diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/cli/CreateNullEntity.java b/providers/null/src/main/java/org/onosproject/provider/nil/cli/CreateNullEntity.java
new file mode 100644
index 0000000..ed68dfc
--- /dev/null
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/cli/CreateNullEntity.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.provider.nil.cli;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.primitives.Longs;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.config.basics.BasicElementConfig;
+import org.onosproject.net.edge.EdgePortService;
+import org.onosproject.net.host.HostService;
+import org.onosproject.provider.nil.CustomTopologySimulator;
+import org.onosproject.provider.nil.TopologySimulator;
+
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Base command for adding simulated entities to the custom topology simulation.
+ */
+public abstract class CreateNullEntity extends AbstractShellCommand {
+    protected static final String GEO = "geo";
+    protected static final String GRID = "grid";
+
+    /**
+     * Validates that the simulator is custom.
+     *
+     * @param simulator topology simulator
+     * @return true if valid
+     */
+    protected boolean validateSimulator(TopologySimulator simulator) {
+        if (!(simulator instanceof CustomTopologySimulator)) {
+            error("Custom topology simulator is not active.");
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Validates that the location type is valid.
+     *
+     * @param locType location type
+     * @return true if valid
+     */
+    protected boolean validateLocType(String locType) {
+        if (!(GEO.equals(locType) || GRID.equals(locType))) {
+            error("locType must be 'geo' or 'grid'.");
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Sets the UI location coordinates appropriately.
+     *
+     * @param cfg     element config
+     * @param locType location type
+     * @param latOrY  latitude or Y grid
+     * @param longOrX longitude or X grid
+     */
+    protected void setUiCoordinates(BasicElementConfig cfg,
+                                    String locType, Double latOrY, Double longOrX) {
+        if (latOrY != null && longOrX != null) {
+            cfg.locType(locType);
+            if (GEO.equals(locType)) {
+                cfg.latitude(latOrY).longitude(longOrX);
+            } else {
+                cfg.gridX(longOrX).gridY(latOrY);
+            }
+        }
+        cfg.apply();
+    }
+
+    /**
+     * Finds an available connect point among edge ports of the specified device.
+     *
+     * @param deviceId   device identifier
+     * @param otherPoint optional other point to be excluded from search
+     * @return connect point available for link or host attachment
+     */
+    protected ConnectPoint findAvailablePort(DeviceId deviceId, ConnectPoint otherPoint) {
+        EdgePortService eps = get(EdgePortService.class);
+        HostService hs = get(HostService.class);
+
+        List<ConnectPoint> points = ImmutableList
+                .sortedCopyOf((l, r) -> Longs.compare(l.port().toLong(), r.port().toLong()),
+                              eps.getEdgePoints(deviceId));
+        return points.stream()
+                .filter(p -> !Objects.equals(p, otherPoint) && hs.getConnectedHosts(p).isEmpty())
+                .findFirst().orElse(null);
+    }
+}