diff --git a/src/Composer/Util/Http/CurlDownloader.php b/src/Composer/Util/Http/CurlDownloader.php
index f5bbe24aa..e512f0824 100644
--- a/src/Composer/Util/Http/CurlDownloader.php
+++ b/src/Composer/Util/Http/CurlDownloader.php
@@ -23,13 +23,14 @@ use Composer\Util\AuthHelper;
 use Composer\Util\Url;
 use Composer\Util\HttpDownloader;
 use React\Promise\Promise;
+use Symfony\Component\HttpFoundation\IpUtils;
 
 /**
  * @internal
  * @author Jordi Boggiano <j.boggiano@seld.be>
  * @author Nicolas Grekas <p@tchwork.com>
  * @phpstan-type Attributes array{retryAuthFailure: bool, redirects: int<0, max>, retries: int<0, max>, storeAuth: 'prompt'|bool, ipResolve: 4|6|null}
- * @phpstan-type Job array{url: non-empty-string, origin: string, attributes: Attributes, options: mixed[], progress: mixed[], curlHandle: \CurlHandle, filename: string|null, headerHandle: resource, bodyHandle: resource, resolve: callable, reject: callable}
+ * @phpstan-type Job array{url: non-empty-string, origin: string, attributes: Attributes, options: mixed[], progress: mixed[], curlHandle: \CurlHandle, filename: string|null, headerHandle: resource, bodyHandle: resource, resolve: callable, reject: callable, primaryIp: string}
  */
 class CurlDownloader
 {
@@ -279,6 +280,7 @@ class CurlDownloader
             'bodyHandle' => $bodyHandle,
             'resolve' => $resolve,
             'reject' => $reject,
+            'primaryIp' => '',
         ];
 
         $usingProxy = $proxy->getFormattedUrl(' using proxy (%s)');
@@ -505,6 +507,18 @@ class CurlDownloader
                     }
                 }
 
+                if (isset($progress['primary_ip']) && $progress['primary_ip'] !== $this->jobs[$i]['primaryIp']) {
+                    if (
+                        isset($this->jobs[$i]['options']['prevent_ip_access_callable']) &&
+                        is_callable($this->jobs[$i]['options']['prevent_ip_access_callable']) &&
+                        $this->jobs[$i]['options']['prevent_ip_access_callable']($progress['primary_ip'])
+                    ) {
+                        throw new TransportException(sprintf('IP "%s" is blocked for "%s".', $progress['primary_ip'], $progress['url']));
+                    }
+
+                    $this->jobs[$i]['primaryIp'] = (string) $progress['primary_ip'];
+                }
+
                 // TODO progress
             }
         }
diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index 0cc9df772..6fa3437a3 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -249,6 +249,10 @@ class RemoteFilesystem
 
         $origFileUrl = $fileUrl;
 
+        if (isset($options['prevent_ip_access_callable'])) {
+            throw new \RuntimeException("RemoteFilesystem doesn't support the 'prevent_ip_access_callable' config.");
+        }
+
         if (isset($options['gitlab-token'])) {
             $fileUrl .= (false === strpos($fileUrl, '?') ? '?' : '&') . 'access_token='.$options['gitlab-token'];
             unset($options['gitlab-token']);