Re: [tor-relays] Comcast blocks ALL traffic with tor relays

FWIW I haven't ever experienced any issues using Tor on multiple Comcast residential and business lines.

I use Tor as a client daily from a Comcast residential connection and have never been unable to connect to directories or relays.

I also have a directory client running 24/7 on Comcast business and it hasn't had any Tor-related connectivity issues over the last 6+ years.

I just spun up a new /relay/ on a Comcast residential connection and have no issues talking to other relays and I've confirmed the ORPort is reachable from multiple other AS's in the US and abroad.

│ 09:11:35 [NOTICE] Self-testing indicates your ORPort is reachable from the outside. Excellent. Publishing server descriptor.
Relay Search

If anyone wants to test reachability to this Comcast relay, I'll leave it up for the next 48 hours or so.

I'm not necessarily a fan of Comcast or any of their practices and am only speaking for myself here but I haven't ever experienced any blocking or difficulty.

Are you sure that port forwarding To your relay is reliably working and that some "security feature" in your Comcast modem/router isn't causing the problem? I haven't researched any reports of Comcast blocking so I can't speak to any other anecdotal reports of said blocking. I sure hope it isn't the case. If it is, I'll certainly drop them in a flash too.




On 6/11/23 04:46, xmrk2 via tor-relays wrote:

I'd like to raise awareness of the Comcast blocking.

As stated in subject, I believe Comcast blocks all traffic between its customers and public tor relay nodes. That is, the blocking is not limited to tor-related traffic, all other services / ports on the tor relay are blocked.

Background: I am running a lightning node, lightning is a layer 2 protocol to scale Bitcoin. Lightning nodes need to be connected to each other ideally 24/7. I was contacted by the operator of another Lightning node, complaining that he cannot connect to my node. He is Comcast customer, I am not. I was also running a tor relay on the same public IPv4 address.

I am pretty sure that the blocking is done by Comcast and is triggered by being in public list of tor relays. The blocking disappeared after I stopped my tor relay and restarted my router (thus getting a new external IPv4 address). After 1 day, I relaunched the tor relay, and the blocking reappeared a few hours later. It was also confirmed by the said operator of the lightning node, who said there were various rounds of blocking tor, customers complaining and Comcast lifting the block for some time, only to reinstate the blocking later.

Comcast thus discourages me and similar people from running tor relays, or at least forces me to run tor in bridge mode. So this is an insidious attack on tor. Note that Bitcoin is not particularly relevant, Comcast is blocking tor nodes, not bitcoin nodes. So even if you hate Bitcoin, note that the same problem could arise even if Bitcoin never existed: e.g. a self-hosted web server, whose owner wants to donate his free capacity to tor by running tor relay. By doing this, he prevents any Comcast customers from accessing his web server, and this consequence is not obvious at all.

Any ideas on how to combat this? I was thinking about including some false positives in tor relay list. Imagine including some Google servers' IP addresses - Comcast customers suddenly cannot connect to Google, unless Comcast stops this blocking... or simply whitelists Google. But those false positives sound ugly and a bit malicious, not sure it is a good idea.

I already wrote about this publicly, and also wrote a mail to EFF. Hope I am not spamming, I feel this is quite important issue and am a bit frustrated by the lack of attention it gets.

tor-relays mailing list
tor-relays Info Page