> [...] blocking of only a few IPs is disproportionately effective at stopping brute force SSH attacks here. Also, since we already block Internet logins to 'ro

> [...] blocking of only a few IPs is disproportionately effective at stopping brute force SSH attacks here. Also, since we already block Internet logins to 'root', we're in almost no danger. No matter how many times they try, they have literally no chance of success. This assumes OpenSSH, OpenSSL and other things in between the client and the server don't have ready to exploit security vulnerabilities. These large-scale scanners are a long term investment when there's a zero-day vulnerability to exploit in OpenSSL etc. That's why a layered/defense-in-depth approach is preferable.