keelRM: a BMC for machines without one
What you get
Open https://host-address:8623/ and log in with the keelOS administrator password:
- Status: whether the host runs, how long it has been restarting, the crash reason, the active slot.
- The host's screen, a serial console you can type in (loader, kernel messages, login), and the log of the hypervisor.
- Buttons: reload the host, reset, power off, restart keelRM, boot another slot once.
- Rescue: put the management address back, reset the administrator password, start in safe mode (no autostart, no passthrough devices).
- TLS only, limited to the management network by default, rate-limited logins, every action in the audit log.
How it works
The hypervisor starts a small Linux VM (1 CPU, 64 MiB, no disk) before the host. The management NIC belongs to it, not to the host. While the host runs, the VM only forwards traffic and keeps port 8623 for itself; when the host is gone, it answers ARP, ping and 8623 with the host's address.
What was measured
- Three host reloads with pings every 200 ms: 816 pings, none lost, three VMs suspended and resumed.
- Throughput through keelRM on a 1G port: 842 / 938 Mbit/s against 941 / 941 direct.
- Rescue tested: a wrong address, a password reset and safe mode were all repaired from the page. Restarting keelRM itself takes 2.5 s.
Limits
- Intel VT-d is needed. AMD is not supported yet.
- Tested on one multi-port Supermicro server. Boxes with a single network port should work, because all their traffic then goes through keelRM, but are not tested.
- It cannot power a switched-off machine on (use Wake-on-LAN), the screen is view-only (type on the serial console), and there is no virtual CD drive.
- If the hypervisor itself dies, keelRM goes with it.