Syslinux is a System Utilities software developed by H. Peter Anvin. After our trial and test, the software is proved to be official, secure and free. Here is the official description for Syslinux:
BS Editor: SYSLINUX is a boot loader for the Linux operating system which operates off an MS-DOS/Windows FAT FileSystem. It is intended to simplify first-time installation of Linux, and for creation of rescue- and other special-purpose boot disks.
SYSLINUX can be used, when properly set up, to completely eliminate the need for distribution of raw diskette images for boot floppies. A SYSLINUX floppy can be manipulated using standard MS-DOS (or any other OS that can access an MS-DOS filesystem) tools once it has been created.
It can also be used as a PXE bootloader during network boots.