{"id":622,"date":"2025-11-14T16:05:36","date_gmt":"2025-11-14T22:05:36","guid":{"rendered":"https:\/\/blog.xbytecloud.com\/?p=622"},"modified":"2026-02-17T16:06:02","modified_gmt":"2026-02-17T22:06:02","slug":"why-iis-ip-restrictions-break-behind-cloudflare-and-how-to-fix-it","status":"publish","type":"post","link":"https:\/\/www.xbytecloud.com\/blog\/why-iis-ip-restrictions-break-behind-cloudflare-and-how-to-fix-it\/","title":{"rendered":"Why IIS IP Restrictions Break Behind Cloudflare (and How to Fix It)"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Locking down access by IP address is a common and effective security practice. On Windows servers running IIS, the <strong>IP Address and Domain Restrictions<\/strong> feature has long been the go-to tool for allowing or denying traffic at the server or site level.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">But if your site sits behind <strong>Cloudflare<\/strong>, that familiar approach can suddenly\u2014and confusingly\u2014stop working.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Here\u2019s why it happens, what\u2019s really going on under the hood, and how to do it <em>the right way<\/em>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>The Problem: \u201cI Allowed My IP\u2026 Why Am I Getting 403 Forbidden?\u201d<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A customer recently ran into this exact issue:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>They configured IIS to <strong>allow only specific IPv4 addresses<\/strong><\/li>\n\n\n\n<li>The rule was applied at the <strong>server level<\/strong><\/li>\n\n\n\n<li>Their own IP address was explicitly allowed<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Yet every request resulted in a <strong>403 Forbidden<\/strong> error\u2014even when browsing directly from the allowed IP.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If you\u2019ve ever stared at IIS convinced <em>you didn\u2019t misconfigure anything<\/em>, you\u2019re probably right.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>ColdFusion + IIS + Cloudflare: Why This Matters Even More<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If you\u2019re running <strong>Adobe ColdFusion<\/strong> on IIS, this issue isn\u2019t just academic\u2014it\u2019s operational.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ColdFusion applications frequently expose:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Internal APIs<\/li>\n\n\n\n<li>Scheduled tasks<\/li>\n\n\n\n<li>Legacy endpoints that were never designed for public access<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Many ColdFusion teams rely on <strong>IIS IP Address and Domain Restrictions<\/strong> as a first line of defense to protect these surfaces. When Cloudflare is added in front, that protection silently stops working\u2014often without anyone realizing it.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The result is a dangerous false assumption:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>\u201cOur ColdFusion application and internal routes are IP-restricted.\u201d<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Behind Cloudflare, they aren\u2019t\u2014unless the restriction is enforced <strong>at the Cloudflare layer<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">That\u2019s why ColdFusion environments benefit disproportionately from:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Cloudflare Security Rules for IP allow\/deny<\/li>\n\n\n\n<li>Explicit edge-level access control for admin paths<\/li>\n\n\n\n<li>Hosting providers who understand how ColdFusion, IIS, and Cloudflare interact in real deployments<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udc49 If you\u2019re running ColdFusion in production and want these controls configured correctly from day one, this is exactly what we handle with our <a href=\"https:\/\/www.xbytecloud.com\/coldfusion\/hosting\/coldfusion-cloud-hosting\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>managed ColdFusion hosting<\/strong>.<\/a><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>The Root Cause: Cloudflare Masks the Real Client IP<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When Cloudflare is enabled in <strong>proxied mode<\/strong> (the orange cloud), it acts as a reverse proxy:<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>The visitor connects to Cloudflare<\/li>\n\n\n\n<li>Cloudflare connects to your origin server<\/li>\n\n\n\n<li>IIS only sees <strong>Cloudflare\u2019s IP<\/strong>, not the visitor\u2019s<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">The visitor\u2019s real IP address is passed in a custom HTTP header:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">CF-Connecting-IP<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Here\u2019s the key issue:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>IIS IP Address and Domain Restrictions does not read HTTP headers by default.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It only evaluates the <em>source IP of the TCP connection<\/em>, which\u2014behind Cloudflare\u2014is always a Cloudflare IP.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So when you \u201callow\u201d your own IP in IIS:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>IIS never sees it<\/li>\n\n\n\n<li>The request never matches<\/li>\n\n\n\n<li>Access is denied<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This is expected behavior, not a bug.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>The Fix: Use Cloudflare Security Rules<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If your site is behind Cloudflare, <strong>IP-based access control must live at the Cloudflare layer<\/strong>, not in IIS.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cloudflare evaluates the visitor\u2019s <em>true<\/em> IP address before traffic ever reaches your server.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How to Do It<\/strong><\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>Log in to Cloudflare<\/li>\n\n\n\n<li>Go to <strong>Security \u2192 WAF \u2192 Custom Rules<\/strong><\/li>\n\n\n\n<li>Create a rule that:\n<ul class=\"wp-block-list\">\n<li><strong>Allows<\/strong> requests<\/li>\n\n\n\n<li>When IP Source Address <em>is in<\/em> your approved IP list<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>(Optional but recommended) Add a <strong>block-all rule<\/strong> below it<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">This ensures:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Only approved IPs reach your server<\/li>\n\n\n\n<li>IIS never sees unwanted traffic<\/li>\n\n\n\n<li>Your origin remains fully shielded<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Cloudflare\u2019s official documentation walks through this in detail:<br>\ud83d\udc49 <a href=\"https:\/\/developers.cloudflare.com\/waf\/tools\/ip-access-rules\/create\/\">https:\/\/developers.cloudflare.com\/waf\/tools\/ip-access-rules\/create\/<\/a><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Locking down access by IP address is a common and effective security practice. On Windows [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":625,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"categories":[18],"tags":[],"class_list":["post-622","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-coldfusion"],"_links":{"self":[{"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/posts\/622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/comments?post=622"}],"version-history":[{"count":1,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/posts\/622\/revisions"}],"predecessor-version":[{"id":626,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/posts\/622\/revisions\/626"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/media\/625"}],"wp:attachment":[{"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/media?parent=622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/categories?post=622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xbytecloud.com\/blog\/wp-json\/wp\/v2\/tags?post=622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}