diff --git a/bpf_progs/netd.h b/bpf_progs/netd.h
index d1fc58d..64ed633 100644
--- a/bpf_progs/netd.h
+++ b/bpf_progs/netd.h
@@ -192,6 +192,7 @@
     OEM_DENY_1_MATCH = (1 << 9),
     OEM_DENY_2_MATCH = (1 << 10),
     OEM_DENY_3_MATCH = (1 << 11),
+    BACKGROUND_MATCH = (1 << 12)
 };
 // LINT.ThenChange(../framework/src/android/net/BpfNetMapsConstants.java)
 
@@ -244,7 +245,8 @@
 // DROP_IF_SET is set of rules that DROP if rule is globally enabled, and per-uid bit is set
 #define DROP_IF_SET (STANDBY_MATCH | OEM_DENY_1_MATCH | OEM_DENY_2_MATCH | OEM_DENY_3_MATCH)
 // DROP_IF_UNSET is set of rules that should DROP if globally enabled, and per-uid bit is NOT set
-#define DROP_IF_UNSET (DOZABLE_MATCH | POWERSAVE_MATCH | RESTRICTED_MATCH | LOW_POWER_STANDBY_MATCH)
+#define DROP_IF_UNSET (DOZABLE_MATCH | POWERSAVE_MATCH | RESTRICTED_MATCH \
+                        | LOW_POWER_STANDBY_MATCH | BACKGROUND_MATCH)
 
 // Warning: funky bit-wise arithmetic: in parallel, for all DROP_IF_SET/UNSET rules
 // check whether the rules are globally enabled, and if so whether the rules are
diff --git a/common/flags.aconfig b/common/flags.aconfig
index 0c46b48..b85c2fe 100644
--- a/common/flags.aconfig
+++ b/common/flags.aconfig
@@ -34,3 +34,10 @@
   description: "This flag controls whether isUidNetworkingBlocked is supported"
   bug: "297836825"
 }
+
+flag {
+  name: "basic_background_restrictions_enabled"
+  namespace: "android_core_networking"
+  description: "Block network access for apps in a low importance background state"
+  bug: "304347838"
+}
diff --git a/framework/api/module-lib-current.txt b/framework/api/module-lib-current.txt
index 4d55067..bfb4981 100644
--- a/framework/api/module-lib-current.txt
+++ b/framework/api/module-lib-current.txt
@@ -45,6 +45,7 @@
     field public static final int BLOCKED_METERED_REASON_DATA_SAVER = 65536; // 0x10000
     field public static final int BLOCKED_METERED_REASON_MASK = -65536; // 0xffff0000
     field public static final int BLOCKED_METERED_REASON_USER_RESTRICTED = 131072; // 0x20000
+    field @FlaggedApi("com.android.net.flags.basic_background_restrictions_enabled") public static final int BLOCKED_REASON_APP_BACKGROUND = 64; // 0x40
     field public static final int BLOCKED_REASON_APP_STANDBY = 4; // 0x4
     field public static final int BLOCKED_REASON_BATTERY_SAVER = 1; // 0x1
     field public static final int BLOCKED_REASON_DOZE = 2; // 0x2
@@ -52,6 +53,7 @@
     field public static final int BLOCKED_REASON_LOW_POWER_STANDBY = 32; // 0x20
     field public static final int BLOCKED_REASON_NONE = 0; // 0x0
     field public static final int BLOCKED_REASON_RESTRICTED_MODE = 8; // 0x8
+    field @FlaggedApi("com.android.net.flags.basic_background_restrictions_enabled") public static final int FIREWALL_CHAIN_BACKGROUND = 6; // 0x6
     field public static final int FIREWALL_CHAIN_DOZABLE = 1; // 0x1
     field public static final int FIREWALL_CHAIN_LOW_POWER_STANDBY = 5; // 0x5
     field public static final int FIREWALL_CHAIN_OEM_DENY_1 = 7; // 0x7
diff --git a/framework/src/android/net/BpfNetMapsConstants.java b/framework/src/android/net/BpfNetMapsConstants.java
index c784597..5d0fe73 100644
--- a/framework/src/android/net/BpfNetMapsConstants.java
+++ b/framework/src/android/net/BpfNetMapsConstants.java
@@ -16,6 +16,7 @@
 
 package android.net;
 
+import static android.net.ConnectivityManager.FIREWALL_CHAIN_BACKGROUND;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_DOZABLE;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_OEM_DENY_1;
@@ -77,6 +78,7 @@
     public static final long OEM_DENY_1_MATCH = (1 << 9);
     public static final long OEM_DENY_2_MATCH = (1 << 10);
     public static final long OEM_DENY_3_MATCH = (1 << 11);
+    public static final long BACKGROUND_MATCH = (1 << 12);
 
     public static final List<Pair<Long, String>> MATCH_LIST = Arrays.asList(
             Pair.create(HAPPY_BOX_MATCH, "HAPPY_BOX_MATCH"),
@@ -90,7 +92,8 @@
             Pair.create(LOCKDOWN_VPN_MATCH, "LOCKDOWN_VPN_MATCH"),
             Pair.create(OEM_DENY_1_MATCH, "OEM_DENY_1_MATCH"),
             Pair.create(OEM_DENY_2_MATCH, "OEM_DENY_2_MATCH"),
-            Pair.create(OEM_DENY_3_MATCH, "OEM_DENY_3_MATCH")
+            Pair.create(OEM_DENY_3_MATCH, "OEM_DENY_3_MATCH"),
+            Pair.create(BACKGROUND_MATCH, "BACKGROUND_MATCH")
     );
 
     /**
@@ -102,7 +105,8 @@
             FIREWALL_CHAIN_DOZABLE,
             FIREWALL_CHAIN_POWERSAVE,
             FIREWALL_CHAIN_RESTRICTED,
-            FIREWALL_CHAIN_LOW_POWER_STANDBY
+            FIREWALL_CHAIN_LOW_POWER_STANDBY,
+            FIREWALL_CHAIN_BACKGROUND
     );
 
     /**
diff --git a/framework/src/android/net/BpfNetMapsUtils.java b/framework/src/android/net/BpfNetMapsUtils.java
index e9c9137..11d610c 100644
--- a/framework/src/android/net/BpfNetMapsUtils.java
+++ b/framework/src/android/net/BpfNetMapsUtils.java
@@ -17,6 +17,7 @@
 package android.net;
 
 import static android.net.BpfNetMapsConstants.ALLOW_CHAINS;
+import static android.net.BpfNetMapsConstants.BACKGROUND_MATCH;
 import static android.net.BpfNetMapsConstants.DENY_CHAINS;
 import static android.net.BpfNetMapsConstants.DOZABLE_MATCH;
 import static android.net.BpfNetMapsConstants.LOW_POWER_STANDBY_MATCH;
@@ -28,6 +29,7 @@
 import static android.net.BpfNetMapsConstants.POWERSAVE_MATCH;
 import static android.net.BpfNetMapsConstants.RESTRICTED_MATCH;
 import static android.net.BpfNetMapsConstants.STANDBY_MATCH;
+import static android.net.ConnectivityManager.FIREWALL_CHAIN_BACKGROUND;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_DOZABLE;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_OEM_DENY_1;
@@ -70,6 +72,8 @@
                 return POWERSAVE_MATCH;
             case FIREWALL_CHAIN_RESTRICTED:
                 return RESTRICTED_MATCH;
+            case FIREWALL_CHAIN_BACKGROUND:
+                return BACKGROUND_MATCH;
             case FIREWALL_CHAIN_LOW_POWER_STANDBY:
                 return LOW_POWER_STANDBY_MATCH;
             case FIREWALL_CHAIN_OEM_DENY_1:
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 586e4b0..57ecf49 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -135,6 +135,8 @@
                 "com.android.net.flags.set_data_saver_via_cm";
         static final String SUPPORT_IS_UID_NETWORKING_BLOCKED =
                 "com.android.net.flags.support_is_uid_networking_blocked";
+        static final String BASIC_BACKGROUND_RESTRICTIONS_ENABLED =
+                "com.android.net.flags.basic_background_restrictions_enabled";
     }
 
     /**
@@ -908,6 +910,16 @@
     public static final int BLOCKED_REASON_LOW_POWER_STANDBY = 1 << 5;
 
     /**
+     * Flag to indicate that an app is subject to default background restrictions that would
+     * result in its network access being blocked.
+     *
+     * @hide
+     */
+    @FlaggedApi(Flags.BASIC_BACKGROUND_RESTRICTIONS_ENABLED)
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    public static final int BLOCKED_REASON_APP_BACKGROUND = 1 << 6;
+
+    /**
      * Flag to indicate that an app is subject to Data saver restrictions that would
      * result in its metered network access being blocked.
      *
@@ -946,6 +958,7 @@
             BLOCKED_REASON_RESTRICTED_MODE,
             BLOCKED_REASON_LOCKDOWN_VPN,
             BLOCKED_REASON_LOW_POWER_STANDBY,
+            BLOCKED_REASON_APP_BACKGROUND,
             BLOCKED_METERED_REASON_DATA_SAVER,
             BLOCKED_METERED_REASON_USER_RESTRICTED,
             BLOCKED_METERED_REASON_ADMIN_DISABLED,
@@ -1004,6 +1017,16 @@
     public static final int FIREWALL_CHAIN_LOW_POWER_STANDBY = 5;
 
     /**
+     * Firewall chain used for always-on default background restrictions.
+     * Allowlist of apps that have access because either they are in the foreground or they are
+     * exempted for specific situations while in the background.
+     * @hide
+     */
+    @FlaggedApi(Flags.BASIC_BACKGROUND_RESTRICTIONS_ENABLED)
+    @SystemApi(client = MODULE_LIBRARIES)
+    public static final int FIREWALL_CHAIN_BACKGROUND = 6;
+
+    /**
      * Firewall chain used for OEM-specific application restrictions.
      *
      * Denylist of apps that will not have network access due to OEM-specific restrictions. If an
@@ -1062,6 +1085,7 @@
         FIREWALL_CHAIN_POWERSAVE,
         FIREWALL_CHAIN_RESTRICTED,
         FIREWALL_CHAIN_LOW_POWER_STANDBY,
+        FIREWALL_CHAIN_BACKGROUND,
         FIREWALL_CHAIN_OEM_DENY_1,
         FIREWALL_CHAIN_OEM_DENY_2,
         FIREWALL_CHAIN_OEM_DENY_3
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index d8417c1..47e0bd9 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -12884,6 +12884,7 @@
             case ConnectivityManager.FIREWALL_CHAIN_POWERSAVE:
             case ConnectivityManager.FIREWALL_CHAIN_RESTRICTED:
             case ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY:
+            case ConnectivityManager.FIREWALL_CHAIN_BACKGROUND:
                 defaultRule = FIREWALL_RULE_DENY;
                 break;
             default:
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index 62614c1..0a143c5 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -38,6 +38,7 @@
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.ConnectivityManager.EXTRA_NETWORK;
 import static android.net.ConnectivityManager.EXTRA_NETWORK_REQUEST;
+import static android.net.ConnectivityManager.FIREWALL_CHAIN_BACKGROUND;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_DOZABLE;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_OEM_DENY_1;
@@ -3538,6 +3539,12 @@
         doTestFirewallBlocking(FIREWALL_CHAIN_DOZABLE, ALLOWLIST);
     }
 
+    @Test @IgnoreUpTo(Build.VERSION_CODES.UPSIDE_DOWN_CAKE) @ConnectivityModuleTest
+    @AppModeFull(reason = "Socket cannot bind in instant app mode")
+    public void testFirewallBlockingBackground() {
+        doTestFirewallBlocking(FIREWALL_CHAIN_BACKGROUND, ALLOWLIST);
+    }
+
     @Test @IgnoreUpTo(SC_V2) @ConnectivityModuleTest
     @AppModeFull(reason = "Socket cannot bind in instant app mode")
     public void testFirewallBlockingPowersave() {
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index aae37e5..bafd450 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -59,6 +59,7 @@
 import static android.net.ConnectivityManager.EXTRA_NETWORK_INFO;
 import static android.net.ConnectivityManager.EXTRA_NETWORK_TYPE;
 import static android.net.ConnectivityManager.EXTRA_REALTIME_NS;
+import static android.net.ConnectivityManager.FIREWALL_CHAIN_BACKGROUND;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_DOZABLE;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_OEM_DENY_1;
@@ -10475,6 +10476,7 @@
         doTestSetUidFirewallRule(FIREWALL_CHAIN_POWERSAVE, FIREWALL_RULE_DENY);
         doTestSetUidFirewallRule(FIREWALL_CHAIN_RESTRICTED, FIREWALL_RULE_DENY);
         doTestSetUidFirewallRule(FIREWALL_CHAIN_LOW_POWER_STANDBY, FIREWALL_RULE_DENY);
+        doTestSetUidFirewallRule(FIREWALL_CHAIN_BACKGROUND, FIREWALL_RULE_DENY);
         doTestSetUidFirewallRule(FIREWALL_CHAIN_OEM_DENY_1, FIREWALL_RULE_ALLOW);
         doTestSetUidFirewallRule(FIREWALL_CHAIN_OEM_DENY_2, FIREWALL_RULE_ALLOW);
         doTestSetUidFirewallRule(FIREWALL_CHAIN_OEM_DENY_3, FIREWALL_RULE_ALLOW);
@@ -10488,6 +10490,7 @@
                 FIREWALL_CHAIN_POWERSAVE,
                 FIREWALL_CHAIN_RESTRICTED,
                 FIREWALL_CHAIN_LOW_POWER_STANDBY,
+                FIREWALL_CHAIN_BACKGROUND,
                 FIREWALL_CHAIN_OEM_DENY_1,
                 FIREWALL_CHAIN_OEM_DENY_2,
                 FIREWALL_CHAIN_OEM_DENY_3);
@@ -10537,6 +10540,7 @@
         doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_POWERSAVE, allowlist);
         doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_RESTRICTED, allowlist);
         doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_LOW_POWER_STANDBY, allowlist);
+        doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_BACKGROUND, allowlist);
 
         doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_STANDBY, denylist);
         doTestSetFirewallChainEnabledCloseSocket(FIREWALL_CHAIN_OEM_DENY_1, denylist);
@@ -10558,6 +10562,7 @@
         doTestReplaceFirewallChain(FIREWALL_CHAIN_POWERSAVE);
         doTestReplaceFirewallChain(FIREWALL_CHAIN_RESTRICTED);
         doTestReplaceFirewallChain(FIREWALL_CHAIN_LOW_POWER_STANDBY);
+        doTestReplaceFirewallChain(FIREWALL_CHAIN_BACKGROUND);
         doTestReplaceFirewallChain(FIREWALL_CHAIN_OEM_DENY_1);
         doTestReplaceFirewallChain(FIREWALL_CHAIN_OEM_DENY_2);
         doTestReplaceFirewallChain(FIREWALL_CHAIN_OEM_DENY_3);