diff --git a/src/confd_gnmi_api_adapter.py b/src/confd_gnmi_api_adapter.py
index 368b2f6..0851fb1 100644
--- a/src/confd_gnmi_api_adapter.py
+++ b/src/confd_gnmi_api_adapter.py
@@ -36,6 +36,13 @@ class GnmiConfDApiServerAdapter(GnmiServerAdapter):
     monitor_external_changes: bool = ApiAdapterDefaults.MONITOR_EXTERNAL_CHANGES
     external_port: int = ApiAdapterDefaults.EXTERNAL_PORT
 
+    class AuthenticationException(Exception):
+        def __init__(self, user, reason="N/A"):
+            self.user = user
+            self.reason = reason
+        def __str__(self):
+            return f"Authentication failed for user '{self.user}': {self.reason}."
+
     def __init__(self):
         self.addr: str = GnmiConfDApiServerAdapter.addr
         self.port: int = GnmiConfDApiServerAdapter.port
@@ -404,10 +411,21 @@ def get_subscription_handler(self,
         log.debug("<== handler=%s", handler)
         return handler
 
-    def set_credentials(self, username="admin", password="admin"):
+    def authenticate(self, username="admin", password="admin"):
         log.info("==> username=%s password=:-)", username)
         self.username = username
         self.password = password
+        auth_status = maapi.Maapi().authenticate(self.username, self.password, 1)
+        reason = "N/A"
+        if not isinstance(auth_status, int):
+            reason = auth_status[1]
+            auth_status = auth_status[0]
+        if auth_status == 1:
+            log.info(f"Authenticated {self.username}.")
+        else:
+            e =  self.AuthenticationException(self.username, str(reason))
+            log.warning(e)
+            raise e
         log.info("<== self.username=%s self.password=:-)", self.username)
 
     # https://tools.ietf.org/html/rfc6022#page-8
@@ -536,7 +554,7 @@ def make_updates_with_maagic_rec(self, tr, node):
             elif isinstance(node, maagic.Leaf):
                 yield from self.append_update(tr, node._path, node._cs_node)
             else:
-                if hasattr(node, "_children"): # skip nodes w/o children, e.g. Action
+                if hasattr(node, "_children"):  # skip nodes w/o children, e.g. Action
                     children = node._children.get_children(node._backend, node)
                     if len(children) == 0 and isinstance(node,
                                                          maagic.PresenceContainer):
diff --git a/src/confd_gnmi_servicer.py b/src/confd_gnmi_servicer.py
index aac5744..406c749 100755
--- a/src/confd_gnmi_servicer.py
+++ b/src/confd_gnmi_servicer.py
@@ -42,7 +42,7 @@ def get_and_connect_adapter(self, username, password):
         elif self.adapter_type == AdapterType.API:
             from confd_gnmi_api_adapter import GnmiConfDApiServerAdapter
             adapter = GnmiConfDApiServerAdapter.get_adapter()
-            adapter.set_credentials(username=username, password=password)
+            adapter.authenticate(username=username, password=password)
         log.debug("<== adapter=%s", adapter)
         return adapter
 
diff --git a/tests/test_client_server_confd.py b/tests/test_client_server_confd.py
index e8f20e3..fe3944e 100644
--- a/tests/test_client_server_confd.py
+++ b/tests/test_client_server_confd.py
@@ -6,10 +6,12 @@
 
 import pytest
 
+import grpc
 import gnmi_pb2
 from client_server_test_base import GrpcBase
 from confd_gnmi_common import make_gnmi_path, make_xpath_path
 from confd_gnmi_server import AdapterType
+from confd_gnmi_client import ConfDgNMIClient
 from route_status import RouteData, RouteProvider, ChangeOp
 from utils.utils import log
 sys.path.append(os.getenv('CONFD_DIR')+"/src/confd/pyapi/confd")
@@ -177,3 +179,17 @@ def test_subscribe_stream_on_change_api_state(self, request):
             RouteProvider.stop_confd_loop()
             confd_thread.join()
             RouteProvider.close_dp()
+
+    def _assert_auth(self, err_string, username="admin", password="admin"):
+        client = ConfDgNMIClient(username=username, password=password, insecure=True)
+        with pytest.raises(grpc.RpcError) as err:
+            capabilities = client.get_capabilities()
+        client.close()
+        assert err_string in str(err)
+
+    @pytest.mark.confd
+    def test_authentication(self, request):
+        log.info("testing authentication")
+        self._assert_auth("Bad password", password="bad")
+        self._assert_auth("No such local user", username="bad", password="bad")
+        self._assert_auth("No such local user", username="bad")