Add DHCP to the list of allowed open ports for Tethering

Bug: 229948900
Test: m -j cts
      cts-tradefed
      run cts -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.ListeningPortsTest#testNoRemotelyAccessibleListeningUdpPorts
Change-Id: I2182248612716170ff1b314a418df5ffe2dc0117
diff --git a/hostsidetests/appsecurity/test-apps/ListeningPortsApp/src/android/appsecurity/cts/listeningports/ListeningPortsTest.java b/hostsidetests/appsecurity/test-apps/ListeningPortsApp/src/android/appsecurity/cts/listeningports/ListeningPortsTest.java
index 8deeb76..12fbb3c 100644
--- a/hostsidetests/appsecurity/test-apps/ListeningPortsApp/src/android/appsecurity/cts/listeningports/ListeningPortsTest.java
+++ b/hostsidetests/appsecurity/test-apps/ListeningPortsApp/src/android/appsecurity/cts/listeningports/ListeningPortsTest.java
@@ -73,6 +73,7 @@
         EXCEPTION_PATTERNS.add(":: 1002");          // used by remote control
         EXCEPTION_PATTERNS.add(":: 1020");          // used by remote control
         EXCEPTION_PATTERNS.add("0.0.0.0:7275");     // used by supl
+        EXCEPTION_PATTERNS.add("0.0.0.0:68");       // DHCP server for Tethering
         // b/150186547 ports
         EXCEPTION_PATTERNS.add("192.168.17.10:48881");
         EXCEPTION_PATTERNS.add("192.168.17.10:48896");