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Multiple websites use "ssl.marfeelcdn.com" as CNAME #132
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This is going to get interesting as CNAME blocking becomes more and more common. I understand that PiHole is gong to start supporting CNAME based blocking as well. At the moment, I'm inclined not to take any action on this. It seems like if I start removing things just based on a CNAME, then the list will quickly become empty - as it takes no effort to setup CNAMES. But I'm going to leave this ticket open for tracking as its certainly a problem and I would appreciate other people's opinions on the issue. Thank you for opening this ticket @hectorm. |
for tracking, |
Just to add more data, I checked the CNAME records of the top million websites (with and without www) and these are the domains that use the Marfeel CDN:
This is the full list of all CNAME records. |
Thank you for the added information @hectorm |
At the moment, I am not considering CNAME blocks to be actionable because I am not blocking whatever the main domain is. CNAME blocking is beyond what hosts files block, and therefore its on the user of this this to maintain whatever whitelists are necessary to account for CNAME based blocks. |
Just ran into this too- I do a deep CNAME package inspection, and couldn't visit lifehacker.com due to this. |
Alright, |
Thanks! |
Marfeel is an advertising company of which I have no relation, but it seems that some websites use their CDN to serve content and blocking the domain
ssl.marfeelcdn.com
makes them inaccessible, since when blocking ads at DNS level many resolvers (systemd-resolved, Unbound and Knot Resolver are the ones I know with this behavior) will prevent clients from accessing a domain that has a CNAME record pointing to a blacklisted domain.I open this issue only to inform about this problem and evaluate if it would be convenient or not to remove this domain from the blacklist.
This is the list of websites that I have found with this problem:
But any website that has followed these instructions is affected by this.
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