BLD is a blacklist daemon designed to function as a blacklist server.
The primary purpose of BLD is to fight against dictionary-based spam by making the MTA report to BLD any host that attempts to send an email to an unknown user. However, it is also suitable for use by any program. It is essential to use BLD in a safe environment, as access control is based on clients' IP addresses. By default, BLD binds to localhost and should not accept requests from a machine where non-trusted users can log in or establish network connections via other means, such as PHP.
The BLD software application works by receiving insertion requests to add an address to the list, submissions to add an address if the submission rate is too high, queries to ask if an address is blacklisted, or decrements to decrease the internal counter of submissions for an IP. It uses a straightforward algorithm to decide whether to add submitted IP addresses to the blacklist or not. The first time an IP address is submitted, it is added to an internal list with a timestamp, and all further requests increment a counter for this IP.
When the minimum time interval is elapsed (default: 30 seconds), and if a maximum request ratio is reached (default: 10 submissions in the 30 seconds interval), the IP is put in the blacklist. It is then blacklisted for a configurable time (default: 900 seconds).
This recently updated release of BLD includes minor improvements such as typo fixes, removal of obsolete utilities, and links to the new primary website.
Version 0.3.4.1: N/A