Black & White Lists

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Black & White Lists

The first DNS based blacklists, sometimes referred to as real-time black lists (RBLs), started listing the IP addresses of junk mail and virus sources from open relay mail servers, compromised hosts, and infected user workstations. There are also blacklist lists for bogus domain names of web and mail addresses found in mail detritus. Originally, these services started off as community projects that collected information from "spam" traps and have evolved into valuable services in the effort to combat junk mail, scams, identity theft, and malware.

There are several DNS-based black and white list services freely and/or commercially available. Almost all are free for a low volume of DNS queries from their public feeds, but if the volume surpasses a service's threshold they will typically cut off individual organisations, insisting they subscribe to private commercial feeds. Spamhaus is one of the oldest and most respected of these services providing both IP and domain black/white lists. Also SURBL and URIBL are well-respected domain blacklist services.

References