I have been running a couple home web cams that I can view when away from home, by opening ports on my router. They are strongly password protected.
An IPCam forum that I read says that you should never ever open ports, but should instead use a VPN. The forum explains that hackers can penetrate these ports and install/run malicious code. But they don't detail HOW hackers do this or whether passwords solve the problem or not.
My new (installing soon) router has a VPN built in so it shouldn't be a problem to set that up. I just want to know the "why".