Difference between revisions of "Troubleshooting/BMC Connection Guide"
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Revision as of 19:24, 4 September 2022
Contents
BMC Connection Guide
This document will guide you through the process of connecting your system BMC to an external network and gaining access to the root command line shell therein. It is assumed you will have access to a Linux based computer during this process, and that you have not set your BMC to use a static IP address. If you have already set your BMC to use a static IP address, please use a Linux computer that has access to that IP and skip to the SSH section. Note that you cannot access the BMC in any way from the host system over network -- the NCSI interface has no support for this, and all access including pings will fail.
Overview
The BMC exposes a network interface on a specific network port for each product as listed:
- Talos II: The left-most network port, nearest the serial port on the rear panel of the mainboard
- Blackbird: The left-most network port, on top of the USB ports, nearest the serial port on the rear panel of the mainboard
When the system is attached to AC power after being disconnected, the stock BMC firmware goes through a startup process that involves acquiring a DHCP address from any DHCP server available on the network attached to the BMC network interface. The goal of this section of the guide is to allow the BMC to acquire an address so that a root shell may be obtained for diagnostic purposes.
Configure a DHCP server
If a DHCP server is already present on the network the BMC is attached to, please skip this step.
There are several different methods to set up a Linux machine as a DHCP server. While there are a variety of online guides for this task, we have summarized a few popular distro methods below:
Once the server is online, continue to the next step.
Allow the BMC to acquire a network address
Connect the network with the DHCP server to the BMC network interface on the mainboard. If the system is plugged into AC power, unplug it and wait for all LEDs to extinguish on the mainboard. Plug the system in and wait for the BMC startup process to start (front panel lights to stop flashing).
Determine the BMC network address
While several different methods exist to determine the IP address handed out by your DHCP server, one of the fastest for small local networks is a simple nmap scan. Please consult your organization security policy if the network is not under your direct control -- some organizations consider even a ping scan like this one to be a security incident. If your organization objects to a scan and cannot provide you with the leased IP for the BMC, we recommend setting up a local test network between your Linux machine and the BMC which you can safely scan at will.
nmap -sn <your IP prefix>/<your CIDR range>
For example, nmap -sn 192.168.0.0/16
Discount the IP address of your local host -- on a two-device local network, the other IP address will be the address the BMC has acquired.
SSH to the BMC
Using the IP address of the BMC, SSH as follows:
ssh root@<IP address of BMC>
If you haven't changed the password yourself, it will be the factory password. Once this step is completed, you should receive a root shell on the BMC.
