diff --git a/chapter12/net-context/tc-exist-process/main.bpf.c b/chapter12/net-context/tc-exist-process/main.bpf.c
index a67b54d..f8e9383 100644
--- a/chapter12/net-context/tc-exist-process/main.bpf.c
+++ b/chapter12/net-context/tc-exist-process/main.bpf.c
@@ -7,7 +7,7 @@
 #define ETH_P_IP 0x0800 /* Internet Protocol packet	*/ // ipv4
 #define ETH_HLEN 14 /* Total octets in header.	 */
 #define TASK_COMM_LEN 16
-#define TC_ACT_OK 0
+#define TC_ACT_UNSPEC (-1)
 
 
 struct sock_key {
@@ -114,13 +114,13 @@ int on_egress(struct __sk_buff *skb) {
     void *data = (void *)(long)skb->data;
 
     if ((data + ETH_HLEN + sizeof(struct iphdr)) > data_end)
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     struct iphdr *ip_hdr = data + ETH_HLEN;
     if (ip_hdr->protocol != IPPROTO_TCP)
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     struct tcphdr *tcp_hdr = (void *)ip_hdr + sizeof(struct iphdr);
     if ((void *)tcp_hdr + sizeof(struct tcphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     key.saddr = ip_hdr->saddr;
@@ -128,7 +128,7 @@ int on_egress(struct __sk_buff *skb) {
 
     value = bpf_map_lookup_elem(&socks, &key);
     if (!value) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     u32 daddr = ip_hdr->daddr;
     u16 dport = bpf_ntohs(tcp_hdr->dest);
@@ -137,7 +137,7 @@ int on_egress(struct __sk_buff *skb) {
     bpf_printk("%s %pI4:%d", value->comm, &key.saddr, key.sport);
     bpf_printk("%s               -> %pI4:%d", value->comm, &daddr, dport);
 
-    return TC_ACT_OK;
+    return TC_ACT_UNSPEC;
 }
 
 
diff --git a/chapter12/net-context/tc/main.bpf.c b/chapter12/net-context/tc/main.bpf.c
index 07d9886..40586dd 100644
--- a/chapter12/net-context/tc/main.bpf.c
+++ b/chapter12/net-context/tc/main.bpf.c
@@ -7,7 +7,7 @@
 #define ETH_P_IP 0x0800 /* Internet Protocol packet	*/ // ipv4
 #define ETH_HLEN 14 /* Total octets in header.	 */
 #define TASK_COMM_LEN 16
-#define TC_ACT_OK 0
+#define TC_ACT_UNSPEC (-1)
 
 
 struct sock_key {
@@ -163,13 +163,13 @@ int on_egress(struct __sk_buff *skb) {
     void *data = (void *)(long)skb->data;
 
     if ((data + ETH_HLEN + sizeof(struct iphdr)) > data_end)
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     struct iphdr *ip_hdr = data + ETH_HLEN;
     if (ip_hdr->protocol != IPPROTO_TCP)
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     struct tcphdr *tcp_hdr = (void *)ip_hdr + sizeof(struct iphdr);
     if ((void *)tcp_hdr + sizeof(struct tcphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     key.saddr = ip_hdr->saddr;
@@ -179,7 +179,7 @@ int on_egress(struct __sk_buff *skb) {
 
     value = bpf_map_lookup_elem(&socks, &key);
     if (!value) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     u32 daddr = ip_hdr->daddr;
     u16 dport = bpf_ntohs(tcp_hdr->dest);
@@ -188,7 +188,7 @@ int on_egress(struct __sk_buff *skb) {
     bpf_printk("%s %pI4:%d", value->comm, &key.saddr, key.sport);
     bpf_printk("%s               -> %pI4:%d", value->comm, &daddr, dport);
 
-    return TC_ACT_OK;
+    return TC_ACT_UNSPEC;
 }
 
 
diff --git a/chapter14/hijack-tcp-to-send-data/main.bpf.c b/chapter14/hijack-tcp-to-send-data/main.bpf.c
index d6d38ab..0c1f0a4 100644
--- a/chapter14/hijack-tcp-to-send-data/main.bpf.c
+++ b/chapter14/hijack-tcp-to-send-data/main.bpf.c
@@ -29,27 +29,27 @@ int on_egress(struct __sk_buff *skb) {
     // 从 IP 首部中过滤协议类型，只处理 TCP 协议
     struct iphdr *ip_hdr = data + ETH_HLEN;
     if ((void *)ip_hdr + sizeof(struct iphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     if (ip_hdr->protocol != IPPROTO_TCP) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // TCP 协议数据过滤
     struct tcphdr *tcp_hdr = (void *)ip_hdr + sizeof(struct iphdr);
     if ((void *)tcp_hdr + sizeof(struct tcphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     if (tcp_hdr->dest != bpf_htons(8000)) {
         bpf_printk("skip port: %d", bpf_ntohs(tcp_hdr->dest));
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // 防止重复劫持，出现一直重传
     int zero = 0;
     if (bpf_map_lookup_elem(&modify_map, &tcp_hdr->source)) {
         bpf_printk("exist");
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     bpf_map_update_elem(&modify_map, &tcp_hdr->source, &zero, BPF_ANY);
     bpf_printk("hijack start");
@@ -72,13 +72,13 @@ int on_egress(struct __sk_buff *skb) {
     int ret = bpf_skb_store_bytes(skb, dest_addr_offset, &new_dest_addr, sizeof(u32), 0);
     if (ret < 0) {
         bpf_printk("replace dest addr failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     // 重新计算 IP 首部 checksum
     ret = bpf_l3_csum_replace(skb, ip_checksum_offset, old_dest_addr, new_dest_addr, sizeof(u32));
     if (ret < 0) {
         bpf_printk("bpf_l3_csum_replace failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // 替换 TCP 首部，修改目的端口
@@ -89,25 +89,25 @@ int on_egress(struct __sk_buff *skb) {
     ret = bpf_skb_store_bytes(skb, dest_port_offset, &new_dest_port, sizeof(u16), 0);
     if (ret < 0) {
         bpf_printk("replace dest port failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     // 重新计算 TCP 首部 checksum
     ret = bpf_l4_csum_replace(skb, tcp_checksum_offset, old_dest_port, new_dest_port, sizeof(u16));
     if (ret < 0) {
         bpf_printk("bpf_l4_csum_replace failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // 调整 skb 关联的数据包长度信息
     ret = bpf_skb_change_tail(skb, skb->len+increment_len, 0);
     if (ret < 0) {
         bpf_printk("bpf_skb_change_tail failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     ret = bpf_skb_pull_data(skb, 0);
     if (ret < 0) {
         bpf_printk("bpf_skb_pull_data failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // 调用 bpf_skb_change_tail 后，需要重新执行检查，否则验证器会验证失败
@@ -115,14 +115,14 @@ int on_egress(struct __sk_buff *skb) {
     data_end = (void *)(long)skb->data_end;
     ip_hdr = data + ETH_HLEN;
     if ((void *)ip_hdr + sizeof(struct iphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     if (ip_hdr->protocol != IPPROTO_TCP) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
     tcp_hdr = (void *)ip_hdr + sizeof(struct iphdr);
     if ((void *)tcp_hdr + sizeof(struct tcphdr) > data_end) {
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     // 替换 TCP payload
@@ -130,12 +130,12 @@ int on_egress(struct __sk_buff *skb) {
     ret = bpf_skb_store_bytes(skb, offset, new_payload, sizeof(new_payload), 0);
     if (ret < 0) {
         bpf_printk("overwrite payload failed: %d", ret);
-        return TC_ACT_OK;
+        return TC_ACT_UNSPEC;
     }
 
     bpf_printk("hijack end");
 
-    return TC_ACT_OK;
+    return TC_ACT_UNSPEC;
 }
 
 
diff --git a/chapter14/hijack-tcp-to-send-data/main.h b/chapter14/hijack-tcp-to-send-data/main.h
index 6e05bfb..668f778 100644
--- a/chapter14/hijack-tcp-to-send-data/main.h
+++ b/chapter14/hijack-tcp-to-send-data/main.h
@@ -1,11 +1,7 @@
 #define ETH_P_IP    0x0800      /* Internet Protocol packet */
 #define ETH_HLEN    14         /* Total octets in header.   */
 
-#define TC_ACT_UNSPEC         (-1)
-#define TC_ACT_OK               0
-#define TC_ACT_SHOT             2
-#define TC_ACT_STOLEN           4
-#define TC_ACT_REDIRECT         7
+#define TC_ACT_UNSPEC (-1)
 
 
 struct event_t {
@@ -42,4 +38,4 @@ static __always_inline int str_len(const char *s, int max_len)
     if (s[max_len - 1] != '\0')
         return max_len;
     return 0;
-}
\ No newline at end of file
+}