Stories
Slash Boxes
Comments

SoylentNews is people

Web Crawler User-Agent: Genuine or Fake?

posted by martyb on Tuesday July 05 2016, @10:51AM   Printer-friendly
from the what-would-you-do? dept.

isj writes:

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?

Original Submission

 
This discussion has been archived. No new comments can be posted.
Web Crawler User-Agent: Genuine or Fake? | Log In/Create an Account | Top | 63 comments | Search Discussion
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.

  • (Score: 0) by Anonymous Coward on Tuesday July 05 2016, @06:12PM

    by Anonymous Coward on Tuesday July 05 2016, @06:12PM (#370180)

    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.

    1: Spoof a current version of a common browser (so, Firefox). 2: go in if wget or curl are allowed in robots.txt, respect it to the letter otherwise. 3: in particular, don't go in if it only allows googlebot.
    4: If you want, append your bot's name to the end.

    the rationale for these is
    1: poorly configured sites are increasingly common, being "Firefox" lets you get at the site as it was intended to be displayed
    2: wget and curl can scrape a whole site, if a site allows them at all, there isn't a rationale for other bots being blocked (particularly since there's quite a few that use wget/curl to do their work, so their UA string will be wget or curl's)
    3: if a site only allows googlebot, they'll probably block anything else scraping, so just go with what it says
    4: this may/may not override 1 -- some misconfigured sites will probably balk at the addition, but it allows you to be specifically whitelisted/blacklisted