Spammers and phishers, for example, are generally considered bad guys. By contrast, well known, well behaved sources of mail and web site providers, like AOL or GMail, are considered good guys.
There are hundreds of entities on the Internet that try to keep track of good and bad actors. Some are quite well known. TRUSTe operates an accreditation process which certifies good websites. Spamhaus investigates spammers and keeps track of suspect IP ranges. Phishtank is a community for people to report phishing URLs.
Less well known are several hundred DNSBLs of varying reliability and respectability.
For convenience, we lump all of these entities together under the label "publishers". Publishers make data available as "feeds".
Many publishers make their feeds available in bulk over rsync or http. Karmasphere regularly "syndicates" them from the source. Where necessary, Karmasphere negotiates a license or contract. The system also enables users to publish their own feed via the web site.
Having amassed all this data, Karmasphere gives users the ability to use particular combinations of feeds called "feedsets". Some starting point feedsets are provided by Karmasphere. Users can build their own feedsets too and even share them with others.
To reduce query latency, folks like to cache the data locally: this is why many DNSBLs offer an rbldsnd zone file. But mirroring a zone file introduces replication latency, because you can only pull the snapshot once every hour, or day; anything more frequent would overload the source.
Karmasphere solves this problem by providing a network of replication servers which take data from upstream nodes, pass it along to downstream nodes, and answers queries from cilents to boot.
Because the replication protocol is push-based, end-to-end latency is minimized.
Nodes can even reside at local data centers right next to the services that query them, reducing query latency to an minimum.
The reputation of an identity is queried either via our web site, or over the network. Karmasphere "clients" use a variety of protocols to request the reputation score of one or more identities. We support many MTAs, many plugins, many protocols.
