diff --git a/OCI;-Oracle-Cloud-Instance;-Quick-how-to-enable-DynMap.md b/OCI;-Oracle-Cloud-Instance;-Quick-how-to-enable-DynMap.md
index c6c15c3..2370756 100644
--- a/OCI;-Oracle-Cloud-Instance;-Quick-how-to-enable-DynMap.md
+++ b/OCI;-Oracle-Cloud-Instance;-Quick-how-to-enable-DynMap.md
@@ -67,6 +67,13 @@ sudo ufw allow 25565/tcp
 sudo ufw allow 19132/udp
 ```
 
+N.B : For the first command, you can see I didn't specify the port, but the service name, so the first command "sudo ufw allow ssh" is equal to "sudo ufw allow 22/tcp".
+In fact, you can use any service name, which you can retrieve this way : 
+```
+cat /etc/services
+```
+
+
 Add any rules you needs, then once done, we enable the firewall with those new rules (and check that everything is OK with the status command) : 
 
 ```