diff --git a/CHANGELOG.md b/CHANGELOG.md
index 12f9b54..90efd6e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,11 @@
 All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ---
+---
+###
+# [0.8.17] - 2024-09-06
+- Refactor of L4 csum ipv4 
+  
 ###
 # [0.8.16] - 2024-09-02
 - Fixed incorrect waitpid success/failure conditional checks in zfw.c and zfw_tunnel_wrapper.c.  This did not cause an operational issue but would not
diff --git a/src/zfw.c b/src/zfw.c
index 32deec3..55a3ace 100644
--- a/src/zfw.c
+++ b/src/zfw.c
@@ -246,7 +246,7 @@ char *direction_string;
 char *masq_interface;
 char check_alt[IF_NAMESIZE];
 
-const char *argp_program_version = "0.8.16";
+const char *argp_program_version = "0.8.17";
 struct ring_buffer *ring_buffer;
 
 __u32 if_list[MAX_IF_LIST_ENTRIES];
diff --git a/src/zfw_monitor.c b/src/zfw_monitor.c
index 3f3b629..7615672 100644
--- a/src/zfw_monitor.c
+++ b/src/zfw_monitor.c
@@ -85,7 +85,7 @@ char check_alt[IF_NAMESIZE];
 char doc[] = "zfw_monitor -- ebpf firewall monitor tool";
 const char *rb_map_path = "/sys/fs/bpf/tc/globals/rb_map";
 const char *tproxy_map_path = "/sys/fs/bpf/tc/globals/zt_tproxy_map";
-const char *argp_program_version = "0.8.16";
+const char *argp_program_version = "0.8.17";
 union bpf_attr rb_map;
 int rb_fd = -1;
 
diff --git a/src/zfw_tc_ingress.c b/src/zfw_tc_ingress.c
index 87a5307..cae74e0 100644
--- a/src/zfw_tc_ingress.c
+++ b/src/zfw_tc_ingress.c
@@ -1897,25 +1897,19 @@ int bpf_sk_splice(struct __sk_buff *skb){
                         }
                         /*Calculate l4 Checksum*/
                         int flags = BPF_F_PSEUDO_HDR;
-                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), 0, l3_sum, flags);
-                        iph = (struct iphdr *)(skb->data + sizeof(*eth));
-                        if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
-                            return TC_ACT_SHOT;
-                        }
-                        tuple = (struct bpf_sock_tuple *)(void*)(long)&iph->saddr;
-                        if(!tuple){
-                            return TC_ACT_SHOT;
-                        }
-                        tuple_len = sizeof(tuple->ipv4);
-                        if ((unsigned long)tuple + tuple_len > (unsigned long)skb->data_end){
-                            return TC_ACT_SHOT;
-                        }
-                        tcph = (struct tcphdr *)((unsigned long)iph + sizeof(*iph));
-                        if ((unsigned long)(tcph + 1) > (unsigned long)skb->data_end){
-                            return TC_ACT_SHOT;
-                        }
+                        struct l4_change_fields{
+                            __u32 daddr;
+                            __u16 dport;
+                        };
+                        struct l4_change_fields old_fields = {0};
+                        struct l4_change_fields new_fields = {0};
+                        old_fields.daddr = local_ip4->ipaddr[0];
+                        old_fields.dport = mk.sport;
+                        new_fields.daddr = mv->__in46_u_origin.ip;
+                        new_fields.dport = mv->o_sport;
+                        __u32 l4_sum = bpf_csum_diff((__u32 *)&old_fields, sizeof(old_fields), (__u32 *)&new_fields, sizeof(new_fields), 0);
                         tcph->dest = mv->o_sport;
-                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), mk.sport , mv->o_sport, flags | 2);
+                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), 0, l4_sum, flags);
                         iph = (struct iphdr *)(skb->data + sizeof(*eth));
                         if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
                             return TC_ACT_SHOT;
@@ -1931,7 +1925,7 @@ int bpf_sk_splice(struct __sk_buff *skb){
                         tcph = (struct tcphdr *)((unsigned long)iph + sizeof(*iph));
                         if ((unsigned long)(tcph + 1) > (unsigned long)skb->data_end){
                             return TC_ACT_SHOT;
-                        }  
+                        }
                     }
                 }
                 tcp_state_key.__in46_u_dst.ip = tuple->ipv4.saddr;
@@ -2121,7 +2115,19 @@ int bpf_sk_splice(struct __sk_buff *skb){
                         /*Calculate l4 Checksum*/
                         if(udph->check != 0){
                             int flags = BPF_F_PSEUDO_HDR;
-                            bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), 0, l3_sum, flags);
+                            struct l4_change_fields{
+                                __u32 daddr;
+                                __u16 dport;
+                            };
+                            struct l4_change_fields old_fields = {0};
+                            struct l4_change_fields new_fields = {0};
+                            old_fields.daddr = local_ip4->ipaddr[0];
+                            old_fields.dport = mk.sport;
+                            new_fields.daddr = mv->__in46_u_origin.ip;
+                            new_fields.dport = mv->o_sport;
+                            __u32 l4_sum = bpf_csum_diff((__u32 *)&old_fields, sizeof(old_fields), (__u32 *)&new_fields, sizeof(new_fields), 0);
+                            udph->dest = mv->o_sport;
+                            bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), 0, l4_sum, flags);
                             iph = (struct iphdr *)(skb->data + sizeof(*eth));
                             if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
                                 return TC_ACT_SHOT;
@@ -2138,20 +2144,6 @@ int bpf_sk_splice(struct __sk_buff *skb){
                             if ((unsigned long)(udph + 1) > (unsigned long)skb->data_end){
                                 return TC_ACT_SHOT;
                             }
-                            udph->dest = mv->o_sport;
-                            bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), mk.sport , mv->o_sport, flags | 2);
-                            iph = (struct iphdr *)(skb->data + sizeof(*eth));
-                            if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
-                                return TC_ACT_SHOT;
-                            }
-                            tuple = (struct bpf_sock_tuple *)(void*)(long)&iph->saddr;
-                            if(!tuple){
-                                return TC_ACT_SHOT;
-                            }
-                            tuple_len = sizeof(tuple->ipv4);
-                            if ((unsigned long)tuple + tuple_len > (unsigned long)skb->data_end){
-                                return TC_ACT_SHOT;
-                            }
                         }else{
                             udph->dest = mv->o_sport;
                         }
diff --git a/src/zfw_tc_outbound_track.c b/src/zfw_tc_outbound_track.c
index 8c58084..0fc48c3 100644
--- a/src/zfw_tc_outbound_track.c
+++ b/src/zfw_tc_outbound_track.c
@@ -2374,25 +2374,19 @@ int bpf_sk_splice6(struct __sk_buff *skb){
                 }
                 /*Calculate l4 Checksum*/
                 int flags = BPF_F_PSEUDO_HDR;
-                bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), 0, l3_sum, flags);
-                iph = (struct iphdr *)(skb->data + sizeof(*eth));
-                if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
-                    return TC_ACT_SHOT;
-                }
-                tuple = (struct bpf_sock_tuple *)(void*)(long)&iph->saddr;
-                if(!tuple){
-                    return TC_ACT_SHOT;
-                }
-                tuple_len = sizeof(tuple->ipv4);
-                if ((unsigned long)tuple + tuple_len > (unsigned long)skb->data_end){
-                    return TC_ACT_SHOT;
-                }
-                tcph = (struct tcphdr *)((unsigned long)iph + sizeof(*iph));
-                if ((unsigned long)(tcph + 1) > (unsigned long)skb->data_end){
-                    return TC_ACT_SHOT;
-                }
+                struct l4_change_fields{
+                    __u32 saddr;
+                    __u16 sport;
+                };
+                struct l4_change_fields old_fields = {0};
+                struct l4_change_fields new_fields = {0};
+                old_fields.saddr = mv.__in46_u_origin.ip;
+                old_fields.sport = tcph->source;
+                new_fields.saddr = local_ip4->ipaddr[0];
+                new_fields.sport = rand_source_port;
+                __u32 l4_sum = bpf_csum_diff((__u32 *)&old_fields, sizeof(old_fields), (__u32 *)&new_fields, sizeof(new_fields), 0);
                 tcph->source = rand_source_port;
-                bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), mv.o_sport , rand_source_port, flags | 2);
+                bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct tcphdr, check), 0, l4_sum, flags);
                 iph = (struct iphdr *)(skb->data + sizeof(*eth));
                 if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
                     return TC_ACT_SHOT;
@@ -2408,7 +2402,7 @@ int bpf_sk_splice6(struct __sk_buff *skb){
                 tcph = (struct tcphdr *)((unsigned long)iph + sizeof(*iph));
                 if ((unsigned long)(tcph + 1) > (unsigned long)skb->data_end){
                     return TC_ACT_SHOT;
-                }               
+                }
             }
             unsigned long long tstamp = bpf_ktime_get_ns();
             struct tcp_state *tstate;
@@ -2630,7 +2624,20 @@ int bpf_sk_splice6(struct __sk_buff *skb){
                     /*Calculate l4 Checksum if checksum not equal to zero*/
                     if(udph->check != 0){
                         int flags = BPF_F_PSEUDO_HDR;
-                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), 0, l3_sum, flags);
+                        struct l4_change_fields{
+                            __u32 saddr;
+                            __u16 sport;
+                        };
+                        struct l4_change_fields old_fields = {0};
+                        struct l4_change_fields new_fields = {0};
+                        old_fields.saddr = mv.__in46_u_origin.ip;
+                        old_fields.sport = udph->source;
+                        new_fields.saddr = local_ip4->ipaddr[0];
+                        new_fields.sport = rand_source_port;
+                        udph->source = rand_source_port;
+                        __u32 l4_sum = bpf_csum_diff((__u32 *)&old_fields, sizeof(old_fields), (__u32 *)&new_fields, sizeof(new_fields), 0);
+                        udph->source = rand_source_port;
+                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), 0, l4_sum, flags);
                         iph = (struct iphdr *)(skb->data + sizeof(*eth));
                         if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
                             return TC_ACT_SHOT;
@@ -2647,20 +2654,6 @@ int bpf_sk_splice6(struct __sk_buff *skb){
                         if ((unsigned long)(udph + 1) > (unsigned long)skb->data_end){
                             return TC_ACT_SHOT;
                         }
-                        udph->source = rand_source_port;
-                        bpf_l4_csum_replace(skb, sizeof(struct ethhdr) + sizeof(struct iphdr) + offsetof(struct udphdr, check), mv.o_sport , rand_source_port, flags | 2);
-                        iph = (struct iphdr *)(skb->data + sizeof(*eth));
-                        if ((unsigned long)(iph + 1) > (unsigned long)skb->data_end){
-                            return TC_ACT_SHOT;
-                        }
-                        tuple = (struct bpf_sock_tuple *)(void*)(long)&iph->saddr;
-                        if(!tuple){
-                            return TC_ACT_SHOT;
-                        }
-                        tuple_len = sizeof(tuple->ipv4);
-                        if ((unsigned long)tuple + tuple_len > (unsigned long)skb->data_end){
-                            return TC_ACT_SHOT;
-                        } 
                     }else{
                         udph->source = rand_source_port;
                     }