If WiFi is off, then the packet sniffer (i.e. Wireshark software plus whatever 802.11 hardware is in use) will NOT be able to pick up any 802.11 traffic from the device. However, note that you usually have a SIM card for connection that supports data over cellular; if this is the traffic he is able to capture, then turning wifi off won't help. I don't know of any capture systems for 3G/4G and the like that feed into Wireshark, but they may exist.
If it is 802.11 wifi in use, hopefully encryption is enabled with WPA2 which will make it harder to read the data captured.
How do I know if I have a SIM card? I have an iPhone 7
Asked: 2018-01-29 16:03:53 +0000
Seen: 1,007 times
Last updated: Jan 29 '18
Okay I do have a SIM card... how can he use wireshark over cellular... and how can I stop it? If I'm not connected to the wifi network he shouldn't be able to capture anything... otherwise anyone could capture anything from anyone
This is why we use strong encryption... Hopefully your WiFi is protected with some variant of WPA2. If you are REALLY paranoid, you then use a VPN tunnel on top of WPA2, and run something like https or some other TLS encrypted traffic inside the tunnel.
This is a bit dated, but discusses your cellular question:
https://osqa-ask.wireshark.org/questi...https://security.stackexchange.com/qu...