I'm firewalling an Ubuntu Core 16.04 host: What port does snap package management require to be opened?

I spent ages Googling this: Snapcraft's docs don't detail the port nor did any other forums. Couldn't use tcpdump to derive the required port as snap find tcpdump gave no joy.

In the end, I had to packetsniff on the router. I'll provide the answer to hopefully save others firewalling Ubuntu Core hosts the same exercise in frustration...


In addition to allowing DNS of course, Ubuntu Core requires TCP/443 connectivity for snap package management to check for updates & install packages. The Ubuntu Core host on is using a port from the Dynamic/Private port range, TCP/35234

Packet Sniff Capture

Doing a host lookup of host reports the remote IP as Snapcraft's: domain name pointer api.snapcraft.io.

Anyhoo, hope this saves others some time-


I've been having the same issue and had to add the following domains to be able to establish http(s) connections:


At least, it was working after adding the fourth one.

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