Hello,

which site to use to report bad IP (spammer, exploiter, ddos)?

I found following services so far:
https://www.abuseipdb.com (download whole large blacklist database link: https://www.abuseipdb[d0t]com/blocklist)
https://myip.ms/browse/blacklist/Bla...base_Real-time (registration needed)
https://www.badips.com
http://stopforumspam.com (SPAM only DB)
https://iplists.firehol.org (can not report IP, just source of many IP blocklists)

If have evidence of an illegal activity from some IP, one can report it to the IP owner (search IP at http://myip.ms to get details and e-mail of the owner)