Blocklists · Answer to why why popular IPs like 1.1.1.1 end up in blocklists.
Source Reddit Cybersecurity
Discussion
This report discusses why popular IP addresses such as Cloudflare's 1.1.1.1 and Google's 8.8.8.8 sometimes appear on blocklists. The reason is that these IPs may generate traffic on non-standard ports or perform network activities like ICMP pings that sensors monitoring for abuse interpret as suspicious. The post provides examples of IPs hitting unusual destination ports or scanning behavior, which can cause them to be flagged and added to blocklists despite being legitimate services. No direct vulnerability or exploit is described.
r/cybersecurity (opens in a new tab)u/Tall-Bonus-68500 points0 comments
As I monitor logs vs known hosts of interest (monitor for abuse)
Many blocklists end up with DNS IP like cloudflare 1.1.1.1 and google 8.8.8.8 and others... here is why in output below...
1.1.1.1 as example is hitting non standard ports against our sensor!
8.8.8.8 as example has icmp ping our sensor! (sensor is a dynamic IP changing weekly, so active scanning for responsive icmp listening hosts across subnets on 8.8.8.8 is also odd - end up in blocklists easily!)
5.255.126.112 as second example over time is reused for different web crawlers but shows it is only accessing genuine service ports for its intended purpose.
If someone at u/cloudflare can tell us what other roles 1.1.1.1 does other than DNS for client lookups, that be appreciated as destination ports 41765,41806,40610,41429,41243 are not common destination service ports!
# Generated: 2026-06-12 09:21:42 # # COUNT IP STATUS PORTS WHITELIST FILE(S) # ----------------------------------------------------------------------------- 56 104.29.155.123 NEW 53 asn_13335_cloudflare.txt 32 104.29.154.46 NEW 53 asn_13335_cloudflare.txt 30 162.159.130.233 NEW 53 asn_13335_cloudflare.txt 29 104.29.147.78 NEW 53 asn_13335_cloudflare.txt 26 188.114.97.2 NEW 53 asn_13335_cloudflare.txt 24 172.67.202.238 NEW 53 asn_13335_cloudflare.txt 21 104.29.152.123 NEW 53 asn_13335_cloudflare.txt 20 104.29.146.123 NEW 53 asn_13335_cloudflare.txt 16 104.28.162.227 NEW 37777 asn_13335_cloudflare.txt 11 104.28.162.113 NEW 53 asn_13335_cloudflare.txt 10 66.249.77.96 NEW 80 webcrawler_googlebot_ip_list.txt 10 172.65.254.112 NEW 53 asn_13335_cloudflare.txt 9 104.29.154.113 NEW 53 asn_13335_cloudflare.txt 8 104.28.165.160 NEW 22 asn_13335_cloudflare.txt 8 172.70.251.62 NEW 443 asn_13335_cloudflare.txt 7 104.29.140.5 NEW 53 asn_13335_cloudflare.txt 6 5.255.126.112 NEW 443,80 webcrawler_ClaudeBot_ip_list.txt,webcrawler_bingbot_ip_list.txt,webcrawler_googlebot_ip_list.txt,webcrawler_gptbot_ip_list.txt,webcrawler_openai_ip_list.txt 6 88.151.32.61 NEW 443,80 webcrawler_ClaudeBot_ip_list.txt,webcrawler_bingbot_ip_list.txt,webcrawler_googlebot_ip_list.txt,webcrawler_openai_ip_list.txt 6 88.151.34.250 NEW 443,80 webcrawler_ClaudeBot_ip_list.txt,webcrawler_bingbot_ip_list.txt,webcrawler_googlebot_ip_list.txt,webcrawler_gptbot_ip_list.txt,webcrawler_openai_ip_list.txt 6 208.84.101.224 NEW 80,443 webcrawler_ClaudeBot_ip_list.txt,webcrawler_bingbot_ip_list.txt,webcrawler_googlebot_ip_list.txt,webcrawler_openai_ip_list.txt 5 1.1.1.1 REPEAT 41765,41806,40610,41429,41243 asn_13335_cloudflare.txt,dns_cloudflare.txt 4 104.29.156.127 NEW 44493,36547 asn_13335_cloudflare.txt 3 1.0.0.1 REPEAT 41263,41054,40572 asn_13335_cloudflare.txt 3 8.8.8.8 NEW 0 dns_google.txt 3 104.29.147.76 NEW 48683 asn_13335_cloudflare.txt 3 104.29.159.117 NEW 57162,63118,35753 asn_13335_cloudflare.txt 2 104.29.146.40 NEW 63581,45422 asn_13335_cloudflare.txt 2 104.29.151.115 NEW 56248,62277 asn_13335_cloudflare.txt 2 104.29.153.182 NEW 61430 asn_13335_cloudflare.txt 1 23.227.39.200 NEW 64406 asn_13335_cloudflare.txt 1 104.18.41.41 NEW 57483 asn_13335_cloudflare.txt 1 104.29.132.91 NEW 51221 asn_13335_cloudflare.txt 1 104.29.141.234 NEW 54025 asn_13335_cloudflare.txt 1 104.29.147.217 NEW 44555 asn_13335_cloudflare.txt 1 104.29.153.183 NEW 43680 asn_13335_cloudflare.txt 1 104.29.159.122 NEW 34964 asn_13335_cloudflare.txt 1 172.64.154.50 NEW 64752 asn_13335_cloudflare.txt