They're called "cable glands" by many and "strain relief connectors" by others.
It depends of which model of box you have, so determine if it's a Dahua box or an Amcrest equivalent (Dahua cams are re-branded Dahuas).
That looks like a pretty thick cable exiting now; if that's the camera pigtail, then it should stay inside the box with the Ethernet cable plugged into it and then the connection weather-proofed as
here. Of course, install the correct connector first, do the weather-proofing last.
This may give you some insight==>>
Cable gland or alternative for PFA130-E
Or better yet, go directly to blazin912 's post
here.
If you're having a hard time locating the correct one and/or it's going to be quite a while before you resolve it, consider plugging that hole with some
duct seal to keep the bugs and bees out until you obtain the right connector; the duct seal is like dough and it removes easily when you locate the correct connector. It's only $3 for a 1 lb. brick.
Welcome to IPCT! 