illustrates a simple anti debugging technique

anti-debugging.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/ptrace.h>

void anti_debugging(void) __attribute__ ((constructor));
void run_evil_code();

void anti_debugging(void)
{
	// if we are not traced:
	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != -1)
		run_evil_code();
}

void run_evil_code()
{
	printf("evil code.\n");
}

int main(int argc, char **argv)
{
	printf("everything's fine.\n");
	return 0;
}