Something one can do against an IP beeing used for attacks?

Hi there, found lots of this in my log: Dec 9 14:58:50 encoco sshd[27696]: connect from root@IP Dec 9 14:58:50 encoco sshd[27696]: log: Connection from IP port 3756 Dec 9 14:58:50 encoco sshd[27696]: log: Could not reverse map address IP. Dec 9 14:59:00 encoco sshd[27696]: fatal: Local: crc32 compensation attack: network attack detected I have changed IP in above. Something one can do against this IP beeing used for attacks? Or, uncover the person behind? regards Rowald