There is an underage guest in my house for whom I will be legally responsible for the next few months and I'm concerned about some of his interactions online from some of the public postings I've seen on various Instagram accounts and other activities I've picked up. I want to gather information and validate my suspicions before confronting him.
I want to monitor all traffic that goes to his phone and computer. It's been a long while since my ethical hacking classes. How can I sniff his https traffic? Things like Instagram (most concerned about) along with Apple iMessage and such. I know about Wireshark and such but my current switch isn't allowing me to forward all traffic to my PC (and it needs to get upgraded anyway) so I'm replacing it with ubiquity. (I chose this for single vendor networking and video surveillance).
I know he is communicating through direct messaging, but I want to sniff those and see the contents of the messages. I just want to gather a few things before I confront him.
Which technique would be better for this? Would simple packet sniffing be enough, or would I need to execute some man in the middle techniques to be skirt around the x.509 protocols?
I know that the ubiquity gear has some nice DPI, but I'm really interested in the contents. Is there something in that gear that will assist with this. Can I use the USG as a proxy server?