README.md

Description

This code shows the source ip and port the flags of the packet and the sequence number

More Info

Submitted On
By	ffbbee
Level	Beginner
User Rating	3.7 (11 globes from 3 users)
Compatibility	C
Category	Internet/ Browsers/ HTML
World	C / C++
Archive File

Source Code

#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
int main(int argc, char *argv[])
{
    int s, bytes,a=0,sy=0,f=0,r=0,u=0,p=0;
	int     ac=0,syc=0,fc=0,rc=0;
    struct tcphdr *tcp;
    struct iphdr  *ip;
    struct in_addr addr;
    char      buffer[4000];
    s = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
    if (s == -1)
    {
        perror("socket() failed");
        return 1;
    }
    ip = (struct iphdr*) buffer;
    tcp = (struct tcphdr*) (buffer + sizeof(struct iphdr));
    while( (bytes = recv(s, buffer, sizeof(buffer), 0)) > 0)
    {
        addr.s_addr = ip->saddr;
		a=ntohs(tcp->ack);
		sy=ntohs(tcp->syn);
		r=ntohs(tcp->rst);
		f=ntohs(tcp->fin);
		p=ntohs(tcp->psh);
		u=ntohs(tcp->urg);
	if (ip->saddr!=inet_addr("192.168.0.113"))
	{
	printf("Packet from source:%s\nwith flags ->",inet_ntoa(addr));
	if(a==256)
	{
	printf("Ack ");
	}
	if ( sy==256)
	{printf("Syn ");
	;}
	if (f==256)
	{
	printf("Fin ");
	}
	if (r==256)
	{
	printf("Rst ");
	}
	if (p==256)
	{
	printf("Psh ");
	}
	if (u==256)
	{
	printf("Urg");
	}
	printf("\n");
	printf("With the sequence number of ->%i\n",ntohl(tcp->seq));
	printf("From port->%i\n\n",ntohs(tcp->source));
	}
    }
    if (bytes == -1)
    {
        perror("recv() failed");
        return 2;
    }
    return 0;
}