You could probably mount your cameras without a mounting bracket, but why would you? Use these mounting boxes and you'll have a watertight zone for your connections, the option of a stronger, more professional mount, and better protection from natural disasters and vandals. At around $10 each, they're a bargain for what you're getting.
Wasserstein Solar Panel 13 1Ft Compatible Camera & Photo and Video Surveillance
11 Review
Blink Outdoor Camera Wall Mount Bracket Set - 5-Pack Plastic Protective Housing and 360Β° Adjustable Mount with Blink Sync Module 2 Outlet Mount - for Enhanced Blink Outdoor Indoor Camera System (Black)
11 Review
Versatile Adjustable Wall Mount with Enhanced Security for Both Indoor and Outdoor Use
11 Review
TP-LINK Tapo C310 security camera white
30 Review