Nebulizer: Certificate Generation at Scale for Slack Nebula Overlay Network Made Easy

Nebula Network

Slack Nebula is an overlay network. Basically an on-demand VPN mesh system, Nebula allows hosts in different networks and locations to auto-create encrypted communication channels between each other. A virtual interface is provided to the operating system, and a unique IP address. Once communication has been established, the nodes see each other as being on the same LAN.

Reflashing a Chinese Seriallink SLK-e940 4G LTE Gateway Router with OpenWRT

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Recently, I needed an LTE backup at a secondary home location with an unreliable primary internet connection. I was somewhat bewildered by the plethora of options available. I saw a weatherized Seriallink SLK-e940 on eBay for a very nice price, so I looked up the details on it. I found (from the help screenshots) that it appeared to run a modified version of OpenWRT. The image the seller provided showed inside the unit a mini-PCIe Quectel EC25-AF LTE modem, which I knew had good Linux support.