Disclaimer: I work on a search engine (findx). I try not to put competitors in a bad light.
Question: Should a web crawler always reveal its true name?
Background: While crawling the web I've found some situations where using a fake user-agent might help. First example is a web site that checks the user-agent in the http-request and returns a "your browser is not supported" - even for robots.txt. Another example is a site that had an explicit whitelist in robots.txt. Strangely, 'curl' was whitelisted but 'wget' was not. I hesitate in using a fake user-agent, e.g. googlebot because it isn't clear what the clueless webmasters' intentions are. It appears that some websites are misconfigured or so google-optimized that other/new search engines may have to resort to faking user-agent.
I'm also puzzled by Qwant because they claim to have their own search index but my personal website (which is clearly indexed when I search in qwant) has never been crawled by a user-agent resembling anything that could lead to qwant. Apparently they don't reveal what their user-agent is: https://blog.qwant.com/qwant-fr/. And there has been some discussion about it: https://www.webmasterworld.com/search_engine_spiders/4743502.htm
This is different from search engines that don't have their own index (eg. DuckDuckGo uses results from Yahoo! and yandex. Startpage uses Google, etc.)
So what do you Soylentils say, is faking the user-agent in webcrawls necessary? Acceptable? A necessary evil?
(Score: 2) by darkfeline on Tuesday July 05 2016, @03:35PM
>Heck, you could simply omit the user-agent as it's not a required header in RFC7231.
You COULD, but you shouldn't.
The point of the user agent is to identify your client so bugs can be tracked down to the right source. For example, if I notice a huge torrent of traffic with the user agent lib version 1.2, I can tell you about it and then you can go and look, and discover a bug where if settings A and B are set, it will infinite loop.
The point is NOT to vary the content based on the user agent's supported feature set. HTTP already has a method for content negotiation: the Accept header.
Nowadays the user agent header is fucking useless since everyone just sends the same few variations of Mozilla/5.0.
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