supermicro IPMI web interface through shared LAN is blocking the operating system

Question

I recently hosted a supermicro 4029 server in an IDC facility. The IDC provides a static IP, subnet mask and DNS. After setting up the internet in CentOS without problem, I then proceed with setting up the IPMI which helps me with remote maintenance. The IPMI is configured with the same IP, subnet mask and DNS. It is configured to use the shared LAN1 and set up the MAC address to LAN1. Upon setting up, I am able to connect to the IPMI web interface with the static IP, but lost connect with the SSH connection to the OS. I then had to logon the KVM through IPMI web interface, use the IPMICFG tool to set the MAC address to anything other than LAN1's MAC. After that, I gained access to the server via SSH, but lost connection to the IPMI web interface.

It seems that as long as the IPMI mac address is set to LAN1, it blocks the OS and the SSH becomes accessible, but the mac address must be set to LAN1 if I want to access IPMI web interface. I have three ports on the motherboard, the dedicated IPMI port, LAN1 and LAN2. Setting the MAC address to anything other than LAN1 is useless.

Has anyone seen this before? Help appreciated and thanks in advance.

Answer 1

The shared interface port on the server for IPMI remote management has a Different MAC internally than the OS accessible port. You need to use a different IP to reach it.

Using the same IP gives you all of the same issues of having two devices with the same IP on the network.

If you have another system on the remote network, you can recover by creating a custom ARP entry on that host for the IPMI MAC with a temporary IP, and logging into that new IP and changing the IPMI IP within the Webgui.

If you have the Supermicro IPMI tools installed on the affected host, you can use the same trick to log into the host and reset the IPMI IP address via that method as well.

Otherwise the host will have to be shut down locally and someone change the IPMI interface IP within the BIOS.

I would strongly suggest that you make the IPMI interface address only accessible to a different subnet or vLAN since there are Security issues with all versions of IPMI.