diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index 73175580..742fd02 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_defaults {
     name: "TetheringAndroidLibraryDefaults",
     sdk_version: "module_current",
@@ -29,8 +33,7 @@
         "androidx.annotation_annotation",
         "modules-utils-build",
         "netlink-client",
-        // TODO: use networkstack-client instead of just including the AIDL interface
-        "networkstack-aidl-interfaces-unstable-java",
+        "networkstack-client",
         "android.hardware.tetheroffload.config-V1.0-java",
         "android.hardware.tetheroffload.control-V1.0-java",
         "net-utils-framework-common",
@@ -145,3 +148,10 @@
     apex_available: ["com.android.tethering"],
     min_sdk_version: "30",
 }
+
+sdk {
+    name: "tethering-module-sdk",
+    java_sdk_libs: [
+        "framework-tethering",
+    ],
+}
diff --git a/Tethering/apex/Android.bp b/Tethering/apex/Android.bp
index 7970944..e9deeff 100644
--- a/Tethering/apex/Android.bp
+++ b/Tethering/apex/Android.bp
@@ -14,11 +14,15 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 apex {
     name: "com.android.tethering",
     // TODO: make updatable again once this contains only updatable artifacts (in particular, this
     // cannot build as updatable unless service-connectivity builds against stable API).
-    // updatable: true,
+    updatable: false,
     // min_sdk_version: "30",
     java_libs: [
         "framework-tethering",
diff --git a/Tethering/bpf_progs/Android.bp b/Tethering/bpf_progs/Android.bp
index b06528b..2b10f89 100644
--- a/Tethering/bpf_progs/Android.bp
+++ b/Tethering/bpf_progs/Android.bp
@@ -17,6 +17,10 @@
 //
 // struct definitions shared with JNI
 //
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 cc_library_headers {
     name: "bpf_tethering_headers",
     vendor_available: false,
diff --git a/Tethering/bpf_progs/bpf_tethering.h b/Tethering/bpf_progs/bpf_tethering.h
index c8ada88..efda228 100644
--- a/Tethering/bpf_progs/bpf_tethering.h
+++ b/Tethering/bpf_progs/bpf_tethering.h
@@ -16,6 +16,11 @@
 
 #pragma once
 
+#include <linux/if.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+
 // Common definitions for BPF code in the tethering mainline module.
 // These definitions are available to:
 // - The BPF programs in Tethering/bpf_progs/
@@ -40,8 +45,11 @@
     ERR(IS_IP_FRAG)          \
     ERR(CHECKSUM)            \
     ERR(NON_TCP_UDP)         \
+    ERR(NON_TCP)             \
+    ERR(SHORT_L4_HEADER)     \
     ERR(SHORT_TCP_HEADER)    \
     ERR(SHORT_UDP_HEADER)    \
+    ERR(UDP_CSUM_ZERO)       \
     ERR(TRUNCATED_IPV4)      \
     ERR(_MAX)
 
@@ -56,3 +64,151 @@
     BPF_TETHER_ERRORS
 };
 #undef ERR
+
+// This header file is shared by eBPF kernel programs (C) and netd (C++) and
+// some of the maps are also accessed directly from Java mainline module code.
+//
+// Hence: explicitly pad all relevant structures and assert that their size
+// is the sum of the sizes of their fields.
+#define STRUCT_SIZE(name, size) _Static_assert(sizeof(name) == (size), "Incorrect struct size.")
+
+
+#define BPF_PATH_TETHER BPF_PATH "tethering/"
+
+#define TETHER_STATS_MAP_PATH BPF_PATH_TETHER "map_offload_tether_stats_map"
+
+typedef uint32_t TetherStatsKey;  // upstream ifindex
+
+typedef struct {
+    uint64_t rxPackets;
+    uint64_t rxBytes;
+    uint64_t rxErrors;
+    uint64_t txPackets;
+    uint64_t txBytes;
+    uint64_t txErrors;
+} TetherStatsValue;
+STRUCT_SIZE(TetherStatsValue, 6 * 8);  // 48
+
+#define TETHER_LIMIT_MAP_PATH BPF_PATH_TETHER "map_offload_tether_limit_map"
+
+typedef uint32_t TetherLimitKey;    // upstream ifindex
+typedef uint64_t TetherLimitValue;  // in bytes
+
+#define TETHER_DOWNSTREAM6_TC_PROG_RAWIP_NAME "prog_offload_schedcls_tether_downstream6_rawip"
+#define TETHER_DOWNSTREAM6_TC_PROG_ETHER_NAME "prog_offload_schedcls_tether_downstream6_ether"
+
+#define TETHER_DOWNSTREAM6_TC_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM6_TC_PROG_RAWIP_NAME
+#define TETHER_DOWNSTREAM6_TC_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM6_TC_PROG_ETHER_NAME
+
+#define TETHER_DOWNSTREAM6_MAP_PATH BPF_PATH_TETHER "map_offload_tether_downstream6_map"
+
+// For now tethering offload only needs to support downstreams that use 6-byte MAC addresses,
+// because all downstream types that are currently supported (WiFi, USB, Bluetooth and
+// Ethernet) have 6-byte MAC addresses.
+
+typedef struct {
+    uint32_t iif;            // The input interface index
+                             // TODO: extend this to include dstMac
+    struct in6_addr neigh6;  // The destination IPv6 address
+} TetherDownstream6Key;
+STRUCT_SIZE(TetherDownstream6Key, 4 + 16);  // 20
+
+typedef struct {
+    uint32_t oif;             // The output interface to redirect to
+    struct ethhdr macHeader;  // includes dst/src mac and ethertype (zeroed iff rawip egress)
+    uint16_t pmtu;            // The maximum L3 output path/route mtu
+} Tether6Value;
+STRUCT_SIZE(Tether6Value, 4 + 14 + 2);  // 20
+
+#define TETHER_DOWNSTREAM64_MAP_PATH BPF_PATH_TETHER "map_offload_tether_downstream64_map"
+
+typedef struct {
+    uint32_t iif;              // The input interface index
+    uint8_t dstMac[ETH_ALEN];  // destination ethernet mac address (zeroed iff rawip ingress)
+    uint16_t l4Proto;          // IPPROTO_TCP/UDP/...
+    struct in6_addr src6;      // source &
+    struct in6_addr dst6;      // destination IPv6 addresses
+    __be16 srcPort;            // source &
+    __be16 dstPort;            // destination tcp/udp/... ports
+} TetherDownstream64Key;
+STRUCT_SIZE(TetherDownstream64Key, 4 + 6 + 2 + 16 + 16 + 2 + 2);  // 48
+
+typedef struct {
+    uint32_t oif;             // The output interface to redirect to
+    struct ethhdr macHeader;  // includes dst/src mac and ethertype (zeroed iff rawip egress)
+    uint16_t pmtu;            // The maximum L3 output path/route mtu
+    struct in_addr src4;      // source &
+    struct in_addr dst4;      // destination IPv4 addresses
+    __be16 srcPort;           // source &
+    __be16 outPort;           // destination tcp/udp/... ports
+    uint64_t lastUsed;        // Kernel updates on each use with bpf_ktime_get_boot_ns()
+} TetherDownstream64Value;
+STRUCT_SIZE(TetherDownstream64Value, 4 + 14 + 2 + 4 + 4 + 2 + 2 + 8);  // 40
+
+#define TETHER_UPSTREAM6_TC_PROG_RAWIP_NAME "prog_offload_schedcls_tether_upstream6_rawip"
+#define TETHER_UPSTREAM6_TC_PROG_ETHER_NAME "prog_offload_schedcls_tether_upstream6_ether"
+
+#define TETHER_UPSTREAM6_TC_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_UPSTREAM6_TC_PROG_RAWIP_NAME
+#define TETHER_UPSTREAM6_TC_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_UPSTREAM6_TC_PROG_ETHER_NAME
+
+#define TETHER_UPSTREAM6_MAP_PATH BPF_PATH_TETHER "map_offload_tether_upstream6_map"
+
+typedef struct {
+    uint32_t iif;  // The input interface index
+                   // TODO: extend this to include dstMac and src ip /64 subnet
+} TetherUpstream6Key;
+STRUCT_SIZE(TetherUpstream6Key, 4);
+
+#define TETHER_DOWNSTREAM4_TC_PROG_RAWIP_NAME "prog_offload_schedcls_tether_downstream4_rawip"
+#define TETHER_DOWNSTREAM4_TC_PROG_ETHER_NAME "prog_offload_schedcls_tether_downstream4_ether"
+
+#define TETHER_DOWNSTREAM4_TC_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM4_TC_PROG_RAWIP_NAME
+#define TETHER_DOWNSTREAM4_TC_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM4_TC_PROG_ETHER_NAME
+
+#define TETHER_DOWNSTREAM4_MAP_PATH BPF_PATH_TETHER "map_offload_tether_downstream4_map"
+
+
+#define TETHER_UPSTREAM4_TC_PROG_RAWIP_NAME "prog_offload_schedcls_tether_upstream4_rawip"
+#define TETHER_UPSTREAM4_TC_PROG_ETHER_NAME "prog_offload_schedcls_tether_upstream4_ether"
+
+#define TETHER_UPSTREAM4_TC_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_UPSTREAM4_TC_PROG_RAWIP_NAME
+#define TETHER_UPSTREAM4_TC_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_UPSTREAM4_TC_PROG_ETHER_NAME
+
+#define TETHER_UPSTREAM4_MAP_PATH BPF_PATH_TETHER "map_offload_tether_upstream4_map"
+
+typedef struct {
+    uint32_t iif;              // The input interface index
+    uint8_t dstMac[ETH_ALEN];  // destination ethernet mac address (zeroed iff rawip ingress)
+    uint16_t l4Proto;          // IPPROTO_TCP/UDP/...
+    struct in_addr src4;       // source &
+    struct in_addr dst4;       // destination IPv4 addresses
+    __be16 srcPort;            // source &
+    __be16 dstPort;            // destination TCP/UDP/... ports
+} Tether4Key;
+STRUCT_SIZE(Tether4Key, 4 + 6 + 2 + 4 + 4 + 2 + 2);  // 24
+
+typedef struct {
+    uint32_t oif;             // The output interface to redirect to
+    struct ethhdr macHeader;  // includes dst/src mac and ethertype (zeroed iff rawip egress)
+    uint16_t pmtu;            // Maximum L3 output path/route mtu
+    struct in6_addr src46;    // source &                 (always IPv4 mapped for downstream)
+    struct in6_addr dst46;    // destination IP addresses (may be IPv4 mapped or IPv6 for upstream)
+    __be16 srcPort;           // source &
+    __be16 dstPort;           // destination tcp/udp/... ports
+    uint64_t last_used;       // Kernel updates on each use with bpf_ktime_get_boot_ns()
+} Tether4Value;
+STRUCT_SIZE(Tether4Value, 4 + 14 + 2 + 16 + 16 + 2 + 2 + 8);  // 64
+
+#define TETHER_DOWNSTREAM_XDP_PROG_RAWIP_NAME "prog_offload_xdp_tether_downstream_rawip"
+#define TETHER_DOWNSTREAM_XDP_PROG_ETHER_NAME "prog_offload_xdp_tether_downstream_ether"
+
+#define TETHER_DOWNSTREAM_XDP_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM_XDP_PROG_RAWIP_NAME
+#define TETHER_DOWNSTREAM_XDP_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_DOWNSTREAM_XDP_PROG_ETHER_NAME
+
+#define TETHER_UPSTREAM_XDP_PROG_RAWIP_NAME "prog_offload_xdp_tether_upstream_rawip"
+#define TETHER_UPSTREAM_XDP_PROG_ETHER_NAME "prog_offload_xdp_tether_upstream_ether"
+
+#define TETHER_UPSTREAM_XDP_PROG_RAWIP_PATH BPF_PATH_TETHER TETHER_UPSTREAM_XDP_PROG_RAWIP_NAME
+#define TETHER_UPSTREAM_XDP_PROG_ETHER_PATH BPF_PATH_TETHER TETHER_UPSTREAM_XDP_PROG_ETHER_NAME
+
+#undef STRUCT_SIZE
diff --git a/Tethering/bpf_progs/offload.c b/Tethering/bpf_progs/offload.c
index bf60e67..ea64343 100644
--- a/Tethering/bpf_progs/offload.c
+++ b/Tethering/bpf_progs/offload.c
@@ -27,7 +27,6 @@
 #include "bpf_helpers.h"
 #include "bpf_net_helpers.h"
 #include "bpf_tethering.h"
-#include "netdbpf/bpf_shared.h"
 
 // From kernel:include/net/ip.h
 #define IP_DF 0x4000  // Flag: "Don't Fragment"
@@ -68,7 +67,25 @@
 #define ETH_IP6_TCP_OFFSET(field) (ETH_HLEN + IP6_TCP_OFFSET(field))
 #define ETH_IP6_UDP_OFFSET(field) (ETH_HLEN + IP6_UDP_OFFSET(field))
 
-// ----- Tethering stats and data limits -----
+// ----- Tethering Error Counters -----
+
+DEFINE_BPF_MAP_GRW(tether_error_map, ARRAY, uint32_t, uint32_t, BPF_TETHER_ERR__MAX,
+                   AID_NETWORK_STACK)
+
+#define COUNT_AND_RETURN(counter, ret) do {                  \
+    uint32_t code = BPF_TETHER_ERR_ ## counter;                 \
+    uint32_t *count = bpf_tether_error_map_lookup_elem(&code);  \
+    if (count) __sync_fetch_and_add(count, 1);               \
+    return ret;                                              \
+} while(0)
+
+#define TC_DROP(counter) COUNT_AND_RETURN(counter, TC_ACT_SHOT)
+#define TC_PUNT(counter) COUNT_AND_RETURN(counter, TC_ACT_OK)
+
+#define XDP_DROP(counter) COUNT_AND_RETURN(counter, XDP_DROP)
+#define XDP_PUNT(counter) COUNT_AND_RETURN(counter, XDP_PASS)
+
+// ----- Tethering Data Stats and Limits -----
 
 // Tethering stats, indexed by upstream interface.
 DEFINE_BPF_MAP_GRW(tether_stats_map, HASH, TetherStatsKey, TetherStatsValue, 16, AID_NETWORK_STACK)
@@ -83,24 +100,11 @@
                    AID_NETWORK_STACK)
 
 DEFINE_BPF_MAP_GRW(tether_downstream64_map, HASH, TetherDownstream64Key, TetherDownstream64Value,
-                   64, AID_NETWORK_STACK)
+                   1024, AID_NETWORK_STACK)
 
 DEFINE_BPF_MAP_GRW(tether_upstream6_map, HASH, TetherUpstream6Key, Tether6Value, 64,
                    AID_NETWORK_STACK)
 
-DEFINE_BPF_MAP_GRW(tether_error_map, ARRAY, __u32, __u32, BPF_TETHER_ERR__MAX,
-                   AID_NETWORK_STACK)
-
-#define COUNT_AND_RETURN(counter, ret) do {                    \
-    __u32 code = BPF_TETHER_ERR_ ## counter;                 \
-    __u32 *count = bpf_tether_error_map_lookup_elem(&code);  \
-    if (count) __sync_fetch_and_add(count, 1);               \
-    return ret;                                              \
-} while(0)
-
-#define DROP(counter) COUNT_AND_RETURN(counter, TC_ACT_SHOT)
-#define PUNT(counter) COUNT_AND_RETURN(counter, TC_ACT_OK)
-
 static inline __always_inline int do_forward6(struct __sk_buff* skb, const bool is_ethernet,
         const bool downstream) {
     const int l2_header_size = is_ethernet ? sizeof(struct ethhdr) : 0;
@@ -122,11 +126,11 @@
     if (is_ethernet && (eth->h_proto != htons(ETH_P_IPV6))) return TC_ACT_OK;
 
     // IP version must be 6
-    if (ip6->version != 6) PUNT(INVALID_IP_VERSION);
+    if (ip6->version != 6) TC_PUNT(INVALID_IP_VERSION);
 
     // Cannot decrement during forward if already zero or would be zero,
     // Let the kernel's stack handle these cases and generate appropriate ICMP errors.
-    if (ip6->hop_limit <= 1) PUNT(LOW_TTL);
+    if (ip6->hop_limit <= 1) TC_PUNT(LOW_TTL);
 
     // If hardware offload is running and programming flows based on conntrack entries,
     // try not to interfere with it.
@@ -135,27 +139,27 @@
 
         // Make sure we can get at the tcp header
         if (data + l2_header_size + sizeof(*ip6) + sizeof(*tcph) > data_end)
-            PUNT(INVALID_TCP_HEADER);
+            TC_PUNT(INVALID_TCP_HEADER);
 
         // Do not offload TCP packets with any one of the SYN/FIN/RST flags
-        if (tcph->syn || tcph->fin || tcph->rst) PUNT(TCP_CONTROL_PACKET);
+        if (tcph->syn || tcph->fin || tcph->rst) TC_PUNT(TCP_CONTROL_PACKET);
     }
 
     // Protect against forwarding packets sourced from ::1 or fe80::/64 or other weirdness.
     __be32 src32 = ip6->saddr.s6_addr32[0];
     if (src32 != htonl(0x0064ff9b) &&                        // 64:ff9b:/32 incl. XLAT464 WKP
         (src32 & htonl(0xe0000000)) != htonl(0x20000000))    // 2000::/3 Global Unicast
-        PUNT(NON_GLOBAL_SRC);
+        TC_PUNT(NON_GLOBAL_SRC);
 
     // Protect against forwarding packets destined to ::1 or fe80::/64 or other weirdness.
     __be32 dst32 = ip6->daddr.s6_addr32[0];
     if (dst32 != htonl(0x0064ff9b) &&                        // 64:ff9b:/32 incl. XLAT464 WKP
         (dst32 & htonl(0xe0000000)) != htonl(0x20000000))    // 2000::/3 Global Unicast
-        PUNT(NON_GLOBAL_DST);
+        TC_PUNT(NON_GLOBAL_DST);
 
     // In the upstream direction do not forward traffic within the same /64 subnet.
     if (!downstream && (src32 == dst32) && (ip6->saddr.s6_addr32[1] == ip6->daddr.s6_addr32[1]))
-        PUNT(LOCAL_SRC_DST);
+        TC_PUNT(LOCAL_SRC_DST);
 
     TetherDownstream6Key kd = {
             .iif = skb->ifindex,
@@ -177,15 +181,15 @@
     TetherStatsValue* stat_v = bpf_tether_stats_map_lookup_elem(&stat_and_limit_k);
 
     // If we don't have anywhere to put stats, then abort...
-    if (!stat_v) PUNT(NO_STATS_ENTRY);
+    if (!stat_v) TC_PUNT(NO_STATS_ENTRY);
 
     uint64_t* limit_v = bpf_tether_limit_map_lookup_elem(&stat_and_limit_k);
 
     // If we don't have a limit, then abort...
-    if (!limit_v) PUNT(NO_LIMIT_ENTRY);
+    if (!limit_v) TC_PUNT(NO_LIMIT_ENTRY);
 
     // Required IPv6 minimum mtu is 1280, below that not clear what we should do, abort...
-    if (v->pmtu < IPV6_MIN_MTU) PUNT(BELOW_IPV6_MTU);
+    if (v->pmtu < IPV6_MIN_MTU) TC_PUNT(BELOW_IPV6_MTU);
 
     // Approximate handling of TCP/IPv6 overhead for incoming LRO/GRO packets: default
     // outbound path mtu of 1500 is not necessarily correct, but worst case we simply
@@ -210,7 +214,7 @@
     // a packet we let the core stack deal with things.
     // (The core stack needs to handle limits correctly anyway,
     // since we don't offload all traffic in both directions)
-    if (stat_v->rxBytes + stat_v->txBytes + bytes > *limit_v) PUNT(LIMIT_REACHED);
+    if (stat_v->rxBytes + stat_v->txBytes + bytes > *limit_v) TC_PUNT(LIMIT_REACHED);
 
     if (!is_ethernet) {
         // Try to inject an ethernet header, and simply return if we fail.
@@ -218,7 +222,7 @@
         // because this is easier and the kernel will strip extraneous ethernet header.
         if (bpf_skb_change_head(skb, sizeof(struct ethhdr), /*flags*/ 0)) {
             __sync_fetch_and_add(downstream ? &stat_v->rxErrors : &stat_v->txErrors, 1);
-            PUNT(CHANGE_HEAD_FAILED);
+            TC_PUNT(CHANGE_HEAD_FAILED);
         }
 
         // bpf_skb_change_head() invalidates all pointers - reload them
@@ -230,7 +234,7 @@
         // I do not believe this can ever happen, but keep the verifier happy...
         if (data + sizeof(struct ethhdr) + sizeof(*ip6) > data_end) {
             __sync_fetch_and_add(downstream ? &stat_v->rxErrors : &stat_v->txErrors, 1);
-            DROP(TOO_SHORT);
+            TC_DROP(TOO_SHORT);
         }
     };
 
@@ -336,12 +340,12 @@
 
 // ----- IPv4 Support -----
 
-DEFINE_BPF_MAP_GRW(tether_downstream4_map, HASH, Tether4Key, Tether4Value, 64, AID_NETWORK_STACK)
+DEFINE_BPF_MAP_GRW(tether_downstream4_map, HASH, Tether4Key, Tether4Value, 1024, AID_NETWORK_STACK)
 
-DEFINE_BPF_MAP_GRW(tether_upstream4_map, HASH, Tether4Key, Tether4Value, 64, AID_NETWORK_STACK)
+DEFINE_BPF_MAP_GRW(tether_upstream4_map, HASH, Tether4Key, Tether4Value, 1024, AID_NETWORK_STACK)
 
 static inline __always_inline int do_forward4(struct __sk_buff* skb, const bool is_ethernet,
-        const bool downstream) {
+        const bool downstream, const bool updatetime) {
     const int l2_header_size = is_ethernet ? sizeof(struct ethhdr) : 0;
     void* data = (void*)(long)skb->data;
     const void* data_end = (void*)(long)skb->data_end;
@@ -361,10 +365,10 @@
     if (is_ethernet && (eth->h_proto != htons(ETH_P_IP))) return TC_ACT_OK;
 
     // IP version must be 4
-    if (ip->version != 4) PUNT(INVALID_IP_VERSION);
+    if (ip->version != 4) TC_PUNT(INVALID_IP_VERSION);
 
     // We cannot handle IP options, just standard 20 byte == 5 dword minimal IPv4 header
-    if (ip->ihl != 5) PUNT(HAS_IP_OPTIONS);
+    if (ip->ihl != 5) TC_PUNT(HAS_IP_OPTIONS);
 
     // Calculate the IPv4 one's complement checksum of the IPv4 header.
     __wsum sum4 = 0;
@@ -375,36 +379,91 @@
     sum4 = (sum4 & 0xFFFF) + (sum4 >> 16);  // collapse u32 into range 1 .. 0x1FFFE
     sum4 = (sum4 & 0xFFFF) + (sum4 >> 16);  // collapse any potential carry into u16
     // for a correct checksum we should get *a* zero, but sum4 must be positive, ie 0xFFFF
-    if (sum4 != 0xFFFF) PUNT(CHECKSUM);
+    if (sum4 != 0xFFFF) TC_PUNT(CHECKSUM);
 
     // Minimum IPv4 total length is the size of the header
-    if (ntohs(ip->tot_len) < sizeof(*ip)) PUNT(TRUNCATED_IPV4);
+    if (ntohs(ip->tot_len) < sizeof(*ip)) TC_PUNT(TRUNCATED_IPV4);
 
     // We are incapable of dealing with IPv4 fragments
-    if (ip->frag_off & ~htons(IP_DF)) PUNT(IS_IP_FRAG);
+    if (ip->frag_off & ~htons(IP_DF)) TC_PUNT(IS_IP_FRAG);
 
     // Cannot decrement during forward if already zero or would be zero,
     // Let the kernel's stack handle these cases and generate appropriate ICMP errors.
-    if (ip->ttl <= 1) PUNT(LOW_TTL);
+    if (ip->ttl <= 1) TC_PUNT(LOW_TTL);
 
-    const bool is_tcp = (ip->protocol == IPPROTO_TCP);
+    // If we cannot update the 'last_used' field due to lack of bpf_ktime_get_boot_ns() helper,
+    // then it is not safe to offload UDP due to the small conntrack timeouts, as such,
+    // in such a situation we can only support TCP.  This also has the added nice benefit of
+    // using a separate error counter, and thus making it obvious which version of the program
+    // is loaded.
+    if (!updatetime && ip->protocol != IPPROTO_TCP) TC_PUNT(NON_TCP);
 
-    // We do not support anything besides TCP and UDP
-    if (!is_tcp && (ip->protocol != IPPROTO_UDP)) PUNT(NON_TCP_UDP);
+    // We do not support offloading anything besides IPv4 TCP and UDP, due to need for NAT,
+    // but no need to check this if !updatetime due to check immediately above.
+    if (updatetime && (ip->protocol != IPPROTO_TCP) && (ip->protocol != IPPROTO_UDP))
+        TC_PUNT(NON_TCP_UDP);
+
+    // We want to make sure that the compiler will, in the !updatetime case, entirely optimize
+    // out all the non-tcp logic.  Also note that at this point is_udp === !is_tcp.
+    const bool is_tcp = !updatetime || (ip->protocol == IPPROTO_TCP);
+
+    // This is a bit of a hack to make things easier on the bpf verifier.
+    // (In particular I believe the Linux 4.14 kernel's verifier can get confused later on about
+    // what offsets into the packet are valid and can spuriously reject the program, this is
+    // because it fails to realize that is_tcp && !is_tcp is impossible)
+    //
+    // For both TCP & UDP we'll need to read and modify the src/dst ports, which so happen to
+    // always be in the first 4 bytes of the L4 header.  Additionally for UDP we'll need access
+    // to the checksum field which is in bytes 7 and 8.  While for TCP we'll need to read the
+    // TCP flags (at offset 13) and access to the checksum field (2 bytes at offset 16).
+    // As such we *always* need access to at least 8 bytes.
+    if (data + l2_header_size + sizeof(*ip) + 8 > data_end) TC_PUNT(SHORT_L4_HEADER);
 
     struct tcphdr* tcph = is_tcp ? (void*)(ip + 1) : NULL;
     struct udphdr* udph = is_tcp ? NULL : (void*)(ip + 1);
 
     if (is_tcp) {
         // Make sure we can get at the tcp header
-        if (data + l2_header_size + sizeof(*ip) + sizeof(*tcph) > data_end) PUNT(SHORT_TCP_HEADER);
+        if (data + l2_header_size + sizeof(*ip) + sizeof(*tcph) > data_end)
+            TC_PUNT(SHORT_TCP_HEADER);
 
         // If hardware offload is running and programming flows based on conntrack entries, try not
         // to interfere with it, so do not offload TCP packets with any one of the SYN/FIN/RST flags
-        if (tcph->syn || tcph->fin || tcph->rst) PUNT(TCP_CONTROL_PACKET);
+        if (tcph->syn || tcph->fin || tcph->rst) TC_PUNT(TCP_CONTROL_PACKET);
     } else { // UDP
         // Make sure we can get at the udp header
-        if (data + l2_header_size + sizeof(*ip) + sizeof(*udph) > data_end) PUNT(SHORT_UDP_HEADER);
+        if (data + l2_header_size + sizeof(*ip) + sizeof(*udph) > data_end)
+            TC_PUNT(SHORT_UDP_HEADER);
+
+        // Skip handling of CHECKSUM_COMPLETE packets with udp checksum zero due to need for
+        // additional updating of skb->csum (this could be fixed up manually with more effort).
+        //
+        // Note that the in-kernel implementation of 'int64_t bpf_csum_update(skb, u32 csum)' is:
+        //   if (skb->ip_summed == CHECKSUM_COMPLETE)
+        //     return (skb->csum = csum_add(skb->csum, csum));
+        //   else
+        //     return -ENOTSUPP;
+        //
+        // So this will punt any CHECKSUM_COMPLETE packet with a zero UDP checksum,
+        // and leave all other packets unaffected (since it just at most adds zero to skb->csum).
+        //
+        // In practice this should almost never trigger because most nics do not generate
+        // CHECKSUM_COMPLETE packets on receive - especially so for nics/drivers on a phone.
+        //
+        // Additionally since we're forwarding, in most cases the value of the skb->csum field
+        // shouldn't matter (it's not used by physical nic egress).
+        //
+        // It only matters if we're ingressing through a CHECKSUM_COMPLETE capable nic
+        // and egressing through a virtual interface looping back to the kernel itself
+        // (ie. something like veth) where the CHECKSUM_COMPLETE/skb->csum can get reused
+        // on ingress.
+        //
+        // If we were in the kernel we'd simply probably call
+        //   void skb_checksum_complete_unset(struct sk_buff *skb) {
+        //     if (skb->ip_summed == CHECKSUM_COMPLETE) skb->ip_summed = CHECKSUM_NONE;
+        //   }
+        // here instead.  Perhaps there should be a bpf helper for that?
+        if (!udph->check && (bpf_csum_update(skb, 0) >= 0)) TC_PUNT(UDP_CSUM_ZERO);
     }
 
     Tether4Key k = {
@@ -428,15 +487,15 @@
     TetherStatsValue* stat_v = bpf_tether_stats_map_lookup_elem(&stat_and_limit_k);
 
     // If we don't have anywhere to put stats, then abort...
-    if (!stat_v) PUNT(NO_STATS_ENTRY);
+    if (!stat_v) TC_PUNT(NO_STATS_ENTRY);
 
     uint64_t* limit_v = bpf_tether_limit_map_lookup_elem(&stat_and_limit_k);
 
     // If we don't have a limit, then abort...
-    if (!limit_v) PUNT(NO_LIMIT_ENTRY);
+    if (!limit_v) TC_PUNT(NO_LIMIT_ENTRY);
 
     // Required IPv4 minimum mtu is 68, below that not clear what we should do, abort...
-    if (v->pmtu < 68) PUNT(BELOW_IPV4_MTU);
+    if (v->pmtu < 68) TC_PUNT(BELOW_IPV4_MTU);
 
     // Approximate handling of TCP/IPv4 overhead for incoming LRO/GRO packets: default
     // outbound path mtu of 1500 is not necessarily correct, but worst case we simply
@@ -461,10 +520,7 @@
     // a packet we let the core stack deal with things.
     // (The core stack needs to handle limits correctly anyway,
     // since we don't offload all traffic in both directions)
-    if (stat_v->rxBytes + stat_v->txBytes + bytes > *limit_v) PUNT(LIMIT_REACHED);
-
-
-if (!is_tcp) return TC_ACT_OK; // HACK
+    if (stat_v->rxBytes + stat_v->txBytes + bytes > *limit_v) TC_PUNT(LIMIT_REACHED);
 
     if (!is_ethernet) {
         // Try to inject an ethernet header, and simply return if we fail.
@@ -472,7 +528,7 @@
         // because this is easier and the kernel will strip extraneous ethernet header.
         if (bpf_skb_change_head(skb, sizeof(struct ethhdr), /*flags*/ 0)) {
             __sync_fetch_and_add(downstream ? &stat_v->rxErrors : &stat_v->txErrors, 1);
-            PUNT(CHANGE_HEAD_FAILED);
+            TC_PUNT(CHANGE_HEAD_FAILED);
         }
 
         // bpf_skb_change_head() invalidates all pointers - reload them
@@ -486,7 +542,7 @@
         // I do not believe this can ever happen, but keep the verifier happy...
         if (data + sizeof(struct ethhdr) + sizeof(*ip) + (is_tcp ? sizeof(*tcph) : sizeof(*udph)) > data_end) {
             __sync_fetch_and_add(downstream ? &stat_v->rxErrors : &stat_v->txErrors, 1);
-            DROP(TOO_SHORT);
+            TC_DROP(TOO_SHORT);
         }
     };
 
@@ -498,30 +554,39 @@
     // For a rawip tx interface it will simply be a bunch of zeroes and later stripped.
     *eth = v->macHeader;
 
+    const int l4_offs_csum = is_tcp ? ETH_IP4_TCP_OFFSET(check) : ETH_IP4_UDP_OFFSET(check);
     const int sz4 = sizeof(__be32);
+    // UDP 0 is special and stored as FFFF (this flag also causes a csum of 0 to be unmodified)
+    const int l4_flags = is_tcp ? 0 : BPF_F_MARK_MANGLED_0;
     const __be32 old_daddr = k.dst4.s_addr;
     const __be32 old_saddr = k.src4.s_addr;
     const __be32 new_daddr = v->dst46.s6_addr32[3];
     const __be32 new_saddr = v->src46.s6_addr32[3];
 
-    bpf_l4_csum_replace(skb, ETH_IP4_TCP_OFFSET(check), old_daddr, new_daddr, sz4 | BPF_F_PSEUDO_HDR);
+    bpf_l4_csum_replace(skb, l4_offs_csum, old_daddr, new_daddr, sz4 | BPF_F_PSEUDO_HDR | l4_flags);
     bpf_l3_csum_replace(skb, ETH_IP4_OFFSET(check), old_daddr, new_daddr, sz4);
     bpf_skb_store_bytes(skb, ETH_IP4_OFFSET(daddr), &new_daddr, sz4, 0);
 
-    bpf_l4_csum_replace(skb, ETH_IP4_TCP_OFFSET(check), old_saddr, new_saddr, sz4 | BPF_F_PSEUDO_HDR);
+    bpf_l4_csum_replace(skb, l4_offs_csum, old_saddr, new_saddr, sz4 | BPF_F_PSEUDO_HDR | l4_flags);
     bpf_l3_csum_replace(skb, ETH_IP4_OFFSET(check), old_saddr, new_saddr, sz4);
     bpf_skb_store_bytes(skb, ETH_IP4_OFFSET(saddr), &new_saddr, sz4, 0);
 
     const int sz2 = sizeof(__be16);
-    bpf_l4_csum_replace(skb, ETH_IP4_TCP_OFFSET(check), k.srcPort, v->srcPort, sz2);
-    bpf_skb_store_bytes(skb, ETH_IP4_TCP_OFFSET(source), &v->srcPort, sz2, 0);
+    // The offsets for TCP and UDP ports: source (u16 @ L4 offset 0) & dest (u16 @ L4 offset 2) are
+    // actually the same, so the compiler should just optimize them both down to a constant.
+    bpf_l4_csum_replace(skb, l4_offs_csum, k.srcPort, v->srcPort, sz2 | l4_flags);
+    bpf_skb_store_bytes(skb, is_tcp ? ETH_IP4_TCP_OFFSET(source) : ETH_IP4_UDP_OFFSET(source),
+                        &v->srcPort, sz2, 0);
 
-    bpf_l4_csum_replace(skb, ETH_IP4_TCP_OFFSET(check), k.dstPort, v->dstPort, sz2);
-    bpf_skb_store_bytes(skb, ETH_IP4_TCP_OFFSET(dest), &v->dstPort, sz2, 0);
+    bpf_l4_csum_replace(skb, l4_offs_csum, k.dstPort, v->dstPort, sz2 | l4_flags);
+    bpf_skb_store_bytes(skb, is_tcp ? ETH_IP4_TCP_OFFSET(dest) : ETH_IP4_UDP_OFFSET(dest),
+                        &v->dstPort, sz2, 0);
 
-// TTL dec
+    // TEMP HACK: lack of TTL decrement
 
-// v->last_used = bpf_ktime_get_boot_ns();
+    // This requires the bpf_ktime_get_boot_ns() helper which was added in 5.8,
+    // and backported to all Android Common Kernel 4.14+ trees.
+    if (updatetime) v->last_used = bpf_ktime_get_boot_ns();
 
     __sync_fetch_and_add(downstream ? &stat_v->rxPackets : &stat_v->txPackets, packets);
     __sync_fetch_and_add(downstream ? &stat_v->rxBytes : &stat_v->txBytes, bytes);
@@ -535,54 +600,123 @@
     return bpf_redirect(v->oif, 0 /* this is effectively BPF_F_EGRESS */);
 }
 
-// Real implementations for 5.9+ kernels
+// Full featured (required) implementations for 5.8+ kernels
 
-DEFINE_BPF_PROG_KVER("schedcls/tether_downstream4_ether$5_9", AID_ROOT, AID_NETWORK_STACK,
-                     sched_cls_tether_downstream4_ether_5_9, KVER(5, 9, 0))
+DEFINE_BPF_PROG_KVER("schedcls/tether_downstream4_ether$5_8", AID_ROOT, AID_NETWORK_STACK,
+                     sched_cls_tether_downstream4_ether_5_8, KVER(5, 8, 0))
 (struct __sk_buff* skb) {
-    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ true);
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ true, /* updatetime */ true);
 }
 
-DEFINE_BPF_PROG_KVER("schedcls/tether_downstream4_rawip$5_9", AID_ROOT, AID_NETWORK_STACK,
-                     sched_cls_tether_downstream4_rawip_5_9, KVER(5, 9, 0))
+DEFINE_BPF_PROG_KVER("schedcls/tether_downstream4_rawip$5_8", AID_ROOT, AID_NETWORK_STACK,
+                     sched_cls_tether_downstream4_rawip_5_8, KVER(5, 8, 0))
 (struct __sk_buff* skb) {
-    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ true);
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ true, /* updatetime */ true);
 }
 
-DEFINE_BPF_PROG_KVER("schedcls/tether_upstream4_ether$5_9", AID_ROOT, AID_NETWORK_STACK,
-                     sched_cls_tether_upstream4_ether_5_9, KVER(5, 9, 0))
+DEFINE_BPF_PROG_KVER("schedcls/tether_upstream4_ether$5_8", AID_ROOT, AID_NETWORK_STACK,
+                     sched_cls_tether_upstream4_ether_5_8, KVER(5, 8, 0))
 (struct __sk_buff* skb) {
-    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ false);
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ false, /* updatetime */ true);
 }
 
-DEFINE_BPF_PROG_KVER("schedcls/tether_upstream4_rawip$5_9", AID_ROOT, AID_NETWORK_STACK,
-                     sched_cls_tether_upstream4_rawip_5_9, KVER(5, 9, 0))
+DEFINE_BPF_PROG_KVER("schedcls/tether_upstream4_rawip$5_8", AID_ROOT, AID_NETWORK_STACK,
+                     sched_cls_tether_upstream4_rawip_5_8, KVER(5, 8, 0))
 (struct __sk_buff* skb) {
-    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ false);
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ false, /* updatetime */ true);
 }
 
-// Placeholder implementations for older pre-5.9 kernels
+// Full featured (optional) implementations for [4.14..5.8) kernels
+
+DEFINE_OPTIONAL_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_ether$opt",
+                                    AID_ROOT, AID_NETWORK_STACK,
+                                    sched_cls_tether_downstream4_ether_opt,
+                                    KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ true, /* updatetime */ true);
+}
+
+DEFINE_OPTIONAL_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_rawip$opt",
+                                    AID_ROOT, AID_NETWORK_STACK,
+                                    sched_cls_tether_downstream4_rawip_opt,
+                                    KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ true, /* updatetime */ true);
+}
+
+DEFINE_OPTIONAL_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_ether$opt",
+                                    AID_ROOT, AID_NETWORK_STACK,
+                                    sched_cls_tether_upstream4_ether_opt,
+                                    KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ false, /* updatetime */ true);
+}
+
+DEFINE_OPTIONAL_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_rawip$opt",
+                                    AID_ROOT, AID_NETWORK_STACK,
+                                    sched_cls_tether_upstream4_rawip_opt,
+                                    KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ false, /* updatetime */ true);
+}
+
+// Partial (TCP-only: will not update 'last_used' field) implementations for 4.14+ kernels.
+// These will be loaded only if the above optional ones failed (loading of *these* must succeed).
+//
+// [Note: as a result TCP connections will not have their conntrack timeout refreshed, however,
+// since /proc/sys/net/netfilter/nf_conntrack_tcp_timeout_established defaults to 432000 (seconds),
+// this in practice means they'll break only after 5 days.  This seems an acceptable trade-off.
+//
+// Additionally kernel/tests change "net-test: add bpf_ktime_get_ns / bpf_ktime_get_boot_ns tests"
+// which enforces and documents the required kernel cherrypicks will make it pretty unlikely that
+// many devices upgrading to S will end up relying on these fallback programs.
+
+DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_ether$4_14", AID_ROOT, AID_NETWORK_STACK,
+                           sched_cls_tether_downstream4_ether_4_14, KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ true, /* updatetime */ false);
+}
+
+DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_rawip$4_14", AID_ROOT, AID_NETWORK_STACK,
+                           sched_cls_tether_downstream4_rawip_4_14, KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ true, /* updatetime */ false);
+}
+
+DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_ether$4_14", AID_ROOT, AID_NETWORK_STACK,
+                           sched_cls_tether_upstream4_ether_4_14, KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ true, /* downstream */ false, /* updatetime */ false);
+}
+
+DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_rawip$4_14", AID_ROOT, AID_NETWORK_STACK,
+                           sched_cls_tether_upstream4_rawip_4_14, KVER(4, 14, 0), KVER(5, 8, 0))
+(struct __sk_buff* skb) {
+    return do_forward4(skb, /* is_ethernet */ false, /* downstream */ false, /* updatetime */ false);
+}
+
+// Placeholder (no-op) implementations for older pre-4.14 kernels
 
 DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_ether$stub", AID_ROOT, AID_NETWORK_STACK,
-                           sched_cls_tether_downstream4_ether_stub, KVER_NONE, KVER(5, 9, 0))
+                           sched_cls_tether_downstream4_ether_stub, KVER_NONE, KVER(4, 14, 0))
 (struct __sk_buff* skb) {
     return TC_ACT_OK;
 }
 
 DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_downstream4_rawip$stub", AID_ROOT, AID_NETWORK_STACK,
-                           sched_cls_tether_downstream4_rawip_stub, KVER_NONE, KVER(5, 9, 0))
+                           sched_cls_tether_downstream4_rawip_stub, KVER_NONE, KVER(4, 14, 0))
 (struct __sk_buff* skb) {
     return TC_ACT_OK;
 }
 
 DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_ether$stub", AID_ROOT, AID_NETWORK_STACK,
-                           sched_cls_tether_upstream4_ether_stub, KVER_NONE, KVER(5, 9, 0))
+                           sched_cls_tether_upstream4_ether_stub, KVER_NONE, KVER(4, 14, 0))
 (struct __sk_buff* skb) {
     return TC_ACT_OK;
 }
 
 DEFINE_BPF_PROG_KVER_RANGE("schedcls/tether_upstream4_rawip$stub", AID_ROOT, AID_NETWORK_STACK,
-                           sched_cls_tether_upstream4_rawip_stub, KVER_NONE, KVER(5, 9, 0))
+                           sched_cls_tether_upstream4_rawip_stub, KVER_NONE, KVER(4, 14, 0))
 (struct __sk_buff* skb) {
     return TC_ACT_OK;
 }
@@ -613,4 +747,4 @@
 }
 
 LICENSE("Apache 2.0");
-CRITICAL("netd");
+CRITICAL("tethering");
diff --git a/Tethering/bpf_progs/test.c b/Tethering/bpf_progs/test.c
index c4a8271..3f0df2e 100644
--- a/Tethering/bpf_progs/test.c
+++ b/Tethering/bpf_progs/test.c
@@ -20,7 +20,7 @@
 
 #include "bpf_helpers.h"
 #include "bpf_net_helpers.h"
-#include "netdbpf/bpf_shared.h"
+#include "bpf_tethering.h"
 
 // Used only by TetheringPrivilegedTests, not by production code.
 DEFINE_BPF_MAP_GRW(tether_downstream6_map, HASH, TetherDownstream6Key, Tether6Value, 16,
diff --git a/Tethering/common/TetheringLib/Android.bp b/Tethering/common/TetheringLib/Android.bp
index a10729d..2631d08 100644
--- a/Tethering/common/TetheringLib/Android.bp
+++ b/Tethering/common/TetheringLib/Android.bp
@@ -13,6 +13,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_sdk_library {
     name: "framework-tethering",
     defaults: ["framework-module-defaults"],
diff --git a/Tethering/src/com/android/networkstack/tethering/BpfMap.java b/Tethering/src/com/android/networkstack/tethering/BpfMap.java
index 9a9376f..e9b4ccf 100644
--- a/Tethering/src/com/android/networkstack/tethering/BpfMap.java
+++ b/Tethering/src/com/android/networkstack/tethering/BpfMap.java
@@ -226,6 +226,20 @@
         closeMap(mMapFd);
     }
 
+    /**
+     * Clears the map. The map may already be empty.
+     *
+     * @throws ErrnoException if the map is already closed, if an error occurred during iteration,
+     *                        or if a non-ENOENT error occurred when deleting a key.
+     */
+    public void clear() throws ErrnoException {
+        K key = getFirstKey();
+        while (key != null) {
+            deleteEntry(key);  // ignores ENOENT.
+            key = getFirstKey();
+        }
+    }
+
     private static native int closeMap(int fd) throws ErrnoException;
 
     private native int bpfFdGet(String path, int mode) throws ErrnoException, NullPointerException;
diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 385c691..ac5857d 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -1689,12 +1689,14 @@
             // If this is a Wi-Fi interface, tell WifiManager of any errors
             // or the inactive serving state.
             if (who.interfaceType() == TETHERING_WIFI) {
-                if (who.lastError() != TETHER_ERROR_NO_ERROR) {
-                    getWifiManager().updateInterfaceIpState(
-                            who.interfaceName(), IFACE_IP_MODE_CONFIGURATION_ERROR);
+                final WifiManager mgr = getWifiManager();
+                final String iface = who.interfaceName();
+                if (mgr == null) {
+                    Log.wtf(TAG, "Skipping WifiManager notification about inactive tethering");
+                } else if (who.lastError() != TETHER_ERROR_NO_ERROR) {
+                    mgr.updateInterfaceIpState(iface, IFACE_IP_MODE_CONFIGURATION_ERROR);
                 } else {
-                    getWifiManager().updateInterfaceIpState(
-                            who.interfaceName(), IFACE_IP_MODE_UNSPECIFIED);
+                    mgr.updateInterfaceIpState(iface, IFACE_IP_MODE_UNSPECIFIED);
                 }
             }
         }
@@ -2421,6 +2423,19 @@
             mLog.log(iface + " is not a tetherable iface, ignoring");
             return;
         }
+
+        final PackageManager pm = mContext.getPackageManager();
+        if ((interfaceType == TETHERING_WIFI || interfaceType == TETHERING_WIGIG)
+                && !pm.hasSystemFeature(PackageManager.FEATURE_WIFI)) {
+            mLog.log(iface + " is not tetherable, because WiFi feature is disabled");
+            return;
+        }
+        if (interfaceType == TETHERING_WIFI_P2P
+                && !pm.hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)) {
+            mLog.log(iface + " is not tetherable, because WiFi Direct feature is disabled");
+            return;
+        }
+
         maybeTrackNewInterfaceLocked(iface, interfaceType);
     }
 
diff --git a/Tethering/tests/Android.bp b/Tethering/tests/Android.bp
index 731144c..8f31c57 100644
--- a/Tethering/tests/Android.bp
+++ b/Tethering/tests/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 filegroup {
     name: "TetheringTestsJarJarRules",
     srcs: ["jarjar-rules.txt"],
diff --git a/Tethering/tests/integration/Android.bp b/Tethering/tests/integration/Android.bp
index f456273..f63df2c 100644
--- a/Tethering/tests/integration/Android.bp
+++ b/Tethering/tests/integration/Android.bp
@@ -13,6 +13,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_defaults {
     name: "TetheringIntegrationTestsDefaults",
     srcs: [
diff --git a/Tethering/tests/mts/Android.bp b/Tethering/tests/mts/Android.bp
index f925b0a..20a5f18 100644
--- a/Tethering/tests/mts/Android.bp
+++ b/Tethering/tests/mts/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test {
     // This tests for functionality that is not required for devices that
     // don't use Tethering mainline module.
diff --git a/Tethering/tests/privileged/Android.bp b/Tethering/tests/privileged/Android.bp
index 9217345..75fdd6e 100644
--- a/Tethering/tests/privileged/Android.bp
+++ b/Tethering/tests/privileged/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_defaults {
     name: "TetheringPrivilegedTestsJniDefaults",
     jni_libs: [
diff --git a/Tethering/tests/privileged/src/com/android/networkstack/tethering/BpfMapTest.java b/Tethering/tests/privileged/src/com/android/networkstack/tethering/BpfMapTest.java
index cceaa8c..62302c3 100644
--- a/Tethering/tests/privileged/src/com/android/networkstack/tethering/BpfMapTest.java
+++ b/Tethering/tests/privileged/src/com/android/networkstack/tethering/BpfMapTest.java
@@ -312,6 +312,32 @@
     }
 
     @Test
+    public void testClear() throws Exception {
+        // Clear an empty map.
+        assertTrue(mTestMap.isEmpty());
+        mTestMap.clear();
+
+        // Clear a map with some data in it.
+        final ArrayMap<TetherDownstream6Key, Tether6Value> resultMap =
+                new ArrayMap<>(mTestData);
+        for (int i = 0; i < resultMap.size(); i++) {
+            mTestMap.insertEntry(resultMap.keyAt(i), resultMap.valueAt(i));
+        }
+        assertFalse(mTestMap.isEmpty());
+        mTestMap.clear();
+        assertTrue(mTestMap.isEmpty());
+
+        // Clearing an already-closed map throws.
+        mTestMap.close();
+        try {
+            mTestMap.clear();
+            fail("clearing already-closed map should throw");
+        } catch (ErrnoException expected) {
+            assertEquals(OsConstants.EBADF, expected.errno);
+        }
+    }
+
+    @Test
     public void testInsertOverflow() throws Exception {
         final ArrayMap<TetherDownstream6Key, Tether6Value> testData =
                 new ArrayMap<>();
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index 6c479a0..d469b37 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -15,6 +15,10 @@
 //
 
 // Tests in this folder are included both in unit tests and CTS.
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_library {
     name: "TetheringCommonTests",
     srcs: [
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 4b69456..c5a43b7 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -591,6 +591,9 @@
                 ArgumentCaptor.forClass(SoftApCallback.class);
         verify(mWifiManager).registerSoftApCallback(any(), softApCallbackCaptor.capture());
         mSoftApCallback = softApCallbackCaptor.getValue();
+
+        when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_WIFI)).thenReturn(true);
+        when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)).thenReturn(true);
     }
 
     private void setTetheringSupported(final boolean supported) {
diff --git a/tests/cts/hostside/Android.bp b/tests/cts/hostside/Android.bp
index 47b114b..3185f7e 100644
--- a/tests/cts/hostside/Android.bp
+++ b/tests/cts/hostside/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_test_host {
     name: "CtsHostsideNetworkTests",
     defaults: ["cts_defaults"],
diff --git a/tests/cts/hostside/TEST_MAPPING b/tests/cts/hostside/TEST_MAPPING
new file mode 100644
index 0000000..02d2d6e
--- /dev/null
+++ b/tests/cts/hostside/TEST_MAPPING
@@ -0,0 +1,18 @@
+{
+  "presubmit": [
+    {
+      "name": "CtsHostsideNetworkTests",
+      "options": [
+        {
+          "include-filter": "com.android.cts.net.HostsideRestrictBackgroundNetworkTests"
+        },
+        {
+          "exclude-annotation": "androidx.test.filters.FlakyTest"
+        },
+        {
+          "exclude-annotation": "android.platform.test.annotations.FlakyTest"
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/cts/hostside/aidl/Android.bp b/tests/cts/hostside/aidl/Android.bp
index 320a1fa..2751f6f 100644
--- a/tests/cts/hostside/aidl/Android.bp
+++ b/tests/cts/hostside/aidl/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_test_helper_library {
     name: "CtsHostsideNetworkTestsAidl",
     sdk_version: "current",
diff --git a/tests/cts/hostside/app/Android.bp b/tests/cts/hostside/app/Android.bp
index 9903756..813e6c7 100644
--- a/tests/cts/hostside/app/Android.bp
+++ b/tests/cts/hostside/app/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test_helper_app {
     name: "CtsHostsideNetworkTestsApp",
     defaults: ["cts_support_defaults"],
diff --git a/tests/cts/hostside/app2/Android.bp b/tests/cts/hostside/app2/Android.bp
index 8e27931..b448459 100644
--- a/tests/cts/hostside/app2/Android.bp
+++ b/tests/cts/hostside/app2/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test_helper_app {
     name: "CtsHostsideNetworkTestsApp2",
     defaults: ["cts_support_defaults"],
diff --git a/tests/cts/hostside/certs/Android.bp b/tests/cts/hostside/certs/Android.bp
index ab4cf34..60b5476 100644
--- a/tests/cts/hostside/certs/Android.bp
+++ b/tests/cts/hostside/certs/Android.bp
@@ -1,3 +1,7 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_app_certificate {
     name: "cts-net-app",
     certificate: "cts-net-app",
diff --git a/tests/cts/net/Android.bp b/tests/cts/net/Android.bp
index 528171a..bbfb2c1 100644
--- a/tests/cts/net/Android.bp
+++ b/tests/cts/net/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_defaults {
     name: "CtsNetTestCasesDefaults",
     defaults: ["cts_defaults"],
@@ -37,6 +41,7 @@
     ],
     jarjar_rules: "jarjar-rules-shared.txt",
     static_libs: [
+        "bouncycastle-unbundled",
         "FrameworksNetCommonTests",
         "TestNetworkStackLib",
         "core-tests-support",
@@ -44,6 +49,7 @@
         "ctstestrunner-axt",
         "junit",
         "junit-params",
+        "modules-utils-build",
         "net-utils-framework-common",
         "truth-prebuilt",
     ],
diff --git a/tests/cts/net/api23Test/Android.bp b/tests/cts/net/api23Test/Android.bp
index e43a5e8..5b37294 100644
--- a/tests/cts/net/api23Test/Android.bp
+++ b/tests/cts/net/api23Test/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test {
     name: "CtsNetApi23TestCases",
     defaults: ["cts_defaults"],
diff --git a/tests/cts/net/appForApi23/Android.bp b/tests/cts/net/appForApi23/Android.bp
index cec6d7f..b39690f 100644
--- a/tests/cts/net/appForApi23/Android.bp
+++ b/tests/cts/net/appForApi23/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test {
     name: "CtsNetTestAppForApi23",
     defaults: ["cts_defaults"],
diff --git a/tests/cts/net/jni/Android.bp b/tests/cts/net/jni/Android.bp
index 3953aeb..13f38d7 100644
--- a/tests/cts/net/jni/Android.bp
+++ b/tests/cts/net/jni/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 cc_library_shared {
     name: "libnativedns_jni",
 
diff --git a/tests/cts/net/native/dns/Android.bp b/tests/cts/net/native/dns/Android.bp
index 6defd35..1bc5a86 100644
--- a/tests/cts/net/native/dns/Android.bp
+++ b/tests/cts/net/native/dns/Android.bp
@@ -1,3 +1,7 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 cc_defaults {
     name: "dns_async_defaults",
 
diff --git a/tests/cts/net/native/qtaguid/Android.bp b/tests/cts/net/native/qtaguid/Android.bp
index 4861651..68bb14d 100644
--- a/tests/cts/net/native/qtaguid/Android.bp
+++ b/tests/cts/net/native/qtaguid/Android.bp
@@ -14,6 +14,10 @@
 
 // Build the unit tests.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 cc_test {
     name: "CtsNativeNetTestCases",
 
diff --git a/tests/cts/net/src/android/net/cts/CaptivePortalTest.kt b/tests/cts/net/src/android/net/cts/CaptivePortalTest.kt
index eb5048f..a889c41 100644
--- a/tests/cts/net/src/android/net/cts/CaptivePortalTest.kt
+++ b/tests/cts/net/src/android/net/cts/CaptivePortalTest.kt
@@ -26,6 +26,9 @@
 import android.net.Network
 import android.net.NetworkCapabilities
 import android.net.NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL
+import android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET
+import android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED
+import android.net.NetworkCapabilities.TRANSPORT_CELLULAR
 import android.net.NetworkCapabilities.TRANSPORT_WIFI
 import android.net.NetworkRequest
 import android.net.Uri
@@ -44,8 +47,10 @@
 import android.text.TextUtils
 import androidx.test.platform.app.InstrumentationRegistry.getInstrumentation
 import androidx.test.runner.AndroidJUnit4
+import com.android.testutils.RecorderCallback
 import com.android.testutils.TestHttpServer
 import com.android.testutils.TestHttpServer.Request
+import com.android.testutils.TestableNetworkCallback
 import com.android.testutils.isDevSdkInRange
 import com.android.testutils.runAsShell
 import fi.iki.elonen.NanoHTTPD.Response.Status
@@ -124,7 +129,20 @@
         assumeTrue(pm.hasSystemFeature(FEATURE_TELEPHONY))
         assumeTrue(pm.hasSystemFeature(FEATURE_WIFI))
         utils.ensureWifiConnected()
-        utils.connectToCell()
+        val cellNetwork = utils.connectToCell()
+
+        // Verify cell network is validated
+        val cellReq = NetworkRequest.Builder()
+                .addTransportType(TRANSPORT_CELLULAR)
+                .addCapability(NET_CAPABILITY_INTERNET)
+                .build()
+        val cellCb = TestableNetworkCallback(timeoutMs = TEST_TIMEOUT_MS)
+        cm.registerNetworkCallback(cellReq, cellCb)
+        val cb = cellCb.eventuallyExpectOrNull<RecorderCallback.CallbackEntry.CapabilitiesChanged> {
+            it.network == cellNetwork && it.caps.hasCapability(NET_CAPABILITY_VALIDATED)
+        }
+        assertNotNull(cb, "Mobile network $cellNetwork has no access to the internet. " +
+                "Check the mobile data connection.")
 
         // Have network validation use a local server that serves a HTTPS error / HTTP redirect
         server.addResponse(Request(TEST_PORTAL_URL_PATH), Status.OK,
@@ -135,7 +153,8 @@
         setHttpsUrlDeviceConfig(makeUrl(TEST_HTTPS_URL_PATH))
         setHttpUrlDeviceConfig(makeUrl(TEST_HTTP_URL_PATH))
         // URL expiration needs to be in the next 10 minutes
-        setUrlExpirationDeviceConfig(System.currentTimeMillis() + TimeUnit.MINUTES.toMillis(9))
+        assertTrue(WIFI_CONNECT_TIMEOUT_MS < TimeUnit.MINUTES.toMillis(10))
+        setUrlExpirationDeviceConfig(System.currentTimeMillis() + WIFI_CONNECT_TIMEOUT_MS)
 
         // Wait for a captive portal to be detected on the network
         val wifiNetworkFuture = CompletableFuture<Network>()
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index 831810c..fad688b 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -109,6 +109,9 @@
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.internal.util.ArrayUtils;
+import com.android.modules.utils.build.SdkLevel;
+import com.android.testutils.DevSdkIgnoreRule;
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
 import com.android.testutils.RecorderCallback.CallbackEntry;
 import com.android.testutils.SkipPresubmit;
 import com.android.testutils.TestableNetworkCallback;
@@ -119,6 +122,7 @@
 
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -151,6 +155,8 @@
 
 @RunWith(AndroidJUnit4.class)
 public class ConnectivityManagerTest {
+    @Rule
+    public final DevSdkIgnoreRule ignoreRule = new DevSdkIgnoreRule();
 
     private static final String TAG = ConnectivityManagerTest.class.getSimpleName();
 
@@ -163,9 +169,7 @@
     private static final int MAX_KEEPALIVE_RETRY_COUNT = 3;
     private static final int MIN_KEEPALIVE_INTERVAL = 10;
 
-    // Changing meteredness on wifi involves reconnecting, which can take several seconds (involves
-    // re-associating, DHCP...)
-    private static final int NETWORK_CHANGE_METEREDNESS_TIMEOUT = 30_000;
+    private static final int NETWORK_CALLBACK_TIMEOUT_MS = 30_000;
     private static final int NUM_TRIES_MULTIPATH_PREF_CHECK = 20;
     private static final long INTERVAL_MULTIPATH_PREF_CHECK_MS = 500;
     // device could have only one interface: data, wifi.
@@ -518,11 +522,12 @@
         mCm.registerDefaultNetworkCallback(defaultTrackingCallback);
 
         final TestNetworkCallback systemDefaultTrackingCallback = new TestNetworkCallback();
-        runWithShellPermissionIdentity(() ->
-                mCm.registerSystemDefaultNetworkCallback(systemDefaultTrackingCallback,
-                        new Handler(Looper.getMainLooper())),
-                NETWORK_SETTINGS);
-
+        if (SdkLevel.isAtLeastS()) {
+            runWithShellPermissionIdentity(() ->
+                    mCm.registerSystemDefaultNetworkCallback(systemDefaultTrackingCallback,
+                            new Handler(Looper.getMainLooper())),
+                    NETWORK_SETTINGS);
+        }
 
         Network wifiNetwork = null;
 
@@ -539,16 +544,20 @@
             assertNotNull("Did not receive onAvailable on default network callback",
                     defaultTrackingCallback.waitForAvailable());
 
-            assertNotNull("Did not receive onAvailable on system default network callback",
-                    systemDefaultTrackingCallback.waitForAvailable());
+            if (SdkLevel.isAtLeastS()) {
+                assertNotNull("Did not receive onAvailable on system default network callback",
+                        systemDefaultTrackingCallback.waitForAvailable());
+            }
         } catch (InterruptedException e) {
             fail("Broadcast receiver or NetworkCallback wait was interrupted.");
         } finally {
             mCm.unregisterNetworkCallback(callback);
             mCm.unregisterNetworkCallback(defaultTrackingCallback);
-            runWithShellPermissionIdentity(
-                    () -> mCm.unregisterNetworkCallback(systemDefaultTrackingCallback),
-                    NETWORK_SETTINGS);
+            if (SdkLevel.isAtLeastS()) {
+                runWithShellPermissionIdentity(
+                        () -> mCm.unregisterNetworkCallback(systemDefaultTrackingCallback),
+                        NETWORK_SETTINGS);
+            }
         }
     }
 
@@ -567,17 +576,23 @@
 
         // Create a ConnectivityActionReceiver that has an IntentFilter for our locally defined
         // action, NETWORK_CALLBACK_ACTION.
-        IntentFilter filter = new IntentFilter();
+        final IntentFilter filter = new IntentFilter();
         filter.addAction(NETWORK_CALLBACK_ACTION);
 
-        ConnectivityActionReceiver receiver = new ConnectivityActionReceiver(
+        final ConnectivityActionReceiver receiver = new ConnectivityActionReceiver(
                 mCm, ConnectivityManager.TYPE_WIFI, NetworkInfo.State.CONNECTED);
         mContext.registerReceiver(receiver, filter);
 
         // Create a broadcast PendingIntent for NETWORK_CALLBACK_ACTION.
-        Intent intent = new Intent(NETWORK_CALLBACK_ACTION);
-        PendingIntent pendingIntent = PendingIntent.getBroadcast(
-                mContext, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);
+        final Intent intent = new Intent(NETWORK_CALLBACK_ACTION)
+                .setPackage(mContext.getPackageName());
+        // While ConnectivityService would put extra info such as network or request id before
+        // broadcasting the inner intent. The MUTABLE flag needs to be added accordingly.
+        // TODO: replace with PendingIntent.FLAG_MUTABLE when this code compiles against S+ or
+        //  shims.
+        final int pendingIntentFlagMutable = 1 << 25;
+        final PendingIntent pendingIntent = PendingIntent.getBroadcast(mContext, 0 /*requestCode*/,
+                intent, PendingIntent.FLAG_CANCEL_CURRENT | pendingIntentFlagMutable);
 
         // We will register for a WIFI network being available or lost.
         mCm.registerNetworkCallback(makeWifiNetworkRequest(), pendingIntent);
@@ -746,7 +761,9 @@
         // with the current setting. Therefore, if the setting has already been changed,
         // this method will return right away, and if not it will wait for the setting to change.
         mCm.registerDefaultNetworkCallback(networkCallback);
-        if (!latch.await(NETWORK_CHANGE_METEREDNESS_TIMEOUT, TimeUnit.MILLISECONDS)) {
+        // Changing meteredness on wifi involves reconnecting, which can take several seconds
+        // (involves re-associating, DHCP...).
+        if (!latch.await(NETWORK_CALLBACK_TIMEOUT_MS, TimeUnit.MILLISECONDS)) {
             fail("Timed out waiting for active network metered status to change to "
                  + requestedMeteredness + " ; network = " + mCm.getActiveNetwork());
         }
@@ -1499,12 +1516,12 @@
     }
 
     private void waitForAvailable(@NonNull final TestableNetworkCallback cb) {
-        cb.eventuallyExpect(CallbackEntry.AVAILABLE, AIRPLANE_MODE_CHANGE_TIMEOUT_MS,
+        cb.eventuallyExpect(CallbackEntry.AVAILABLE, NETWORK_CALLBACK_TIMEOUT_MS,
                 c -> c instanceof CallbackEntry.Available);
     }
 
     private void waitForLost(@NonNull final TestableNetworkCallback cb) {
-        cb.eventuallyExpect(CallbackEntry.LOST, AIRPLANE_MODE_CHANGE_TIMEOUT_MS,
+        cb.eventuallyExpect(CallbackEntry.LOST, NETWORK_CALLBACK_TIMEOUT_MS,
                 c -> c instanceof CallbackEntry.Lost);
     }
 
@@ -1556,16 +1573,17 @@
      * Verify background request can only be requested when acquiring
      * {@link android.Manifest.permission.NETWORK_SETTINGS}.
      */
-    @SkipPresubmit(reason = "Flaky: b/179554972; add to presubmit after fixing")
     @Test
+    @IgnoreUpTo(Build.VERSION_CODES.R)
     public void testRequestBackgroundNetwork() throws Exception {
         // Create a tun interface. Use the returned interface name as the specifier to create
         // a test network request.
-        final TestNetworkInterface testNetworkInterface = runWithShellPermissionIdentity(() -> {
-            final TestNetworkManager tnm =
-                    mContext.getSystemService(TestNetworkManager.class);
-            return tnm.createTunInterface(new LinkAddress[]{TEST_LINKADDR});
-        }, android.Manifest.permission.MANAGE_TEST_NETWORKS,
+        final TestNetworkManager tnm = runWithShellPermissionIdentity(() ->
+                mContext.getSystemService(TestNetworkManager.class),
+                android.Manifest.permission.MANAGE_TEST_NETWORKS);
+        final TestNetworkInterface testNetworkInterface = runWithShellPermissionIdentity(() ->
+                    tnm.createTunInterface(new LinkAddress[]{TEST_LINKADDR}),
+                android.Manifest.permission.MANAGE_TEST_NETWORKS,
                 android.Manifest.permission.NETWORK_SETTINGS);
         assertNotNull(testNetworkInterface);
 
@@ -1583,24 +1601,23 @@
         assertThrows(SecurityException.class,
                 () -> mCm.requestBackgroundNetwork(testRequest, null, callback));
 
+        Network testNetwork = null;
         try {
             // Request background test network via Shell identity which has NETWORK_SETTINGS
             // permission granted.
             runWithShellPermissionIdentity(
                     () -> mCm.requestBackgroundNetwork(testRequest, null, callback),
-                    android.Manifest.permission.NETWORK_SETTINGS);
+                    new String[] { android.Manifest.permission.NETWORK_SETTINGS });
 
             // Register the test network agent which has no foreground request associated to it.
             // And verify it can satisfy the background network request just fired.
             final Binder binder = new Binder();
-            runWithShellPermissionIdentity(() -> {
-                final TestNetworkManager tnm =
-                        mContext.getSystemService(TestNetworkManager.class);
-                tnm.setupTestNetwork(testNetworkInterface.getInterfaceName(), binder);
-            }, android.Manifest.permission.MANAGE_TEST_NETWORKS,
-                    android.Manifest.permission.NETWORK_SETTINGS);
+            runWithShellPermissionIdentity(() ->
+                    tnm.setupTestNetwork(testNetworkInterface.getInterfaceName(), binder),
+                    new String[] { android.Manifest.permission.MANAGE_TEST_NETWORKS,
+                            android.Manifest.permission.NETWORK_SETTINGS });
             waitForAvailable(callback);
-            final Network testNetwork = callback.getLastAvailableNetwork();
+            testNetwork = callback.getLastAvailableNetwork();
             assertNotNull(testNetwork);
 
             // The test network that has just connected is a foreground network,
@@ -1608,7 +1625,7 @@
             // background if no foreground request can be satisfied. Thus, wait for a short
             // period is needed to let foreground capability go away.
             callback.eventuallyExpect(CallbackEntry.NETWORK_CAPS_UPDATED,
-                    callback.getDefaultTimeoutMs(),
+                    NETWORK_CALLBACK_TIMEOUT_MS,
                     c -> c instanceof CallbackEntry.CapabilitiesChanged
                             && !((CallbackEntry.CapabilitiesChanged) c).getCaps()
                             .hasCapability(NET_CAPABILITY_FOREGROUND));
@@ -1616,6 +1633,16 @@
             assertFalse("expected background network, but got " + nc,
                     nc.hasCapability(NET_CAPABILITY_FOREGROUND));
         } finally {
+            final Network n = testNetwork;
+            runWithShellPermissionIdentity(() -> {
+                if (null != n) {
+                    tnm.teardownTestNetwork(n);
+                    callback.eventuallyExpect(CallbackEntry.LOST,
+                            NETWORK_CALLBACK_TIMEOUT_MS,
+                            lost -> n.equals(lost.getNetwork()));
+                }
+                testNetworkInterface.getFileDescriptor().close();
+            }, new String[] { android.Manifest.permission.MANAGE_TEST_NETWORKS });
             mCm.unregisterNetworkCallback(callback);
         }
     }
diff --git a/tests/cts/net/src/android/net/cts/Ikev2VpnTest.java b/tests/cts/net/src/android/net/cts/Ikev2VpnTest.java
index 8f2d93d..c6d8d65 100644
--- a/tests/cts/net/src/android/net/cts/Ikev2VpnTest.java
+++ b/tests/cts/net/src/android/net/cts/Ikev2VpnTest.java
@@ -55,10 +55,10 @@
 import androidx.test.InstrumentationRegistry;
 
 import com.android.internal.util.HexDump;
-import com.android.internal.org.bouncycastle.x509.X509V1CertificateGenerator;
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo;
 import com.android.testutils.DevSdkIgnoreRunner;
 
+import org.bouncycastle.x509.X509V1CertificateGenerator;
 import org.junit.After;
 import org.junit.Test;
 import org.junit.runner.RunWith;
diff --git a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
index 41537a9..1046b50 100644
--- a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
+++ b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
@@ -66,19 +66,18 @@
 import android.os.Message
 import android.util.DebugUtils.valueToString
 import androidx.test.InstrumentationRegistry
-import androidx.test.runner.AndroidJUnit4
 import com.android.connectivity.aidl.INetworkAgent
 import com.android.connectivity.aidl.INetworkAgentRegistry
+import com.android.modules.utils.build.SdkLevel
 import com.android.net.module.util.ArrayTrackRecord
-import com.android.testutils.DevSdkIgnoreRule
 import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
 import com.android.testutils.RecorderCallback.CallbackEntry.Available
 import com.android.testutils.RecorderCallback.CallbackEntry.Lost
 import com.android.testutils.TestableNetworkCallback
 import org.junit.After
 import org.junit.Assert.assertArrayEquals
 import org.junit.Before
-import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.ArgumentMatchers.any
@@ -126,11 +125,11 @@
     it.obj = obj
 }
 
-@RunWith(AndroidJUnit4::class)
+@RunWith(DevSdkIgnoreRunner::class)
+// NetworkAgent is not updatable in R-, so this test does not need to be compatible with older
+// versions. NetworkAgent was also based on AsyncChannel before S so cannot be tested the same way.
+@IgnoreUpTo(Build.VERSION_CODES.R)
 class NetworkAgentTest {
-    @Rule @JvmField
-    val ignoreRule = DevSdkIgnoreRule(ignoreClassUpTo = Build.VERSION_CODES.R)
-
     private val LOCAL_IPV4_ADDRESS = InetAddresses.parseNumericAddress("192.0.2.1")
     private val REMOTE_IPV4_ADDRESS = InetAddresses.parseNumericAddress("192.0.2.2")
 
@@ -324,7 +323,9 @@
             addCapability(NET_CAPABILITY_NOT_SUSPENDED)
             addCapability(NET_CAPABILITY_NOT_ROAMING)
             addCapability(NET_CAPABILITY_NOT_VPN)
-            addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
+            if (SdkLevel.isAtLeastS()) {
+                addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
+            }
             if (null != name) {
                 setNetworkSpecifier(StringNetworkSpecifier(name))
             }
@@ -561,8 +562,10 @@
             addTransportType(TRANSPORT_TEST)
             addTransportType(TRANSPORT_VPN)
             removeCapability(NET_CAPABILITY_NOT_VPN)
-            addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
             setTransportInfo(VpnTransportInfo(VpnManager.TYPE_VPN_SERVICE))
+            if (SdkLevel.isAtLeastS()) {
+                addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
+            }
         }
         val defaultNetwork = mCM.activeNetwork
         assertNotNull(defaultNetwork)
diff --git a/tests/cts/net/util/Android.bp b/tests/cts/net/util/Android.bp
index c36d976..88a2068 100644
--- a/tests/cts/net/util/Android.bp
+++ b/tests/cts/net/util/Android.bp
@@ -15,6 +15,10 @@
 //
 
 // Common utilities for cts net tests.
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 java_library {
     name: "cts-net-utils",
     srcs: ["java/**/*.java", "java/**/*.kt"],
@@ -23,4 +27,4 @@
         "junit",
         "net-tests-utils",
     ],
-}
\ No newline at end of file
+}
diff --git a/tests/cts/tethering/Android.bp b/tests/cts/tethering/Android.bp
index b1d4a60..824c874 100644
--- a/tests/cts/tethering/Android.bp
+++ b/tests/cts/tethering/Android.bp
@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
 android_test {
     name: "CtsTetheringTest",
     defaults: ["cts_defaults"],