Digital postmark
From Wikipedia, the free encyclopedia
A digital postmark is a network security mechanism, developed by Penn State researchers, Ihab Hamadeh and George Kesidis, to identify which region, a packet or a set of packets comes from. It was developed as a way to combat spam and denial-of-service (virus) attacks, by isolating the source of such attacks, while still allowing "good" messages to pass through.
A digital postmark works when a perimeter router marks up a packet border with its region-identifying data. Also called a "border router packet marking", it uses an obsolete or unused portion of the packet to place the regional mark-up. When room does not exist in any one portion of the packet, the region information can be broken up and hashed in a subsequently retrievable way.
