diff --git a/Linux_reinstall/Ubuntu/CloudInit/ipv4_static_interfaces.cfg b/Linux_reinstall/Ubuntu/CloudInit/ipv4_static_interfaces.cfg
index 0cdf2fe..92a0834 100644
--- a/Linux_reinstall/Ubuntu/CloudInit/ipv4_static_interfaces.cfg
+++ b/Linux_reinstall/Ubuntu/CloudInit/ipv4_static_interfaces.cfg
@@ -65,6 +65,7 @@ network:
 # Reload systemd.
 # Make sshd service loading automatically at the next reboot.
 # Kill the original sshd service so that to liberate the occupation of "0.0.0.0:22" and "[::]:22" to avoid "error: Bind to port sth on sth failed: Address already in use." causes restarting and applying new configs failure of the sshd service.
+# Allow sshd port for ufw.
 # Disable kernel need to restart: https://askubuntu.com/questions/1349884/how-to-disable-pending-kernel-upgrade-message
 # Install some common components.
 # Configure vim for more convenient to use.