A simple program that can be used as a login shell, which sends a POST query to a server containing a (short) challenge that is asked back to the user. Intended to be sending a text message challenge through APIs.
Postjail is configured in .postjailrc, which should be in the working
directory in which postjail will be invoked (probably the home of the user).
The syntax is a very basic one: each line matches \w*[^=]*\w*=\w*[^=]*\w*,
where \w = [ \t\n], that is, a tag and a value separated by an = sign,
possibly surrounded by whitespaces.
The tag may be one of the following:
url: the address that must be called to send the challenge;http_header: any header you might want to specify in the HTTP request (e.g.,Content-Type);post_headerandpost_footer: the text that surrounds the challenge string in the POST request;on_success: the program (not command!) to invoke on success;challenge_length: an integer specifying the challenge length;cooldown_time: the number of seconds that must ellapse between a failed authentication and the next authentication try.
A line is considered to be a comment (and thus ignored) if its first character
is a #.
This is an example of configuration file:
url = https://example.com/query_url
http_header = Content-Type: application/json
post_header = { "challenge":"
post_footer = " }
on_success = /bin/bash
challenge_length = 8
cooldown_time = 300
# 5 minutes cooldown time