#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main()
{
    int fd;
    socklen_t len;
    struct sockaddr_in r, q;
    int c;

    if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        return(1);
    }

    memset(&r, '\0', sizeof r);
    r.sin_family = AF_INET;
    r.sin_addr.s_addr = INADDR_ANY;
    r.sin_port = 2000;

    if (bind(fd, (struct sockaddr *)&r, sizeof r) < 0) {
        perror("bind");
        return(1);
    }
    if (listen(fd, 5)) {
        perror("listen");
        return(1);
    }

    while (1) {
        len = sizeof q;
        if ((fd = accept(fd, (struct sockaddr *)&q, &len)) >= 0) {
	    switch (read(fd, &c, 1)) {
	    case -1:
		perror("read");
		return(1);
	    case 1:
		write(fd, &c, sizeof c);
	    }
	}
    }
}