update ebpf to NAT only 445 tcp

ubuntu_intermediate/inter_op_ebpf.c

@@ -198,15 +198,22 @@ int inter_op_ebpf(struct xdp_md *ctx)
         //        }
     }
 
-    __u32 original_src = ip->daddr;
-    __u32 original_dst = ip->daddr;
-    __u32 *saved_saddr = ip_pool.lookup(&ip->saddr);
-    __u32 *saved_daddr = ip_pool.lookup(&ip->daddr);
+    if (ip->protocol != 6)
+        return XDP_PASS;
 
     struct tcphdr *tcp = (void *)ip + (ip->ihl * 4);
     if ((void *)tcp + sizeof(*tcp) > data_end)
         return XDP_PASS;
 
+    if (tcp->source != htons(445) && tcp->dest != htons(445)) {
+        return XDP_PASS;
+    }
+
+    __u32 original_src = ip->daddr;
+    __u32 original_dst = ip->daddr;
+    __u32 *saved_saddr = ip_pool.lookup(&ip->saddr);
+    __u32 *saved_daddr = ip_pool.lookup(&ip->daddr);
+
     if (saved_daddr)
     {
         ip->daddr = *saved_daddr;