flask-Captchaify 1.6.9.4.1

Protect against bots and DDoS attacks

A DDoS defense system for flask applications, first sends users to a captcha page without a javascript script and creates a confirmation cookie/url arg after the captcha.

Caution: Captchaify must now no longer be imported as Captcha, i.e. from flask_Captchaify import Captcha, but as Captchaify (from flask_Captchaify import Captchaify)

The normal captcha page has changed and from version 1.6.8 uses a one-click method instead of text captchas, use the default_captcha_type argument to set the captcha with text back to text

Todos:

• Captcha type with multiclick
• Captcha data set with animals
• Add used captcha id to text captcha
• Captcha data set with emojis
• Captcha or blocking rules based on client_ip and client_ip_info (e.g. blocking of certain IP countries)

How does flask_Captchaify work?

If needed, a captcha is displayed to the user (or the robot) based on the strength set. Javascript is not needed for this, as the content is rendered on the server. If the captcha is fulfilled correctly, a token is created that stores the client's data in encrypted form and is used to confirm fulfillment with each request. It is stored as a cookie and as the url Arg captcha.

Tip: The captcha, language and theme Arg is automatically inserted in all anchors on your HTML page

An example script could look like this:

from flask import Flask
from flask_Captchaify import Captchaify

app = Flask(__name__)
captchaify = Captchaify(app, default_action = "fight")

@app.route("/")
def index():
    return 'Hello Human!'

if __name__ == "__main__":
    app.run(host = "localhost", port = 8080)

Application purposes

A few application purposes:

• Protect against DDoS attacks
• Your website contains content that should not be read by a robot
• A login website
• A dark web page

Why should you use Captchaify if you host a Flask server?

A quick and easy implementation allows even small websites or a small team of developers to quickly get bot protection. It also doesn't use third-party providers, which limits data collection from Google, Facebook and the creepy data brokers. Everything is open source, meaning you can rewrite the code yourself and perhaps make it more private.

Instructions

Installation guide

1. Make sure you have the latest version of Python and Pip installed, you also need git installed.
2. Install the script with pip pip install flask_Captchaify or manually via git clone https://github.com/tn3w/flask_Captchaify or download the zip.
3. If you installed it manually, make sure your python script is in the folder where there is a subfolder flask_Captchaify, and make sure you run pip install -r requirements.txt in the flask_Captchaify folder.
4. Make sure that after:

   app = Flask(__name__)
   

   You add the line:

   captchaify = Captchaify(app, default_action = "fight")
   

   And at the beginning of the file add the import:

   from flask_Captchaify import Captchaify
   

For more information, see the sample code above.

Personalization

1. app Arg

   A Flask() object of a Flask app that is modified by Captchaify so that each request is checked for bots

   Example:

   from flask import Flask
   from flask_Captchaify import Captchaify
   
   app = Flask('MyWebsite')
   captchaify = Captchaify(app)
   

2. captcha_types Arg

   To change the captcha type in the case of certain routes / endpoints, you can use the captcha_types parameter.

   Example of a website that uses an oneclick captcha on the main page and enforces text captchas on the login page.

   captchaify = Captchaify(app, captcha_types={"/": "oneclick", "/login": "text"})
   

   When using "*" before or after the urlpath / endpoint you can address multiple urls. "*" means every possible letter / number or special character.

   Example of a website where all urls with "/dev/" e.g. /account/dev/settings or /dev/portal are using oneclick captchas, all urls starting with "/login" e.g. /login or /login/2fa displays an text based captcha and all urls ending with "/register/" e.g. /register or /game/register have oneclick captchas:

   captchaify = Captchaify(app, captcha_types={"*/dev/*": "oneclick", "/login*": "text", "*/register": "oneclick"})
   

   All captcha types:

   Name of captcha type	Displayed Captchas
   oneclick (Default)	The user only needs one click to confirm that he is not a bot
   multiclick	The user must select several images that match a motif (harder)
   text	The user enters a text combination from an image into an input (obsolete)

   To specify the exact data set, you have to add it after the captcha_type with a _ as separator, e.g. oneclick_animals or if you use a custom data set: oneclick_custom. If you use a text captcha, you do not need a data set.

   Here are all the ready-made data sets:

   Name of dataset	Displayed Captchas
   keys	Displays images based on specific keywords of landscapes, objects, and more (default for oneclick)
   animals	Displays 50 different animal species (default for multiclick)

3. dataset_size Arg

   The size of the data set with e.g. images and keywords that determine how much of a data set is used, if a lot is used this can reduce RAM capacity but also increase security. Either a tuple of 2 numbers where the first indicates how many images per keyword (always the first ones) can be used (recommended around 20, maximum 200 or more depending on the data set) and the second number how many keywords are e.g. (images_per_keyword, number_of_keywords), default setting: (20, 100).

   But can also be a string for prefabricated dimensions:

   value	corresponding tuple
   largest	(200, 140)
   large	(20, 140)
   medium	(100, 100)
   normal (default)	(20, 100)
   small	(20, 36)
   smaller	(20, 8)
   little	(6, 8)

   The more images per keyword, the more inaccurate the user rate becomes, as images further behind in the image search and in the data set could no longer show the keyword. It is recommended that you generate your own dataset as the default data could be trained, use the script written in src/flask_Captchaify/datasets and put the file in a folder and use the dataset_dir Arg to use it.

   Example of a website that uses 100 images per keyword and 140 keywords:

   captchaify = Captchaify(app, dataset_size=(100, 140))
   

4. dataset_dir Arg

   Specifies where the program can find data sets.

   Example of a website that specifies its own dataset folder:

   captchaify = Captchaify(app, dataset_dir='/path/to/my/dataset')
   

   A data set should be a json file and have the following names in the folder:

   dataset_dir\
          \keys.json
   

5. actions Arg

   To change the response in the case of certain routes / endpoints, you can use the actions parameter.

   Example of a website that allows all bots on the main page, enforces captchas on the login page, and blocks all robots on the registration page:

   captchaify = Captchaify(app, actions={"/": "let", "/login": "fight", "/register": "block"})
   

   When using "*" before or after the urlpath / endpoint you can address multiple urls. "*" means every possible letter / number or special character.

   Example of a website where all urls with /api/ are allowed through, all urls starting with "/dogs/" show everyone a captcha and all urls ending with "/cats/" block bots:

   captchaify = Captchaify(app, actions={"*/api/*": "let", "/dogs/*": "fight", "*/cats/": "block"})
   

   All actions:

   Name of action	Executing Action
   let	Allows all traffic through, regardless of whether the IP is blocked.
   block	Blocks all traffic if it is blocked, without captcha.
   fight	Displays a captcha to all traffic, whether suspicious or not.
   captcha	Default value, shows only suspicious traffic captchas.

6. hardness Arg

   To change the hardness of a captcha for specific routes or endpoints use hardness.

   Example of a website that sets the hardness of the main page to 1 (= easy), on the login page to 2 (= normal) and on the register page to 3 (= hard):

   captchaify = Captchaify(app, hardness={"/": 1, "/login": 2, "/register": 3})
   

   When using "*" before or after the urlpath / endpoint you can address multiple urls, like actions.

   All hardness levels:

   Hardness Level	Captcha modification
   1	The captcha is easy. Only a text captcha with 6 - 8 characters is displayed
   2	The captcha is normal. Only a text captcha with 9 - 11 characters is displayed
   3	The hardness of the captcha is hard, a 9 - 14 number audio captcha is displayed in addition to the 10 - 12 character text captcha.

7. rate_limits Arg

   To change the rate_limit and max_rate_limit for a specific route or endpoint use the rate_limits arg.

   When using "*" before or after the urlpath / endpoint you can address multiple urls, like actions.

   The syntax is a bit different from the others, because two values are specified {"route": (rate_limit, max_rate_limit), "endpoint": (rate_limit, max_rate_limit)}. The variable rate_limit must be a number indicating how many requests per minute can come from a given ip. max_rate_limit indicates how many requests can come from all ips per minute, also a number.

   Example of a website that has a specific rate_limit on /api/:

   captchaify = Captchaify(app, template_dirs={"/api/*": (60, 600)})
   

8. template_dirs Arg

   To change the template directory of a particular route use the template_dirs arg.

   Example of a website that has a specific template directory on /api/:

   captchaify = Captchaify(app, template_dirs={"/api/*": "/path/to/special/template/directory"})
   

   When using "*" before or after the urlpath / endpoint you can address multiple urls, like actions.

   A template directory can look like this:

   template_directory\
              \captcha_text.html
              \captcha_oneclick.html
              \captcha_multiclick.html
              \block.html
              \rate_limited.html
              \change_language.html
   

   If one of the three templates does not exist in the folder, a 404 error is displayed when calling it. e.g. if you remove the changelanguage page at apis.

9. default_captcha_type Arg

   To specify the default captcha type of all routes or endpoints use the default_captcha_type arg.

   Example of a website that has set its types to "text" (for text bases captchas) for all routes:

   captchaify = Captchaify(app, default_captcha_type="text")
   

10. default_action Arg

    To specify the default action of all routes or endpoints use the default_action arg.

    Example of a very paranoid website that has set its action to "fight" for all routes:

    captchaify = Captchaify(app, default_action="fight")
    

11. default_hardness Arg

    To specify the default hardness of all routes or endpoints use the default_hardness arg.

    Example of a very paranoid website that has set its hardness to 3 (= hard) for all routes:

    captchaify = Captchaify(app, default_hardness=3)
    

12. default_rate_limit Arg

    To specify the default requests of an IP per minute for all routes use the default_rate_limit variable. (Default: 120 = 2 requests per second per IP)

    Example of a web page with custom rate_limit:

    captchaify = Captchaify(app, default_rate_limit=60)
    

13. default_max_rate_limit Arg

    To specify the default requests of all IPs per minute for all routes use the default_max_rate_limit variable. (Default: 1200 = 2 requests per second from 10 IPs)

    Example of a web page with custom max_rate_limit:

    captchaify = Captchaify(app, default_max_rate_limit=600)
    

14. default_template_dir Arg

    To specify the default template_dir of all routes or endpoints use the default_template_dir arg.

    Example of a web page with custom template_dir:

    captchaify = Captchaify(app, default_template_dir="/path/to/my/custom/template/directory")
    

15. verification_age Arg

    Indicates the time in seconds how long a solved captcha is valid (Default: 3600 = 1 hour)

    Website with 3 hours verification_age:

    captchaify = Captchaify(app, verification_age=10800)
    

16. without_cookies Arg

    If True, no cookies are created, and verification is proven via URL args (Default: False)

    Website with without_cookies enabled:

    captchaify = Captchaify(app, without_cookies=True)
    

17. block_crawler Arg

    If True, crawlers like Googlebot, further are estimated via their user agent as suspicious and not the website, good for websites that should not be crawled (Default: True)

    Web page with block_crawler enabled:

    captchaify = Captchaify(app, block_crawler=True)
    

18. crawler_hints Arg:

    If True, crawlers like Googlebot, are shown meta tags and the title of a normal web page, while they would have to solve a captcha. (Default: True)

    Web page with crawler_hints disabled:

    captchaify = Captchaify(app, crawler_hints=False)
    

19. third_parties Arg:

    Specifies which third parties are used to check the IP addresses. By default, all 3 third parties are used. (See list)

    Web page that only asks a third party for Tor Ip addresses:

    captchaify = Captchaify(app, third_parties=["tor"])
    

    Possible entries would be:

    Abbreviation	Who is requested and how does the evaluation mechanism work?
    tor	SecOps-Institute/Tor-IP-Addresses on GitHub is asked for Tor Ipv4 and Ipv6 addresses and the Ip address is compared with this list
    ipapi	Ipapi is requested with the Ip and the result of the fields "proxy" and "hosting" is used
    stopforumspam	StopForumSpam is requested and the result is used

20. as_route Arg:

    Specifies whether Captchaify pages are displayed as separate routes in order not to confuse the cache between normal pages and Captchaify pages (e.g. for Cloudflare)

    Web page where this is activated:

    captchaify = Captchaify(app, as_route = True)
    

21. without_other_args Arg:

    After solving the captcha, arguments such as language and theme are deleted from the url bar

    Web page where this is activated:

    captchaify = Captchaify(app, without_other_args = True)