You saw AS13335 on an IP and want to know what it is. AS13335 is Cloudflare's autonomous system, the network behind its CDN and security edge. Because Cloudflare sits in front of a large share of the web, this ASN behaves differently from a normal hosting network, and this page explains how.
What is AS13335?
AS13335 is the Autonomous System Number operated by Cloudflare. It carries Cloudflare's global content-delivery and security network, which proxies traffic for millions of websites. A route from AS13335 means the IP is a Cloudflare edge address. For the concept, see what an ASN is.
- ASN: AS13335
- Operator: Cloudflare, Inc.
- Type: CDN / edge network
- Behavior: acts as a reverse proxy in front of customer sites
What runs on AS13335?
Cloudflare's edge servers. When a site uses Cloudflare, visitor traffic hits a Cloudflare IP in AS13335 first, and Cloudflare forwards it to the origin server. That means AS13335 addresses front an enormous number of unrelated websites rather than hosting them directly.
Why AS13335 is a special case
Because Cloudflare is a reverse proxy, an AS13335 IP in your logs often represents Cloudflare relaying a real user, not the user's own address. If you are behind Cloudflare, the visitor's true IP arrives in a header such as CF-Connecting-IP, and that is the address you should score, not the AS13335 edge IP. Treating the Cloudflare IP as the client would misjudge every visitor.
Should you block AS13335?
Almost never. Blocking Cloudflare edge IPs can break access to a huge portion of the web and, if you sit behind Cloudflare yourself, block your own legitimate visitors. The right move is to read the real client IP from Cloudflare's forwarded header and score that instead.
How to check an IP against AS13335
To confirm an IP is Cloudflare, look up its ASN. Abstract's free ASN Lookup tool returns the ASN and operator for any address. In production, extract the real visitor IP from Cloudflare's forwarded header, then pass that to the IP Intelligence API to get its ASN and risk flags. Scoring the forwarded client IP, not the AS13335 edge IP, is what makes bot detection accurate behind a CDN.
Frequently Asked Questions
What is AS13335?
AS13335 is the Autonomous System Number operated by Cloudflare. It carries Cloudflare's CDN and edge network, which proxies traffic for millions of sites.
Why do I see Cloudflare IPs in my logs?
If a site uses Cloudflare, visitor traffic passes through Cloudflare edge IPs in AS13335 before reaching the origin. So these addresses front many sites rather than hosting them.
Is an AS13335 IP the real visitor?
Often not. When traffic is proxied through Cloudflare, the edge IP is Cloudflare's; the real client IP arrives in a header like CF-Connecting-IP, which is the address you should score.
Should I block AS13335?
No. Blocking Cloudflare edge IPs can break access to much of the web and to your own site if it sits behind Cloudflare. Read the forwarded client IP instead.
How do I check if an IP is Cloudflare?
Enter the IP into Abstract's ASN Lookup tool or call the IP Intelligence API to confirm whether its ASN is AS13335.
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