Detecting Brute-Force and Dictionary attacks

Hi All, I am looking for a good tool to detect brute-force and dictionary attacks on user accounts on a Linux system . The tool should also have the intelligence to differntiate between user mistakes and actual brute-force/dictionary attacks and reduce the false positives. SLES9/SLES10 included security tools are not helping in this case . The seccheck package functionality also not matching with my requirement. Please , anyone knows any third party security tool or any opensource security tool which solves my problem ? Thanks & Regards, Shashi Kanth,CISSP