diff --git a/xdp/xdp_udp.c b/xdp/xdp_udp.c
index de1b221..9d28cdd 100644
--- a/xdp/xdp_udp.c
+++ b/xdp/xdp_udp.c
@@ -31,35 +31,23 @@ int xdp_udp_func(struct xdp_md *ctx)
 	void *data_end = (void *)(long)ctx->data_end;
 	void *data = (void *)(long)ctx->data;
 
-	unsigned short mask = 0x4000;//0b 0100 0000 0000 0000
-	int DF_offset = 21;
-
 	struct ethhdr *eth = data; //structure ethernet from if_ether.h
-	int rc = XDP_PASS; // return code
-	int ipsize;
-	__u16 header_proto; __u64 length_header_eth;
 
-	length_header_eth = sizeof(*eth);//length in bits of header eth
+	// Check that our packet ethernet headers is big enough, ie. at least the size of Ethernet's fixed headers
+	if((void*)(eth + 1) > data_end) {
+		return XDP_PASS;
+	}
 
-	if(data + length_header_eth > data_end)//monitor the bound data
-		return rc;
-	header_proto = eth->h_proto;
-
-	//Enter only if it's IPV4
-	if(header_proto == bpf_htons(ETH_P_IP))
-	{
-		//We monitor protocol IPV4, we want only UDP packet
-		struct iphdr *ip = data + length_header_eth;
-		ipsize = sizeof(struct iphdr);
-		if(ip + ipsize > data_end) {
-			return rc;
+	// Check that the ethernet header declares an IPv4 packet
+	if(eth->h_proto == bpf_htons(ETH_P_IP)) {
+		struct iphdr *ip = (struct iphdr*)(eth + 1);
+		// Check that the IP packet is big enough, ie. at least the size of IP's fixed headers
+		if((void*)(ip + 1) > data_end) {
+			return XDP_PASS;
 		}
+
 		if(ip->protocol == IPPROTO_UDP) {
-			//On souhaite modifier le 21eme byte
-			// Unsigned short fait 2 bytes
-			unsigned short *p = data + DF_offset +1 ;
-			if(p > data_end) return rc;
-			p[0] = p[0] || mask;
+			ip->frag_off |= 0x4000; //Set the DF flag to 1 -> 0b 0100 0000 0000 0000
 		}
 	}