badbots
Current CIDR-formatted list of unwanted bots caught on my systems, updated hourly.
Bad Bots
These contain hacking attempts, probing, scanning, impersonating search engines and lots more. As only manually curated filters trigger a listing, this should be safe to use.
Email Spam Bots
Spam senders, especially those with an unusually high SpamAssassin score (15+).
Crawlers
These contain a wide range of automated crawlers from the areas of SEO, data mining, aggressive Chinese and Russian bots, questionable security research and similar. May not be suitable for general use.
Facebook Crawler
There are now Facebook Crawler IP ranges available, generated with the instructions to be found via Facebook's webmaster documentation. Effectively it's generating what's meant to be a whitelist. You can use it as such — or the opposite.
Providers
Several large ISPs with a track record of being the origin of many attacks.
VNPT (Vietnam Posts and Telecommunications Group)
This particular state-owned telecommunications company has an ongoing problem
with spammers, break-in attempts and malware. They are either not up to the
task to contain this to a reasonable degree or they just don't care. There's
now a list of IPs caught by my systems, especially repeated attempts with that
pesky message hostname static.vnpt.vn does not resolve to address 14.169.239.162.
Probably empty since I'm blocking email from VN for the time being.
VPN
Many popular and obscure commercial VPN providers. Blocking those has effectively halved my abusive traffic.
WordPress
Any kind of WordPress-focused abuse: scanning, probing, user enumeration, XMLRPC spamming, bruteforce password attacks, you name it.