Doesn't ask for robots.txt and does this crazy probe:
83.169.26.5 "GET / HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /index.php HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /default.php HTTP/1.1""RankFlex.com Webspider"
83.169.26.5 "GET /index.html HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /index.htm HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /default.htm HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /default.html HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /index.jsp HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /default.jsp HTTP/1.1" "RankFlex.com Webspider"
83.169.26.5 "GET /rankflex_content_duplication_test HTTP/1.1" "RankFlex.com Webspider"
crawls from vwp4525.webpack.hosteurope.de