said by DoYouKnowMe :

While I feel your pain, since you are a residential customer (I am presuming), you are bound by the Terms Of Service agreement that was provided to you at time of sign-up and which is easily accessible through their website. A few key passages:

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"7. USE OF SERVICES
You agree that the Services and the Comcast Equipment will be used only by you and the members of your immediate household living with you at the same address and only for personal, residential, non-commercial purposes, unless otherwise specifically authorized by us in writing. You will not use the Comcast Equipment at any time at an address other than the Premises without our prior written authorization. You agree and represent that you will not resell or permit another to resell the Services in whole or in part. You will not use or permit another to use the Comcast Equipment or the Service(s), directly or indirectly, for any unlawful purpose, including, but not limited to, in violation of any posted Comcast policy applicable to the Services. Use of the Comcast Equipment or Services for transmission, communications or storage of any information, data or material in violation of any U.S. federal, state or local regulation or law is prohibited.

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Now, they key point to the use of Sandvine, of which I have not confirmed due to lack of research ( I am lazy ), is pointed out in Section 7. A P2P connection requires you to "authorize" someone else to use the service...