From owner-freebsd-current  Fri Mar 17 15: 3:23 2000
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From: Archie Cobbs <archie@whistle.com>
Message-Id: <200003172303.PAA70386@bubba.whistle.com>
Subject: ICMP socket weirdness
To: freebsd-current@freebsd.org
Date: Fri, 17 Mar 2000 15:03:18 -0800 (PST)
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Can someone explain the weird behavior I'm seeing from the
program below??

When the program is run, if you ping the IP address from the
local machine, it sees packets.  However, if you ping it from
a remote machine, it doesn't see packets.

This is on a 3.4-REL machine.. it also happens on a 4.0-current
machine built on approx Feb. 2.

-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <err.h>

int
main(int ac, char *av[])
{
	struct sockaddr_in a;
	u_char buf[8192];
	int r, s;

	memset(&a, 0, sizeof(a));
	a.sin_family = AF_INET;
	a.sin_len = sizeof(a);
	if (ac != 2 || inet_aton(av[1], &a.sin_addr) == 0)
		errx(1, "Usage: stest ipaddr");
	if ((s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) == -1)
		err(1, "socket");
	if (bind(s, (struct sockaddr *)&a, sizeof(a)) == -1)
		err(1, "bind");

	while ((r = read(s, buf, sizeof(buf))) > 0)
		printf("Rec'd %d byte packet\n", r);
	if (r != 0)
		err(1, "read");
	return (0);
}



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