diff --git a/_config.yml b/_config.yml
index 6d19738..73784da 100644
--- a/_config.yml
+++ b/_config.yml
@@ -49,6 +49,11 @@ aux_links:
 # Makes Aux links open in a new tab. Default is false
 aux_links_new_tab: true
 
+# External navigation links
+nav_external_links:
+  - title: MPTCP sysctl
+    url: https://docs.kernel.org/networking/mptcp-sysctl.html
+
 callouts:
   warning:
     title: Warning