SSH Tunnelling

At school port 3389 is blocked, so you can not RDP out.
One solution is to create a new EC2 instance and open up port 22 & 3389 and use it for local port forwarding

ssh -i "your_certificate.pem" -L IP_of_local_host:3389:IP_Address_of_RDP_Machine:3389 ubuntu@IP_Address_of_SSH_Tunnel

xfreerdp /v:IP_of_local_host:3389 /u:Administrator /f