conf.Server.Tls == "disable" {
 		log.Fatalf("basicauth=local and tls=disable are mutually exclusive")
 	}
+
+        if Conf.Server.DatabaseEnabled() && Conf.Server.KerberosEnabled() {
+                log.Fatalf("database and kerberos authentication are not stackable")
+        }
 
 	if !Conf.Caps.TokenAuth && Conf.Server.OpenIDEnabled() {
 		log.Fatalf("openid is configured but tokenauth disabled")
@@ -250,10 +261,14 @@ func (s *ServerConfig) KerberosEnabled() bool {
 	return s.matchAuth("kerberos")
 }
 
-func (s *ServerConfig) BasicAuthEnabled() bool {
+func (s *ServerConfig) LocalEnabled() bool {
 	return s.matchAuth("local") || s.matchAuth("basic")
 }
 
+func (s *ServerConfig) DatabaseEnabled() bool {
+	return s.matchAuth("database")
+}
+
 func (s *ServerConfig) matchAuth(needle string) bool {
 	for _, q := range s.Authentication {
 		if q == needle {

cmd/rdpgw/database/config.go

@@ -0,0 +1,25 @@
+package database
+
+import (
+        "github.com/bolkedebruin/rdpgw/cmd/rdpgw/config"
+)
+
+type Config struct {
+	users map[string]config.UserConfig
+}
+
+func NewConfig(users []config.UserConfig) *Config {
+        usersMap := map[string]config.UserConfig{}
+
+        for _, user := range users {
+                usersMap[user.Username] = user
+        }
+
+	return &Config{
+		users: usersMap,
+	}
+}
+
+func (c *Config) GetPassword (username string) string {
+        return c.users[username].Password
+}

cmd/rdpgw/database/database.go

@@ -0,0 +1,5 @@
+package database
+
+type Database interface {
+        GetPassword (username string) string
+}

cmd/rdpgw/main.go

@@ -8,6 +8,7 @@ import (
 	"github.com/bolkedebruin/gokrb5/v8/service"
 	"github.com/bolkedebruin/gokrb5/v8/spnego"
 	"github.com/bolkedebruin/rdpgw/cmd/rdpgw/config"
+        "github.com/bolkedebruin/rdpgw/cmd/rdpgw/database"
 	"github.com/bolkedebruin/rdpgw/cmd/rdpgw/kdcproxy"
 	"github.com/bolkedebruin/rdpgw/cmd/rdpgw/protocol"
 	"github.com/bolkedebruin/rdpgw/cmd/rdpgw/security"
@@ -221,19 +222,38 @@ func main() {
 		r.HandleFunc("/callback", o.HandleCallback)
 
 		// only enable un-auth endpoint for openid only config
-		if !conf.Server.KerberosEnabled() || !conf.Server.BasicAuthEnabled() {
+		if !conf.Server.KerberosEnabled() && !conf.Server.LocalEnabled() && !conf.Server.DatabaseEnabled() {
 			rdp.Name("gw").HandlerFunc(gw.HandleGatewayProtocol)
 		}
 	}
 
 	// for stacking of authentication
 	auth := web.NewAuthMux()
 	rdp.MatcherFunc(web.NoAuthz).HandlerFunc(auth.SetAuthenticate)
+
+        var db database.Database
+
+        // database
+        if conf.Server.DatabaseEnabled() {
+                log.Printf("enabling database authentication")
+                db = database.NewConfig(conf.Users)
+                ntlm := web.NewNTLMAuthHandler(db)
+                rdp.NewRoute().HeadersRegexp("Authorization", "NTLM").HandlerFunc(ntlm.NTLMAuth(gw.HandleGatewayProtocol))
+                rdp.NewRoute().HeadersRegexp("Authorization", "Negotiate").HandlerFunc(ntlm.NTLMAuth(gw.HandleGatewayProtocol))
+                auth.Register(`NTLM`)
+        }
 
 	// basic auth
-	if conf.Server.BasicAuthEnabled() {
-		log.Printf("enabling basic authentication")
-		q := web.BasicAuthHandler{SocketAddress: conf.Server.AuthSocket, Timeout: conf.Server.BasicAuthTimeout}
+	if conf.Server.LocalEnabled() || conf.Server.DatabaseEnabled() {
+		q := web.BasicAuthHandler{}
+                if conf.Server.LocalEnabled() {
+                        log.Printf("enabling local authentication")
+                        q.SocketAddress = conf.Server.AuthSocket
+                        q.Timeout = conf.Server.BasicAuthTimeout
+                }
+                if conf.Server.DatabaseEnabled() {
+                        q.Database = db
+                }
 		rdp.NewRoute().HeadersRegexp("Authorization", "Basic").HandlerFunc(q.BasicAuth(gw.HandleGatewayProtocol))
 		auth.Register(`Basic realm="restricted", charset="UTF-8"`)
 	}

cmd/rdpgw/web/basic.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"context"
+        "github.com/bolkedebruin/rdpgw/cmd/rdpgw/database"
 	"github.com/bolkedebruin/rdpgw/cmd/rdpgw/identity"
 	"github.com/bolkedebruin/rdpgw/shared/auth"
 	"google.golang.org/grpc"
@@ -19,38 +20,16 @@ const (
 type BasicAuthHandler struct {
 	SocketAddress string
 	Timeout       int
+        Database      database.Database
 }
 
 func (h *BasicAuthHandler) BasicAuth(next http.HandlerFunc) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		username, password, ok := r.BasicAuth()
 		if ok {
-			ctx := r.Context()
+			authenticated := h.authenticate(w, r, username, password)
 
-			conn, err := grpc.Dial(h.SocketAddress, grpc.WithTransportCredentials(insecure.NewCredentials()),
-				grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
-					return net.Dial(protocolGrpc, addr)
-				}))
-			if err != nil {
-				log.Printf("Cannot reach authentication provider: %s", err)
-				http.Error(w, "Server error", http.StatusInternalServerError)
-				return
-			}
-			defer conn.Close()
-
-			c := auth.NewAuthenticateClient(conn)
-			ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(h.Timeout))
-			defer cancel()
-
-			req := &auth.UserPass{Username: username, Password: password}
-			res, err := c.Authenticate(ctx, req)
-			if err != nil {
-				log.Printf("Error talking to authentication provider: %s", err)
-				http.Error(w, "Server error", http.StatusInternalServerError)
-				return
-			}
-
-			if !res.Authenticated {
+			if !authenticated {
 				log.Printf("User %s is not authenticated for this service", username)
 			} else {
 				log.Printf("User %s authenticated", username)
@@ -61,7 +40,6 @@ func (h *BasicAuthHandler) BasicAuth(next http.HandlerFunc) http.HandlerFunc {
 				next.ServeHTTP(w, identity.AddToRequestCtx(id, r))
 				return
 			}
-
 		}
 		// If the Authentication header is not present, is invalid, or the
 		// username or password is wrong, then set a WWW-Authenticate
@@ -71,3 +49,50 @@ func (h *BasicAuthHandler) BasicAuth(next http.HandlerFunc) http.HandlerFunc {
 		http.Error(w, "Unauthorized", http.StatusUnauthorized)
 	}
 }
+
+func (h *BasicAuthHandler) authenticate(w http.ResponseWriter, r *http.Request, username string, password string) (authenticated bool) {
+        return h.authenticateDatabase(username, password) ||
+               h.authenticateSocket(w, r, username, password)
+}
+
+func (h *BasicAuthHandler) authenticateSocket(w http.ResponseWriter, r *http.Request, username string, password string) (authenticated bool) {
+        if h.SocketAddress == "" {
+                return false
+        }
+
+        ctx := r.Context()
+
+        conn, err := grpc.Dial(h.SocketAddress, grpc.WithTransportCredentials(insecure.NewCredentials()),
+                grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
+                        return net.Dial(protocolGrpc, addr)
+                }))
+        if err != nil {
+                log.Printf("Cannot reach authentication provider: %s", err)
+                http.Error(w, "Server error", http.StatusInternalServerError)
+                return false
+        }
+        defer conn.Close()
+
+        c := auth.NewAuthenticateClient(conn)
+        ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(h.Timeout))
+        defer cancel()
+
+        req := &auth.UserPass{Username: username, Password: password}
+        res, err := c.Authenticate(ctx, req)
+        if err != nil {
+                log.Printf("Error talking to authentication provider: %s", err)
+                http.Error(w, "Server error", http.StatusInternalServerError)
+                return false
+        }
+
+        return res.Authenticated
+}
+
+func (h *BasicAuthHandler) authenticateDatabase(username string, password string) (authenticated bool) {
+        if h.Database == nil {
+                return false
+        }
+
+        expectedPassword := h.Database.GetPassword (username)
+        return expectedPassword != "" && password == expectedPassword
+}