If your post contains "etc hosts" with slashes then you are temporarily blocked.
Confirmed. You should PM theymos:
Next time it happens, click the back button, copy exactly what you were trying to post, put it on pastebin, and send me the link.
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Whenever this happens, feel free to obfuscate the post in order to bypass Cloudflare's blocking until I'm able to fix it permanently.
Click to read the full post and context.