diff --git a/openvpn-server/readme.md b/openvpn-server/readme.md
index c9f244c..a331d14 100644
--- a/openvpn-server/readme.md
+++ b/openvpn-server/readme.md
@@ -1,4 +1,6 @@
 Start the IPsec VPN server
 VERY IMPORTANT ! First, run this command on the Docker host to load the IPsec NETKEY kernel module:
 
-sudo modprobe af_key
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+sudo modprobe af_key
+
+https://github.com/hwdsl2/docker-ipsec-vpn-server
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