What is gld-ng ?

gld-ng stands for GreyList Daemon, new generation. gld-ng is a standalone policy delegation server for postfix that implements greylisting.

It is based on the GLD project, originated by Salim Gasmi.

What makes gld-ng different from other greylisting servers ?

gld-ng implements the author’s vision of the ideal greylisting daemon. Obviously, this may or my not suit your needs.

Over the years, the author has used a variety of greylisting daemons. All had different shortcomings. Which is why he tried to come up with his own. The basic design requirements were the following:

• It should handle IPv6 connections: with the complete exhaustion of IPv4 addresses arriving soon, mail servers will need to support IPv6. Unfortunately, spambots will adapt, too. Hence, the greylistying daemon needs to support IPv6.

• It should have a small memory footprint: let’s face it, greylisting should not be using your server’s memory too much. Daemons written in interpreted languages, like Perl, tend to use quite a lot of memory. This one is written in C.

• It should use a database: While reviewing possible databases for this project, we settled with PostgreSQL. The main reason is that PGSQL is unique in the way it can handle IP addresses. It does feature data types for IP address and CIDR ranges and has specific operators to work with them. Because it is network-based, the database can be shared among multiple mail servers, making it scalable. This is not to say that MySQL, SQLite or other databases are bad. However, PGSQL fits our needs best.

What are the requirements ?

gld-ng needs the following software:

• a postfix 2.1 or higher server

• a PostgreSQL server