Serial-over-LAN

VirtualBMC bridges IPMI SOL to the VM’s default libvirt console using virDomain.openConsole. This implementation targets ipmitool and Ironic’s ipmitool-socat console interface. SOL uses the same address, UDP port, username, and password as the virtual BMC’s power commands.

Prerequisites

  • A libvirt console supported by openConsole, normally a PTY serial console. If virsh console DOMAIN works, this is a suitable starting point. Disconnect virsh before activating SOL: VirtualBMC does not force another console client off the port.

  • Guest serial output/input configured appropriately, for example console=ttyS0,115200 and a serial getty for x86 Linux guests. Firmware serial redirection is needed to see firmware output.

  • A read-write libvirt connection with console access. The BMC’s existing libvirt URI and SASL credentials are used for the console connection.

Connecting

For a BMC listening on UDP port 6230:

ipmitool -I lanplus -C 3 -H 192.168.111.1 -p 6230 -U admin -a sol activate

-a prompts for the BMC password. Press Enter if the guest is idle. Exit with Enter followed by ~.. To release a stale SOL session from another terminal:

ipmitool -I lanplus -C 3 -H 192.168.111.1 -p 6230 -U admin -a sol deactivate

An external deactivation releases the console immediately. Some ipmitool versions ignore the unsolicited SOL-inactive notification; exit the old client locally if it remains open.

Set Ironic’s driver_info/ipmi_cipher_suite to 3 when using this pyghmi server, and select console_interface=ipmitool-socat. Ironic must also enable that console interface in its configuration. Its TCP console listener port is separate from the virtual BMC’s UDP port.

Scope and limitations

  • One client, SOL payload instance 1, and the default libvirt console per VM. Additional clients are rejected until the owner disconnects or is deactivated. Console selection and multiple readers are not implemented.

  • Activation while the VM is off is supported. The stream is attached when the VM starts and reattached after EOF or a libvirt disconnection, with a one-second retry interval. The earliest boot output can be missed during this interval; there is no history buffer or log replay.

  • Input typed while the console stream is absent is discarded. Input queued for an old stream is discarded on disconnection. Partial writes and nonblocking I/O are handled; a 4 KiB input queue bounds memory usage and an overflow closes SOL. Output is read one acknowledged packet at a time.

  • Client sessions expire after 60 seconds without client traffic. Normal ipmitool Get Device ID keepalives keep an idle session alive. Lost output acknowledgements also cause the console to be released.

  • sol info, sol set, per-user payload configuration, and serial BREAK are not implemented. The supported client is ipmitool with its default keepalive behavior.