[jebblue]

He's connecting to his neighbor's router seemingly without permission.

"When you rent a cable modem/router combo from Comcast (as one of my nearby neighbors apparently does)"

It may be illegal:

http://en.wikipedia.org/wiki/Legality_of_piggybacking

Comcast is not on the EFF's list of Wireless Friendly ISP's (referenced in the Wiki article):

https://www.eff.org/pages/wireless-friendly-isps

Even if it were: http://compnetworking.about.com/od/wirelessfaqs/f/legal_free...

"Using a neighbor's wireless access point may not be legal even with their permission. "

[icehawk]

xfinitywifi is provided by Comcast, you need a valid comcast login to connect. He is a Comcast subscriber himself, and thus he has a valid Comcast login.

[jebblue]

It has not been proven that Comcast has the authority to do this:

https://www.techdirt.com/articles/20141208/13222529362/comca...

It has been proven that in many places at least in the US, it is illegal and in some cases is a felony.

Edit: Further, it is not a good idea to connect to any known SSID unless you know for a fact that it can be trusted:

http://arstechnica.com/security/2014/06/free-wi-fi-from-xfin...

Your neighbor might be hacking you while you think you are legally using their hardware.

[tedunangst]

What is a felony? Using Comcast?

[jebblue]

Using Comcast with your own equipment and none owned by any one else outside your home? I'm not a lawyer.

Anything else including what the author describes, using his neighbor's equipment without their permission even if he thinks Comcast has the legal authority to authorize it (and documentation in the links I provided challenges that notion) then it's not for me to say; I'm not a lawyer.