diff --git a/tcsfw/builder_backend.py b/tcsfw/builder_backend.py
index 6601b2a..0b8e9a9 100644
--- a/tcsfw/builder_backend.py
+++ b/tcsfw/builder_backend.py
@@ -17,7 +17,7 @@
 from tcsfw.batch_import import BatchImporter, LabelFilter
 from tcsfw.claim_coverage import RequirementClaimMapper
 from tcsfw.client_api import APIRequest, ClientPrompt
-from tcsfw.components import CookieData, Cookies, DataReference, DataStorages, Software
+from tcsfw.components import CookieData, Cookies, DataReference, DataStorages, OperatingSystem, Software
 from tcsfw.coverage_result import CoverageReport
 from tcsfw.entity import ClaimAuthority, Entity
 from tcsfw.event_interface import PropertyEvent
@@ -26,7 +26,7 @@
 from tcsfw.main import (ARP, DHCP, DNS, EAPOL, ICMP, NTP, SSH, HTTP, TCP, UDP, IP, TLS,
                         BLEAdvertisement, ClaimBuilder, ClaimSetBuilder, ConnectionBuilder,
                         CookieBuilder, HostBuilder, NodeBuilder, NodeVisualBuilder,
-                        ConfigurationException, ProtocolConfigurer, ProtocolType,
+                        ConfigurationException, OSBuilder, ProtocolConfigurer, ProtocolType,
                         SensitiveDataBuilder, ServiceBuilder, ServiceGroupBuilder, ServiceOrGroup,
                         SoftwareBuilder, SystemBuilder, VisualizerBuilder)
 from tcsfw.main_tools import EvidenceLoader, NodeManipulator, SubLoader, ToolPlanLoader
@@ -379,6 +379,9 @@ def serve(self, *protocols: ProtocolType) -> Self:
             self / p  # pylint: disable=pointless-statement
         return self
 
+    def os(self) -> OSBuilder:
+        return OSBackend(self)
+
     def __lshift__(self, multicast: ServiceBackend) -> 'ConnectionBackend':
         mc = multicast.entity
         assert mc.is_multicast(), "Can only receive multicast"
@@ -849,6 +852,15 @@ class ProtocolConfigurers:
     }
 
 
+class OSBackend(OSBuilder):
+    """OS builder backend"""
+    def __init__(self, parent: HostBackend):
+        self.component = OperatingSystem.get_os(parent.entity)
+
+    def processes(self, owner_process: Dict[str, List[str]]) -> 'OSBuilder':
+        self.component.process_map.update(owner_process)
+
+
 class ClaimBackend(ClaimBuilder):
     """Claim builder"""
 
diff --git a/tcsfw/components.py b/tcsfw/components.py
index df840f6..9fd8295 100644
--- a/tcsfw/components.py
+++ b/tcsfw/components.py
@@ -106,6 +106,23 @@ class SoftwareComponent:
     version: str = ""
 
 
+class OperatingSystem(NodeComponent):
+    """Operating system"""
+    def __init__(self, entity: NetworkNode):
+        super().__init__(entity, "OS")
+        self.process_map: Dict[str, List[str]] = {}  # owner: process names
+
+    @classmethod
+    def get_os(cls, entity: NetworkNode) -> 'OperatingSystem':
+        """Get the OS for network node"""
+        for c in entity.components:
+            if isinstance(c, OperatingSystem):
+                return c
+        c = OperatingSystem(entity)
+        entity.components.append(c)
+        return c
+
+
 class DataStorages(NodeComponent):
     """Data storages in IoT system or network node"""
     def __init__(self, entity: NetworkNode, name="Sensitive data", data: List[SensitiveData] = None):
diff --git a/tcsfw/main.py b/tcsfw/main.py
index cbe6ee9..1793d4f 100644
--- a/tcsfw/main.py
+++ b/tcsfw/main.py
@@ -165,6 +165,10 @@ def use_data(self, *data: 'SensitiveDataBuilder') -> Self:
         """This host uses some sensitive data"""
         raise NotImplementedError()
 
+    def os(self) -> 'OSBuilder':
+        """Operating System definitions"""
+        raise NotImplementedError()
+
     def __truediv__(self, protocol: ProtocolType) -> ServiceBuilder:
         """Pick or add the configured protocol"""
         raise NotImplementedError()
@@ -353,6 +357,13 @@ def __init__(self, event_type: int):
         self.event_type = event_type
 
 
+class OSBuilder:
+    """Operating System builder"""
+    def processes(self, owner_process: Dict[str, List[str]]) -> 'OSBuilder':
+        """Define processes: mapping from owner to list of processes"""
+        raise NotImplementedError()
+
+
 class ClaimBuilder:
     """Claim builder"""
     def key(self, *segments: str) -> Self: