/usr/include/libktorrent/dht/ is in libktorrent-dev 1.3.1-5build2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libktorrent/dht/announcereq.h
/usr/include/libktorrent/dht/announcersp.h
/usr/include/libktorrent/dht/announcetask.h
/usr/include/libktorrent/dht/database.h
/usr/include/libktorrent/dht/dht.h
/usr/include/libktorrent/dht/dhtbase.h
/usr/include/libktorrent/dht/dhtpeersource.h
/usr/include/libktorrent/dht/findnodereq.h
/usr/include/libktorrent/dht/findnodersp.h
/usr/include/libktorrent/dht/getpeersreq.h
/usr/include/libktorrent/dht/getpeersrsp.h
/usr/include/libktorrent/dht/kbucket.h
/usr/include/libktorrent/dht/kbucketentry.h
/usr/include/libktorrent/dht/kbuckettable.h
/usr/include/libktorrent/dht/kclosestnodessearch.h
/usr/include/libktorrent/dht/key.h
/usr/include/libktorrent/dht/node.h
/usr/include/libktorrent/dht/nodelookup.h
/usr/include/libktorrent/dht/pack.h
/usr/include/libktorrent/dht/pingreq.h
/usr/include/libktorrent/dht/pingrsp.h
/usr/include/libktorrent/dht/rpccall.h
/usr/include/libktorrent/dht/rpcmsg.h
/usr/include/libktorrent/dht/rpcmsgfactory.h
/usr/include/libktorrent/dht/rpcserver.h
/usr/include/libktorrent/dht/rpcserverinterface.h
/usr/include/libktorrent/dht/task.h
/usr/include/libktorrent/dht/taskmanager.h