Cablewifi / xfinitywifi technical notes

Xfinitywifi is currently one of the most widespread open Wifi SSIDs one sees in the USA. It’s not just limited to Xfinity cable internet subscribers; other cable companies partner their subscribers in and you can pay for access as well.

Risks of using Xfinitywifi

The usual risks of using open Wifi or any non-certificated non-802.1x Wifi exist with xfinitywifi. You are subject to eavesdropping, man in the middle attacks, et al. One can use typical services like SSH, VPN, etc over xfinitywifi to help mitigate security risks.

Xfinity pushes their app giving you access to a currently very limited deployment of “XFINITY” WPA SSIDs. As of this writing, I rarely see the XFINITY APs, and I’ll bet Comcast loves getting the extra info allowed by the app permissions. You don’t need or want the app most likely.

Like most open AP schemes including Gogo and hotel wifi, xfinitywifi uses the MAC address of your device as a sort of “cookie” so that you sign in once. You connect to the xfinitywifi AP, and a webpage signin results. xfinitywifi remembers you via the MAC ID nationwide for at least months. If you have a Wifi-capable wearable, you’ll need a web browser on the wearable to sign in, or use a more capable device to sign in once with the MAC.

Maximum range of xfinitywifi

The usual range limits of 2.4 GHz and 5 GHz Wifi apply. You are simply on a VLAN-like network (separated from host subscriber network). The range really depends on how the subscriber has their Xfinity router placed.

Staying in a duplex/condo? Might pickup the router in the adjoining unit in some parts of your unit.

Router in the basement? Might not pick it up across the street.

Router next to the living room window facing the street? Might pick it up across the street and a house or two down (assuming closely spaced houses e.g. urban).

Note that the xfinitywifi maps seem to omit many APs, I suppose it’s better that they are conservative. I wouldn’t plan on using a specific AP when traveling as the person could have moved, have their router in a poor location, or opted out of serving xfinitywifi. For security, one might consider tethering with their 4G device instead as in general when traveling.

Speed of xfinitywifi

Assuming a good signal > -70 dBm without interference, you might get > 10 Mbps download and > 1 Mbps upload. Good enough for basic HD video streaming and video chat.