diff --git a/security/firewall.md b/security/firewall.md
index 23c925cc..dfd5351b 100644
--- a/security/firewall.md
+++ b/security/firewall.md
@@ -22,7 +22,7 @@ the user is free to create more, if needed.
 For more information, see the following:
 
 -   [https://groups.google.com/group/qubes-devel/browse\_thread/thread/9e231b0e14bf9d62](https://groups.google.com/group/qubes-devel/browse_thread/thread/9e231b0e14bf9d62)
--   [http://theinvisiblethings.blogspot.com/2011/09/playing-with-qubes-networking-for-fun.html](http://theinvisiblethings.blogspot.com/2011/09/playing-with-qubes-networking-for-fun.html)
+-   [https://blog.invisiblethings.org/2011/09/28/playing-with-qubes-networking-for-fun.html](https://blog.invisiblethings.org/2011/09/28/playing-with-qubes-networking-for-fun.html)
 
 How to edit rules
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