# Firewall - [Main page](https://cloud.google.com/) # Tech thinks to remember - by default there are firewall rules to allow access on rdp, ssh, IMCP, and internal communication. - firewall rules can use ip addresses, or network tags, or service accounts. - access to the metadata server (`169.254.169.254`) is always allowed. - Access to external servers on port 25 (SMTP) is blocked.