What are the avenues for attack in Sanctuary Hill?

I've only just started the settlement here and I'm wondering what the possible attack angles are. I would wager that the bridge is one potential attack direction but are there more? There's another significant gap between some bushes that seems like it warrants defending but I want to make sure before expending resources to do so. I'm especially worried that attackers will ignore the pseudo-moat and attack from any direction...

I believe there are 3, the Bridge for Raiders, the Vault path area for Supermutants, and Water for mirelurks. I've only got around 15 hours in the game so there may be more. It's worth noting that on my first character I was never attacked there, it only happened after I bumped the difficulty up.

Too add to what was said there seems to be another route. Coming out of your original house to the left side of sanctuary. Was literally just attacked moments ago by ferals coming from that direction

You can be attacked from anywhere TECHNICALLY. However, if you put up your defences correctly you will only be attacked in the previously mentioned area. Put up a ring of guard outposts and turrets. If you do this you will only be attacked in the conventional routes. Then make a focus of turrets and traps in the previously mentioned routes. Also, put bells next to the stands. Place spotlights on these previous mentioned places as well. MAKE SURE TO HOOK UP YOUR TRAPS TO A SWITCH! Every time they are used they have to be repaired. If you just hook them up to power they go off immediately.

I built a wall around the entire settlement except the bridge and nothing attacks me