diff --git a/README.md b/README.md
index 5e1c6da..1c7f410 100644
--- a/README.md
+++ b/README.md
@@ -2,8 +2,11 @@
 
 ## How to install
 
+SSH into your OPNsense:
 ```
 fetch -o /usr/local/etc/rc.syshook.d/start/99-checkmk_agent https://github.com/bashclub/check-opnsense/raw/main/opnsense_checkmk_agent.py
 chmod +x /usr/local/etc/rc.syshook.d/start/99-checkmk_agent
 /usr/local/etc/rc.syshook.d/start/99-checkmk_agent
 ```
+
+Ensure you create a packet filter rule to allow connections from your checkmk server to the firewall on port 6556.