Packet formats captured through wireshark for wired networks

networks-

1. Ethernet 2. IP 3.TCP 4. UDP

Program :

#include<stdio.h> //For standard things
#include<stdlib.h>
//malloc
#include<string.h>
//strlen
#include<netinet/ip_icmp.h>
//Provides declarations
#include<netinet/udp.h>
//Provides declarations for
#include<netinet/tcp.h>
//Provides declarations for
#include<netinet/ip.h>
//Provides declarations for
#include<sys/socket.h>
#include<arpa/inet.h>
for icmp header
udp header
tcp header
ip header
void ProcessPacket(unsigned char* , int);
void print_ip_header(unsigned char* , int);
void print_tcp_packet(unsigned char * , int );
void PrintData (unsigned char* , int);
int sock_raw;
FILE *logfile;
struct sockaddr_in source,dest;
int tcp=0,udp=0,icmp=0,others=0,igmp=0,total=0,i,j;
int main()
{
int saddr_size , data_size;
struct sockaddr saddr;
struct in_addr in;
unsigned char *buffer = (unsigned char *) malloc(65536);
logfile=fopen("log.txt","w");
if(logfile==NULL)
{
printf("Unable to create log.txt file.");
}
printf("Starting...\n");
printf("Starting...\n");
int sock_raw = socket( AF_INET , SOCK_RAW , IPPROTO_TCP) ;
if(sock_raw < 0)
{
//Print the error with proper message
perror("Socket Error");
return 1;
}
while(1)
{
saddr_size = sizeof saddr;
//Receive a packet
data_size = recvfrom(sock_raw , buffer , 65536 , 0 , &saddr ,
&saddr_size);
if(data_size <0 )
{
printf("Recvfrom error , failed to get packets\n");
return 1;
}
//Now process the packet
ProcessPacket(buffer , data_size);
}
close(sock_raw);printf("\nFinished");
return 0;
}
void ProcessPacket(unsigned char* buffer, int size)
{
//Get the IP Header part of this packet , excluding the ethernet header
struct iphdr *iph = (struct iphdr*)buffer;
++total;
switch (iph->protocol) //Check the Protocol and do accordingly...
{
case 1: //ICMP Protocol
++icmp;
break;
case 2: //IGMP Protocol
++igmp;
break;
case 6: //TCP Protocol
++tcp;
print_tcp_packet(buffer , size);
break;
case 17: //UDP Protocol
++udp;
break;
default: //Some Other Protocol
++others;
break;
}
printf("TCP : %d
UDP : %d
ICMP : %d
IGMP : %d
%d\r", tcp , udp , icmp , igmp , others , total);
}
Others : %d
Total :
void print_ip_header(unsigned char* Buffer, int Size)
{
unsigned short iphdrlen;
struct iphdr *iph = (struct iphdr *)Buffer;
iphdrlen =iph->ihl*4;
memset(&source, 0, sizeof(source));
source.sin_addr.s_addr = iph->saddr;
memset(&dest, 0, sizeof(dest));
dest.sin_addr.s_addr = iph->daddr;
fprintf(logfile , "\n");
fprintf(logfile , "IP Header\n");
fprintf(logfile , "
|-IP Version
: %d\n",(unsigned int)iph-
>version);
fprintf(logfile , "
|-IP Header Length : %d DWORDS or %d Bytes\n",
(unsigned int)iph->ihl,((unsigned int)(iph->ihl))*4);
fprintf(logfile , "
|-Type Of Service
: %d\n",(unsigned int)iph->tos);
fprintf(logfile , "
|-IP Total Length
: %d Bytes(Size of
Packet)\n",ntohs(iph->tot_len));fprintf(logfile , "
|-Identification
: %d\n",ntohs(iph->id));
fprintf(logfile , "
|-TTL
: %d\n",(unsigned int)iph->ttl);
fprintf(logfile , "
|-Protocol : %d\n",(unsigned int)iph->protocol);
fprintf(logfile , "
|-Checksum : %d\n",ntohs(iph->check));
fprintf(logfile , "
|-Source IP
:
%s\n",inet_ntoa(source.sin_addr));
fprintf(logfile , "
|-Destination IP
: %s\n",inet_ntoa(dest.sin_addr));
}
void print_tcp_packet(unsigned char* Buffer, int Size)
{
unsigned short iphdrlen;
struct iphdr *iph = (struct iphdr *)Buffer;
iphdrlen = iph->ihl*4;
struct tcphdr *tcph=(struct tcphdr*)(Buffer+iphdrlen);
fprintf(logfile , "\n\n***********************TCP
Packet*************************\n");
print_ip_header(Buffer,Size);
fprintf(logfile , "\n");
fprintf(logfile , "IP Header\n");
PrintData(Buffer,iphdrlen);
fprintf(logfile , "TCP Header\n");
PrintData(Buffer+iphdrlen,tcph->doff*4);
fprintf(logfile , "Data Payload\n");
PrintData(Buffer + iphdrlen + tcph->doff*4 , (Size - tcph->doff*4-iph-
>ihl*4));
}
//Move the pointer ahead and reduce the size of string*/
void PrintData (unsigned char* data , int Size)
{
int i , j;
for(i=0 ; i < Size ; i++)
{
if( i!=0 && i%16==0)
//if one line of hex printing is complete
{
fprintf(logfile , "
");
for(j=i-16 ; j<i ; j++)
{
if(data[j]>=32 && data[j]<=128)
fprintf(logfile , "%c",(unsigned char)data[j]); //if its a
number or alphabet
else fprintf(logfile , "."); //otherwise print a dot
}
fprintf(logfile , "\n");
}
if(i%16==0) fprintf(logfile , "
");
fprintf(logfile , " %02X",(unsigned int)data[i]);
if( i==Size-1) //print the last spaces
{
for(j =0;j<15-i%16;j++)
{
fprintf(logfile , "
"); //extra spaces
}
fprintf(logfile , "
");
for(j=i-i%16 ; j<=i ;
{
if(data[j]>=32 &&
{
fprintf(logfile
}
else
{
fprintf(logfile
}
}
}
}
fprintf(logfile ,
j++)
data[j]<=128)
, "%c",(unsigned char)data[j]);
, ".");
"\n" );
}
/*Output:
root@pl15:/home/pl15/Desktop# gcc Group-A-9.
Starting...
TCP : 241
UDP : 0
ICMP : 0
IGMP : 0
Others : 0
Total : 240*/