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Ask HN: How to stop people using my RSS reader web app as a proxy for evil sites

I'm building an RSS reader web app. It takes a list of urls for feeds, and returns links to items in the feed. Due to CORS, the requests have to go through a server. The server also parses the rss feed and just returns a few bits of relevant information. The url, title, and date of the entries. If I allow anyone to use my server to fetch any RSS feed they want. What can I do to stop someone nefarious using my server as a proxy to build a list of links to evil/illegal things? Other than building a database of trustworthy sites, which i'm not willing to do, I can't think of a solution.

phillipseamore 6y ago
Usually the RSS feed is on the same domain, so you could simply whitelist automatically. If a user adds example.com/rss you'd add example.com to the whitelist. If you expect any kind of traffic you'd probably be refreshing the RSS feeds server-side on a schedule. You could then change all the URL's to signed URL's to use with your proxy (e.g. nginx securelink, ngx_http_hmac_secure_link_module and multiple other modules for nginx).
- shadowfaxRodeo 6y ago
  Thank you. I don't fully understand your answer. But i'll do some research until I do.
rukshn 6y ago
Yes the best thing is to create a list of blacklisted domains, and don’t allow users to add a blacklisted domain. Btw is rss a thing now? I was having an idea of creating an rss reader, but gave up because rss is almost dead, Shoot me an email love to hear from you, arkruka@gmail.com
- susam 6y ago
  > Btw is rss a thing now? I was having an idea of creating an rss reader, but gave up because rss is almost dead I provide an RSS feed for my blog at https://susam.in/ https://susam.in/ . From my access.log, I see there is a decent number of subscribers to my feed. Here is the data I could pull from it: Feedly 56 subscribers Inoreader 17 subscribers Feedbin 6 subscribers NewsBlur 4 subscribers The Old Reader 3 subscribers BazQux 2 subscribers WordPress 2 subscribers ------------------------------ Total 90 subscribers I get about 4000-6000 hits to my website on a normal day. It increases by 5 to 10 times if a post hits the HN front page but I will talk about ordinary day traffic only here. From the HTTP referer (sic) information in the logs I can see that about 30-50 of those hits have a feed reader in the referer field, that is, at least 0.5%-0.75% of the total hits are coming from users who clicked on a blog post link in their feed reader and landed on the website. It is a very small percentage but 30-50 hits per day from users consuming the feed and 90 subscribers to the feed are reasons good enough to keep the feed alive.

phillipseamore 6y ago

Usually the RSS feed is on the same domain, so you could simply whitelist automatically. If a user adds example.com/rss you'd add example.com to the whitelist. If you expect any kind of traffic you'd probably be refreshing the RSS feeds server-side on a schedule. You could then change all the URL's to signed URL's to use with your proxy (e.g. nginx securelink, ngx_http_hmac_secure_link_module and multiple other modules for nginx).

shadowfaxRodeo 6y ago
Thank you. I don't fully understand your answer. But i'll do some research until I do.

rukshn 6y ago

Yes the best thing is to create a list of blacklisted domains, and don’t allow users to add a blacklisted domain. Btw is rss a thing now? I was having an idea of creating an rss reader, but gave up because rss is almost dead, Shoot me an email love to hear from you, arkruka@gmail.com

susam 6y ago
> Btw is rss a thing now? I was having an idea of creating an rss reader, but gave up because rss is almost dead I provide an RSS feed for my blog at https://susam.in/ https://susam.in/ . From my access.log, I see there is a decent number of subscribers to my feed. Here is the data I could pull from it: Feedly 56 subscribers Inoreader 17 subscribers Feedbin 6 subscribers NewsBlur 4 subscribers The Old Reader 3 subscribers BazQux 2 subscribers WordPress 2 subscribers ------------------------------ Total 90 subscribers I get about 4000-6000 hits to my website on a normal day. It increases by 5 to 10 times if a post hits the HN front page but I will talk about ordinary day traffic only here. From the HTTP referer (sic) information in the logs I can see that about 30-50 of those hits have a feed reader in the referer field, that is, at least 0.5%-0.75% of the total hits are coming from users who clicked on a blog post link in their feed reader and landed on the website. It is a very small percentage but 30-50 hits per day from users consuming the feed and 90 subscribers to the feed are reasons good enough to keep the feed alive.