Recuperar grub

sudo mount /dev/sda3 /mnt
sudo mount /dev/sda4 /mnt/boot
sudo mount –bind /dev /mnt/dev
sudo mount –bind /dev/pts /mnt/dev/pts
sudo mount –bind /proc /mnt/proc
sudo mount –bind /sys /mnt/sys
sudo chroot /mnt
grub-install –recheck /dev/sda

NMap – Analizar la red

nmap -sP 192.168.1.1-255