diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/config/BlockedPortsConfig.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/config/BlockedPortsConfig.java
new file mode 100644
index 0000000..a5c5557
--- /dev/null
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/config/BlockedPortsConfig.java
@@ -0,0 +1,213 @@
+/*
+ * Copyright 2017-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.segmentrouting.config;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.net.config.Config;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Network config to describe ports that should be blocked until authenticated.
+ */
+public class BlockedPortsConfig extends Config<ApplicationId> {
+
+    /**
+     * Returns the top level keys to the config,
+     * which should be device ID strings.
+     *
+     * @return this list of top level keys
+     */
+    public List<String> deviceIds() {
+        List<String> devIds = new ArrayList<>();
+        if (object != null) {
+            Iterator<String> it = object.fieldNames();
+            if (it != null) {
+                it.forEachRemaining(devIds::add);
+            }
+        }
+        return devIds;
+    }
+
+    /**
+     * Returns the port range strings associated with the given device id key.
+     *
+     * @param deviceId the device id key
+     * @return the associated port range strings
+     */
+    public List<String> portRanges(String deviceId) {
+        List<String> portRanges = new ArrayList<>();
+        if (object != null) {
+            JsonNode jnode = object.get(deviceId);
+            if (ArrayNode.class.isInstance(jnode)) {
+                ArrayNode array = (ArrayNode) jnode;
+                array.forEach(pr -> portRanges.add(pr.asText()));
+            }
+        }
+        return portRanges;
+    }
+
+    /**
+     * Returns an iterator over the port numbers defined by the port ranges
+     * defined in the configuration, for the given device.
+     *
+     * @param deviceId the specific device
+     * @return an iterator over the configured ports
+     */
+    public Iterator<Long> portIterator(String deviceId) {
+        List<String> ranges = portRanges(deviceId);
+        return new PortIterator(ranges);
+    }
+
+    /**
+     * Private implementation of an iterator that aggregates several range
+     * iterators into a single iterator.
+     */
+    class PortIterator implements Iterator<Long> {
+        private final List<Range> ranges;
+        private final int nRanges;
+        private int currentRange = 0;
+        private Iterator<Long> iterator;
+
+        PortIterator(List<String> rangeSpecs) {
+            nRanges = rangeSpecs.size();
+            ranges = new ArrayList<>(nRanges);
+            if (nRanges > 0) {
+                for (String rs : rangeSpecs) {
+                    ranges.add(new Range(rs));
+                }
+                iterator = ranges.get(0).iterator();
+            }
+        }
+
+        @Override
+        public boolean hasNext() {
+            return nRanges > 0 &&
+                    (currentRange < nRanges - 1 ||
+                            (currentRange < nRanges && iterator.hasNext()));
+        }
+
+        @Override
+        public Long next() {
+            if (nRanges == 0) {
+                throw new NoSuchElementException();
+            }
+
+            Long value;
+            if (iterator.hasNext()) {
+                value = iterator.next();
+            } else {
+                currentRange++;
+                if (currentRange < nRanges) {
+                    iterator = ranges.get(currentRange).iterator();
+                    value = iterator.next();
+                } else {
+                    throw new NoSuchElementException();
+                }
+            }
+            return value;
+        }
+    }
+
+    /**
+     * Private implementation of a "range" of long numbers, defined by a
+     * string of the form {@code "<lo>-<hi>"}, for example, "17-32".
+     */
+    static final class Range {
+        private static final Pattern RE_SINGLE = Pattern.compile("(\\d+)");
+        private static final Pattern RE_RANGE = Pattern.compile("(\\d+)-(\\d+)");
+        private static final String E_BAD_FORMAT = "Bad Range Format ";
+
+        private final long lo;
+        private final long hi;
+
+        /**
+         * Constructs a range from the given string definition.
+         * For example:
+         * <pre>
+         *     Range r = new Range("17-32");
+         * </pre>
+         *
+         * @param s the string representation of the range
+         * @throws IllegalArgumentException if the range string is malformed
+         */
+        Range(String s) {
+            String lohi = s;
+            Matcher m = RE_SINGLE.matcher(s);
+            if (m.matches()) {
+                lohi = s + "-" + s;
+            }
+            m = RE_RANGE.matcher(lohi);
+            if (!m.matches()) {
+                throw new IllegalArgumentException(E_BAD_FORMAT + s);
+            }
+            try {
+                lo = Long.parseLong(m.group(1));
+                hi = Long.parseLong(m.group(2));
+
+                if (hi < lo) {
+                    throw new IllegalArgumentException(E_BAD_FORMAT + s);
+                }
+            } catch (NumberFormatException nfe) {
+                // unlikely to be thrown, since the matcher will have failed first
+                throw new IllegalArgumentException(E_BAD_FORMAT + s, nfe);
+            }
+        }
+
+
+        /**
+         * Returns an iterator over this range, starting from the lowest value
+         * and iterating up to the highest value (inclusive).
+         *
+         * @return an iterator over this range
+         */
+        Iterator<Long> iterator() {
+            return new RangeIterator();
+        }
+
+        /**
+         * Private implementation of an iterator over the range.
+         */
+        class RangeIterator implements Iterator<Long> {
+            long current;
+
+            RangeIterator() {
+                current = lo - 1;
+            }
+
+            @Override
+            public boolean hasNext() {
+                return current < hi;
+            }
+
+            @Override
+            public Long next() {
+                if (!hasNext()) {
+                    throw new NoSuchElementException();
+                }
+                return ++current;
+            }
+        }
+    }
+}
diff --git a/apps/segmentrouting/src/test/java/org/onosproject/segmentrouting/config/BlockedPortsConfigTest.java b/apps/segmentrouting/src/test/java/org/onosproject/segmentrouting/config/BlockedPortsConfigTest.java
new file mode 100644
index 0000000..e457896
--- /dev/null
+++ b/apps/segmentrouting/src/test/java/org/onosproject/segmentrouting/config/BlockedPortsConfigTest.java
@@ -0,0 +1,239 @@
+/*
+ * Copyright 2017-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.segmentrouting.config;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Before;
+import org.junit.Test;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.DefaultApplicationId;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+/**
+ * Unit tests for {@link BlockedPortsConfig}.
+ */
+public class BlockedPortsConfigTest {
+
+    private static final ApplicationId APP_ID = new DefaultApplicationId(1, "foo");
+    private static final String KEY = "blocked";
+    private static final ObjectMapper MAPPER = new ObjectMapper();
+
+    private static final String DEV1 = "of:0000000000000001";
+    private static final String DEV2 = "of:0000000000000002";
+    private static final String DEV3 = "of:0000000000000003";
+    private static final String DEV4 = "of:0000000000000004";
+    private static final String RANGE_14 = "1-4";
+    private static final String RANGE_79 = "7-9";
+    private static final String P1 = "1";
+    private static final String P5 = "5";
+    private static final String P9 = "9";
+
+    private BlockedPortsConfig cfg;
+    private BlockedPortsConfig.Range range;
+
+    private void print(String s) {
+        System.out.println(s);
+    }
+
+    private void print(Object o) {
+        print(o.toString());
+    }
+
+    @Before
+    public void setUp() throws IOException {
+        InputStream blockedPortsJson = BlockedPortsConfigTest.class
+                .getResourceAsStream("/blocked-ports.json");
+        JsonNode node = MAPPER.readTree(blockedPortsJson);
+        cfg = new BlockedPortsConfig();
+        cfg.init(APP_ID, KEY, node, MAPPER, null);
+    }
+
+    @Test
+    public void basic() {
+        cfg = new BlockedPortsConfig();
+        print(cfg);
+
+        assertEquals("non-empty devices list", 0, cfg.deviceIds().size());
+        assertEquals("non-empty port-ranges list", 0, cfg.portRanges("non-exist").size());
+    }
+
+
+    @Test
+    public void overIteratePort() {
+        Iterator<Long> iterator = cfg.portIterator(DEV3);
+        while (iterator.hasNext()) {
+            print(iterator.next());
+        }
+
+        try {
+            print(iterator.next());
+            fail("NoSuchElement exception NOT thrown");
+        } catch (NoSuchElementException e) {
+            print("<good> " + e);
+        }
+    }
+
+    @Test
+    public void overIterateRange() {
+        range = new BlockedPortsConfig.Range("4-6");
+
+        Iterator<Long> iterator = range.iterator();
+        while (iterator.hasNext()) {
+            print(iterator.next());
+        }
+
+        try {
+            print(iterator.next());
+            fail("NoSuchElement exception NOT thrown");
+        } catch (NoSuchElementException e) {
+            print("<good> " + e);
+        }
+    }
+
+
+    @Test
+    public void simple() {
+        List<String> devIds = cfg.deviceIds();
+        print(devIds);
+        assertEquals("wrong dev id count", 3, devIds.size());
+        assertEquals("missing dev 1", true, devIds.contains(DEV1));
+        assertEquals("dev 2??", false, devIds.contains(DEV2));
+        assertEquals("missing dev 3", true, devIds.contains(DEV3));
+
+        List<String> d1ranges = cfg.portRanges(DEV1);
+        print(d1ranges);
+        assertEquals("wrong d1 range count", 2, d1ranges.size());
+        assertEquals("missing 1-4", true, d1ranges.contains(RANGE_14));
+        assertEquals("missing 7-9", true, d1ranges.contains(RANGE_79));
+
+        List<String> d2ranges = cfg.portRanges(DEV2);
+        print(d2ranges);
+        assertEquals("wrong d2 range count", 0, d2ranges.size());
+
+        List<String> d3ranges = cfg.portRanges(DEV3);
+        print(d3ranges);
+        assertEquals("wrong d3 range count", 1, d3ranges.size());
+        assertEquals("range 1-4?", false, d3ranges.contains(RANGE_14));
+        assertEquals("missing 7-9", true, d3ranges.contains(RANGE_79));
+    }
+
+
+    private void verifyPorts(List<Long> ports, long... exp) {
+        assertEquals("Wrong port count", exp.length, ports.size());
+        for (long e : exp) {
+            assertEquals("missing port", true, ports.contains(e));
+        }
+    }
+
+    private void verifyPortIterator(String devid, long... exp) {
+        List<Long> ports = new ArrayList<>();
+        Iterator<Long> iter = cfg.portIterator(devid);
+        iter.forEachRemaining(ports::add);
+        print(ports);
+        verifyPorts(ports, exp);
+    }
+
+    @Test
+    public void rangeIterators() {
+        verifyPortIterator(DEV1, 1, 2, 3, 4, 7, 8, 9);
+        verifyPortIterator(DEV2);
+        verifyPortIterator(DEV3, 7, 8, 9);
+    }
+
+    @Test
+    public void singlePorts() {
+        List<String> devIds = cfg.deviceIds();
+        print(devIds);
+        assertEquals("wrong dev id count", 3, devIds.size());
+        assertEquals("missing dev 4", true, devIds.contains(DEV4));
+
+        List<String> d1ranges = cfg.portRanges(DEV4);
+        print(d1ranges);
+        assertEquals("wrong d4 range count", 3, d1ranges.size());
+        assertEquals("missing 1", true, d1ranges.contains(P1));
+        assertEquals("missing 5", true, d1ranges.contains(P5));
+        assertEquals("missing 9", true, d1ranges.contains(P9));
+
+        verifyPortIterator(DEV4, 1, 5, 9);
+    }
+
+
+    // test Range inner class
+
+    @Test
+    public void rangeBadFormat() {
+        try {
+            range = new BlockedPortsConfig.Range("not-a-range-format");
+            fail("no exception thrown");
+        } catch (IllegalArgumentException iar) {
+            print(iar);
+            assertEquals("wrong msg", "Bad Range Format not-a-range-format", iar.getMessage());
+        }
+    }
+
+    @Test
+    public void rangeBadHi() {
+        try {
+            range = new BlockedPortsConfig.Range("2-nine");
+            fail("no exception thrown");
+        } catch (IllegalArgumentException iar) {
+            print(iar);
+            assertEquals("wrong msg", "Bad Range Format 2-nine", iar.getMessage());
+        }
+    }
+
+    @Test
+    public void rangeHiLessThanLo() {
+        try {
+            range = new BlockedPortsConfig.Range("9-5");
+            fail("no exception thrown");
+        } catch (IllegalArgumentException iar) {
+            print(iar);
+            assertEquals("wrong msg", "Bad Range Format 9-5", iar.getMessage());
+        }
+    }
+
+    @Test
+    public void rangeNegative() {
+        try {
+            range = new BlockedPortsConfig.Range("-2-4");
+            fail("no exception thrown");
+        } catch (IllegalArgumentException iar) {
+            print(iar);
+            assertEquals("wrong msg", "Bad Range Format -2-4", iar.getMessage());
+        }
+    }
+
+    @Test
+    public void rangeGood() {
+        range = new BlockedPortsConfig.Range("100-104");
+        List<Long> values = new ArrayList<>();
+        range.iterator().forEachRemaining(values::add);
+        print(values);
+        verifyPorts(values, 100, 101, 102, 103, 104);
+    }
+}
diff --git a/apps/segmentrouting/src/test/resources/blocked-ports.json b/apps/segmentrouting/src/test/resources/blocked-ports.json
new file mode 100644
index 0000000..2543f3d
--- /dev/null
+++ b/apps/segmentrouting/src/test/resources/blocked-ports.json
@@ -0,0 +1,5 @@
+{
+  "of:0000000000000001": ["1-4", "7-9"],
+  "of:0000000000000003": ["7-9"],
+  "of:0000000000000004": ["1", "5", "9"]
+}