Blocking outbound ports on GX20

[Evan8571]

An organization I'm with has recently had an issue with one of the computers getting corrupted and sending outbound port 23 traffic DDoS.  We're looking to put in a meraki go system anyway and wondering if we can block outbound port 23 or if it would be best to put a specific firewall device such as a netgate with pfsense or something.  I have recently installed a meraki go with another fire station and seems to be working well and I'm getting familiar with it and trying to read through all the documentation I can, but have not seen how I could do this without purchasing the security subscription (which I'm still trying to figure out how to purchase and whether I need it).

[Satsuki]

Not sure if you got your answer yet or not, but I do not believe there is a way to make firewall rules on the Meraki Go devices. 

As far as the security subscription, that has a few more features for things like content filtering but not for configuring the firewall in the manner requested.