The Lord Himself will be your firewall

"I will be an encircling wall of fire for it—oracle of the LORD—and I will be the glory in its midst.”  (Zechariah 2: 9 NABRE)

If God is for you, who can be against you?.  If God surrounds you with an impregnable firewall, who can touch you?

"Trust in the LORD with all your heart,
on your own intelligence do not rely;
In all your ways be mindful of him,
and he will make straight your paths."  (Proverbs 3: 5 - 6)