diff --git a/src/install.sh b/src/install.sh
new file mode 100755
index 0000000..bf11d28
--- /dev/null
+++ b/src/install.sh
@@ -0,0 +1 @@
+sudo apt-get install libssl-dev
\ No newline at end of file
diff --git a/src/misc.c b/src/misc.c
new file mode 100644
index 0000000..45de1b2
--- /dev/null
+++ b/src/misc.c
@@ -0,0 +1,27 @@
+#include "misc.h"
+
+char *hash_data(pub_data *data) {
+	// Copy data to buf to pass it as string argument
+	char cpy_data[data->length + 1];
+	memcpy(cpy_data, data->data, data->length);
+	cpy_data[data->length] = '\0';
+
+	// All three fields are concatenated into a single buf
+	char *concat_data = concat(3, data->id, data->seqno, data->data);
+
+	// The resulting buf is hashed
+	char *hash = SHA256(concat_data, data->length + 10, 0);
+
+	// Free the concatenated buf
+	free(concat_data);
+
+	return hash_trunc(hash);
+}
+
+char *hash_network(list *data_list) {
+	
+}
+
+char *hash_trunc(char *hash256bit);
+
+char *concat(int argc, ...);
\ No newline at end of file
diff --git a/src/misc.h b/src/misc.h
new file mode 100644
index 0000000..737b5d0
--- /dev/null
+++ b/src/misc.h
@@ -0,0 +1,23 @@
+#ifndef MISC_H
+#define MISC_H
+
+#include <openssl/sha.h>
+#include <stdarg.h>
+#include "node.h"
+#include "tlv.h"
+
+// General list
+typedef struct list {
+	void *data;
+	void *next;	
+} list;
+
+// Hash functions
+char *hash_data(pub_data *data);
+char *hash_network(list *data_list);
+char *hash_trunc(char *hash256bit);
+char *concat(int argc, ...);
+
+
+
+#endif
\ No newline at end of file
diff --git a/src/node.c b/src/node.c
index 79aa5e9..fe718a3 100644
--- a/src/node.c
+++ b/src/node.c
@@ -1,50 +1,248 @@
 // This is the main file of the Dazibao project. It represents the node, and
 // handles all of the main logic, including the network connexions.
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <string.h>
 
+#include "tlv.h"
+#include "node.h"
 
-// Will return a packet when we receive one that's valid.
-packet listen_for_packets(){
+// For every packet recivied,
+// then we make sure it's conform
+// We then extract the data from it to make it easy to work with
+int check_header(char * req[], int buffer_size, packet * packet_to_return){
 
+    packet * packet_to_return = (packet*) req;
+
+    // We need to check a few things ;
+    // The first byte must be worth 95,
+    if (packet_to_return->magic != 95) {
+        perror(">> The magic number of the packet is no good.");
+        return -1;
+    }
+
+    // The second byte must be worth 1,
+    if (packet_to_return->version != 1) {
+        perror(">> The version number of the packet is no good.");
+        return -1;
+    }
+
+    if (packet_to_return.length + 4 > buffer_size  ) {
+        perror(">> The packet length is bigger than the UDP datagram, which is not possible with the current laws of physics.");
+        return -1;
+    }
+
+    return 0;
 }
 
+// We listen forever for new paquets;
+void listen_for_packets(){
+
+    // Create new socket for UDP
+    int s = socket(AF_INET6, SOCK_DGRAM, 0);
+
+    if(s < 0) {
+        perror(">> Error, cannot create socket.");
+        perror(">> Exiting...")
+        exit(1);
+    }
+
+    struct sockaddr_in6 server;
+    memset(&server, 0, sizeof(server));
+
+    server.sin6_family = AF_INET6;
+    server.sin6_port = htons(LISTEN_PORT);
+    int rc = bind(s, (struct sockaddr*)&server, sizeof(server));
+    if(rc < 0) {
+        perror(">> Error, cannot bind socket to choosen port.");
+        perror(">> Exiting...")
+        exit(1);
+    }
+
+    // A paquet has at most a length of 1024 bytes
+    char req[1024];
+    struct sockaddr_in6 client;
+    struct iovec io = { .iov_len = 1024, .iov_base = req };
+    struct msghdr msg_to_receive = {
+        .msg_name = &client,
+        .msg_namelen = sizeof(client),
+        .msg_iov = &io,
+        .msg_iovlen = 1
+    };
+    while(1){
+        memset(req, '\0', 1024);
+
+        struct sockaddr_in6 client;
+        unsigned int client_len = sizeof(client);
+
+        rc = recvmsg(s, &msg_to_receive, 0);
+        if(rc < 0) {
+            perror(">> Error while receiving a new datagram.");
+            perror(">> Ignoring, continuing...")
+            continue;
+        }
+
+        printf(">> New paquet received :\n");
+        printf("%s\n", req);
+
+        // We verify the received packet is well formated,
+        // and we return it in the struct designed to work with it.
+        struct packet * formated_rec_datagram;
+        if(check_header(&req, 1024, formated_rec_datagram) < 0){
+            perror(">> Error while checking the header, aborting this packet, by choice, and conviction.");
+            continue;
+        }
+
+        struct tlv_list received_tlvs;
+        if (validate_tlvs(formated_rec_datagram) < 0) {
+
+            /* code */
+        }
+    }
+}
+
+
+
+
+// If the sender is not in the neighbourhood, and we have 15 neighbours, we
+// ignore the packet. Otherwise, we add him to the neighbourhood, marked as
+// temporary.
+int update_neighbours(){
+
+};
+
 // We need to make sure the TLV announces a length that will no go onto
 // another tlv, as we might end up reading bullshit.
-int validate_tlv(unsigned char *data, int pos){
-    switch(data[pos]) {
-        case 0:
-            break;
-        case 1:
-            break;
-        case 2:
-            if(data[pos+1] != 0) return 0;
-            break;
-        case 3:
-            if(data[pos+1] != 18) return 0;
-            break;
-        case 4:
-            if(data[pos+1] != 16) return 0;
-            break;
-        case 5:
-            if(data[pos+1] != 0) return 0;
-            break;
-        case 6:
-            if(data[pos+1] != 26) return 0;
-            break;
-        case 7:
-            if(data[pos+1] != 8) return 0;
-            break;
-        case 8:
-            if(data[pos+1] < 26 || data[pos+1] > 218) return 0;
-            break;
-        case 9:
-            break;
-        default:
-            return 0;
-    }
+int validate_tlv(char *data, int pos, short packet_len){
+    char type = data[pos];
 
-    return 1;
+    // Nothing to do in this case
+    if(type == 0)
+        return 0;
+
+    // Check that we can read a length
+    if(pos + 1 >= packet_len)
+        return -1;
+
+    unsigned char tlv_len = data[pos+1];
+
+    // Check that the tlv does not exceed the packet length
+    if(pos + length >= packet_len)
+        return -1;
+
+    // Returns the type of the tlv or -1 if something went wrong
+    switch(type) {
+        case 1:
+            return 1;
+        case 2:
+            if(tlv_len != LEN_NEIGHBOUR_REQ) return -1;
+            return 2;
+        case 3:
+            if(tlv_len != LEN_NEIGHBOUR) return -1;
+            return 3;
+        case 4:
+            if(tlv_len != LEN_NETWORK_HASH) return -1;
+            return 4;
+        case 5:
+            if(tlv_len != LEN_NETWORK_STATE_REQ) return -1;
+            return 5;
+        case 6:
+            if(tlv_len != LEN_NODE_HASH) return -1;
+            return 6;
+        case 7:
+            if(tlv_len != LEN_NODE_STATE_REQ) return -1;
+            return 7;
+        case 8:
+            if(tlv_len < MIN_LEN_NODE_STATE || tlv_len > MAX_LEN_NODE_STATE) return -1;
+            return 8;
+        case 9:
+            return 9;
+        default:
+            return -1;
+    }
 }
 
+// We then look at the differents TLVs in the packet.
+void work_with_tlvs(char *data, short packet_len){
+    int pos = 0;
+    unsigned char tlv_len;
+    tlv tmp_tlv;
+
+    while(pos < packet_len) {
+        switch(validate_tlv(data, pos, packet_len)) {
+            case 0:
+                // We received a padding tlv so it is ignored
+                pos += 1;
+                break;
+            case 1:
+                // We received a padding tlv so it is ignored
+                tlv_len = data[pos+1];
+                pos += tlv_len + 2;
+                break;
+            case 2:
+                // We received a neighbour request so a neighbor tlv has to be sent
+                tlv_len = data[pos+1];
+                pos += tlv_len + 2;
+
+                // NOT FINISHED - Where are ip and seqno stored?
+                build_neighbour(&tmp_tlv, ip, seqno);
+                // NOT FINISHED - What packet is it added to?
+                add_tlv(packet, &tmp_tlv, 3);
+                break;
+            case 3:
+                // We received a neighbour tlv so a tlv network hash is sent to that address
+                tlv_len = data[pos+1];
+                pos += tlv_len + 2;
+
+                tlv.neighbour = (neighbour*) (data + pos);
+                break;
+            case 4:
+                // We reveived a network hash tlv so  
+                tlv_len = data[pos+1];
+                pos += tlv_len +2;
+
+                // NOT FINISHED - Where is network_hash?
+                build_neighbour(&tmp_tlv, network_hash);
+                // NOT FINISHED - What packet is it added to?
+                add_tlv(packet, &tmp_tlv, 4);
+                break;
+            case 5:
+                // We received a network state request tlv so a series of tlv node hash have to be sent for each data known
+                pos += 2;
+
+                // NOT FINISHED - for each known data
+                list *tmp_list = data_list;
+                pub_data *tmp_data;
+
+                while(tmp_list != NULL) {
+                	tmp_data = (pub_data*) tmp_list->data;
+                	build_node_hash(&tmp_tlv, tmp_data->id, tmp_data->seqno);
+                }
+
+                break;
+            case 6:
+                // We received a node hash tlv
+                break;
+            case 7:
+                // We received a node state request tlv
+                break;
+            case 8:
+                // We received a node state tlv
+                break;
+            case 9:
+                // We received a warning tlv so it's message is printed
+                break;
+            default:
+                return ;
+        }
+    }
+}
+
+
+
 void work_with_tlvs(struct tlvs_list receivied_tlvs){
 
     // For every TLV,
@@ -84,10 +282,10 @@ void work_with_tlvs(struct tlvs_list receivied_tlvs){
                 // we store the entry in our data table.
 }
 
-int main(int argc, char const *argv[]) {
-    int continue = 1;
-    
-    while(continue){
+int main(int argc, const char *argv[]) {
+    int cont = 1;
+
+    while(cont){
 
         // We create the neighbourhood table
         neighbour_peer neighbour_list[NEIGHBOUR_MAX];
@@ -97,17 +295,8 @@ int main(int argc, char const *argv[]) {
 
         // Listen for incoming packets
         listen_for_packets();
-        // For every packet recivied, we fork,
-        // then we make sure it's conform
-        // We then extract the data from it to make it easy to work with
-        check_header();
-        // If the sender is not in the neighbourhood, and we have 15 neighbours, we
-        // ignore the packet. Otherwise, we add him to the neighbourhood, marked as
-        // temporary.
-        update_neighbours();
-        // We then look at the differents TLVs in the packet.
-        work_with_tlvs();
 
+        // This is in it's own fork.
         time_t delay = time(NULL) + 20;
         while(! (delay < time(NULL)){
             // Theses functions are there for general book-keeping,and run in there own
diff --git a/src/node.h b/src/node.h
index f7680ad..db3eb83 100644
--- a/src/node.h
+++ b/src/node.h
@@ -3,6 +3,12 @@
 #ifndef NODE_H
 #define NODE_H
 
+#include "tlv.h"
+#include "misc.h"
+
+// On which port do we listen to
+#define LISTEN_PORT 1212
+
 // The node ID
 #define NODE_ID 203242402519736214145149136169422092269247115186189140178187251487819615911212154252117172522111472481308026129190139512419121015210238252292031613214452118122204415160254
 
@@ -29,24 +35,31 @@ typedef struct neighbour_peer {
  * Di : the data of the message 192 bytes
 */
 
-typedef struct message {
-    long node_id_publisher;
+typedef struct pub_data {
+	unsigned char length;
+    long id;
     short seqno;
     char *data;
-} message;
+} pub_data;
+
+// static lists
+static list *data_list; 
+static list *neighbour_list;
 
 // TODO
 
 // fonctions signatures
 void listen_for_packets();
 
-void check_header();
+int check_header(char * received_datagram[], int len, packet pack);
 
-void update_neighbours();
+int update_neighbours();
+
+int validate_tlv(unsigned char *data, int pos);
 
 void work_with_tlvs();
 
-int validate_tlv(unsigned char *data, int pos);
+void add_tlv(packet *packet, tlv *tlv, char type);
 
 // threaded functions
 
diff --git a/src/tlv.h b/src/tlv.h
index bc21737..a49a8f7 100644
--- a/src/tlv.h
+++ b/src/tlv.h
@@ -6,6 +6,15 @@
 #ifndef TLV_H
 #define TLV_H
 
+#define LEN_NEIGHBOUR_REQ 0
+#define LEN_NEIGHBOUR 18
+#define LEN_NETWORK_HASH 16
+#define LEN_NETWORK_STATE_REQ 0
+#define LEN_NODE_HASH 26
+#define LEN_NODE_STATE_REQ 8
+#define MIN_LEN_NODE_STATE 26
+#define MAX_LEN_NODE_STATE 218
+
 // 8 octets min (struct pointer 4 octets), 1024 octets max
 typedef struct packet {
 	unsigned char magic; // 95 (si autre, ignorer)
@@ -99,11 +108,10 @@ typedef union tlv {
 	warning *warning;
 } tlv;
 
-
-// creer un tlv
+// build tlv from token
 int build_tlv(tlv *tlv, cmd_token token);
 
-// creer un tlv specifique
+// build specific tlv
 int build_pad1(tlv *tlv);
 int build_padn(tlv *tlv, size_t len);
 int build_neighbour_req(tlv *tlv);