Internet　purification　is　a　necessary　technique　to　defend　against　Distributed　Denial-of-Service　(DDoS)　attack.　It　can　help　Internet　Service　Provider　(ISP)　to　completely　and　precisely　scrub　attack　traffic　through　establishing　the　sender-receiver　pair　based　filtering　rules　in　networks.　However,　when　faced　with　the　Link　Flooding　Attacks　(LFA),　a　new　kind　of　DDoS,　existing　relevant　schemes　suffer　the　drawbacks,　including　the　weak　willingness　of　defense　cooperation　between　Autonomous　Systems　(ASes),　lower　filtering　efficiency　and　poor　robustness.　For　this,　we　propose　STOP,　a　service-oriented　Internet　purification　technique　designed　to　defend　against　LFA.　In　STOP,　malicious　traffic　filtering　is　viewed　as　a　value-added　service　and　each　filter　contributor　(i.e.,　AS)　can　get　some　benefit　from　it.　This　helps　ASes　to　strengthen　the　willing　of　defense　cooperation.　Moreover,　we　devise　a　filter　recommendation　algorithm　to　maximize　the　filtering　efficiency,　with　minimum　service　cost　and　bandwidth　damages.　Furthermore,　in　the　face　of　the　strategic　threats　that　aim　to　paralyze　or　bypass　STOP,　we　devise　relevant　defense　techniques　to　make　it　more　robust.　Through　rigorous　mathematical　analysis　and　extensive　experiments　based　on　real-world　topology,　we　demonstrate　that　compared　with　prior　work,　STOP　increases　the　filtering　efficiency　by　12%.　©　2005-2012　IEEE.