IC-OS is the operating system that runs on Internet Computer nodes. It's based on Ubuntu Linux and customized specifically for the IC.
IC-OS is actually three different operating systems that work together, each with a specific job.
SetupOS
SetupOS is used when setting up a new node for the first time. Node providers download the SetupOS onto a USB drive, plug it into their node machine and boot from it. The SetupOS automatically sets everything up and then the machine reboots into the HostOS.
What it does:
- Checks that the hardware meets requirements
- Tests network connectivity
- Installs the other two operating systems (HostOS and GuestOS)
- Sets up the node with necessary settings and security keys
HostOS
HostOS runs directly on the physical hardware. Its job is to configure and run the Guest virtual machine.
What it does:
- Runs a virtual machine that contains GuestOS
- Manages hardware resources
- Handles system upgrades
- Provides a security barrier between hardware and the ICP software
GuestOS
GuestOS runs inside a virtual machine on the HostOS. This is where the actual Internet Computer software runs.
What it does:
- Runs the replica
- Runs canisters and manages their state
- Participates in consensus with other nodes
- Manages cryptographic keys and operations
Running GuestOS in a virtual machine ensures every node has the exact same environment, regardless of the underlying hardware. Furthermore, running GuestOS in a virtual machine allows better separation from a potentially malicious host.