CentOS - Jun 2018 - Semi-OT: ipmitool or ipmicfg: set BMC to use NIC 2

Date: Wed, 27 Jun 2018 20:45:44 -0400
From: Jonathan Billings <billings at negate.org>
> On Wed, Jun 27, 2018 at 05:14:06PM -0400, mark wrote:
>
>> I do see one option of "defgw macaddr" - is that supposed to
be a MAC
>> external to the server, or can I use the MAC of eth1 (or whatever the
>> stupid, unrememberable name is)?
>
> As mentioned earlier, the BMC is a different MAC from any interface
> you might see from the OS side.  Think of it as a separate computer that
> shares a physical network port (assuming it doesnt have a dedicated port).
> Imagine what would happen if you put two devices on the network with
> the same MAC.  You don't want to do that.  defgw macaddr is for setting
> what it thnks the Default Gateway's MAC address is.
>
> You will need to set the IP, netmask and gateway using the appropriate
> tool (I prefer ipmitool).  keep in mind that because the device shares a
> port you most likely wont be able to use IPMI to talk over the LAN to the
> device from the OS on the same box.
It's the end of the week, and maybe I'm being dense, but I still
don't get
it: how do I tell the BMC to use eth1? Do I give it eth1's MAC address as
a gateway?

         mark

On Fri, Jun 29, 2018 at 05:30:26PM -0400, mark wrote:
> It's the end of the week, and maybe I'm being dense, but I still
don't get
> it: how do I tell the BMC to use eth1? Do I give it eth1's MAC address
as
> a gateway?
No, use the IP and MAC of the gateway you wish it to use, as if you
were configuring another network device that's on the same network as
eth1 (assuming it's sharing the eth1 physical network port).  THe
important thing to remember is: The BMC is not eth1.  It just happens
to share the physical port you're plugging an ethernet cable into.  It
behaves like there's another computer inside your case, with a vampire
tap on the ethernet port's cable.

For example, if this is your eth1:

$ ip -4 a show dev eth1
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
state UP group default qlen 1000
    inet 10.0.0.5/24 brd 10.0.0.255 scope global dynamic
    noprefixroute eth1
           valid_lft 567262sec preferred_lft 567262sec
$ ip -4 route
default via 10.0.0.1 dev eth1 proto dhcp metric 100
10.0.0.0/24 dev eth1 proto kernel scope link src 10.0.0.5 metric 100
$ arp -n 10.0.0.1
Address                  HWtype  HWaddress           Flags Mask Iface
10.0.0.1                 ether   00:00:11:11:22:22   C          eth1


Then you would pick an IP on your network (lets call it 10.0.0.6) and
set the IPMI interface to use 10.0.0.6/255.255.255.0 and use 10.0.0.1
and 00:00:11:11:22:22 as the defgw MAC.

You won't be able to ping the IP from the same system, but it should
be reachable from other systems on the 10.0.0.0/24 network above.

-- 
Jonathan Billings <billings at negate.org>

Once upon a time, mark <m.roth at 5-cent.us> said:
> It's the end of the week, and maybe I'm being dense, but I still
don't get
> it: how do I tell the BMC to use eth1? Do I give it eth1's MAC address
as
> a gateway?
Choosing the NIC(s) for IPMI is not a general configuration of IPMI;
that's going to be a vendor/hardware specific setting (if it can be done
at all).  Different vendors have different methods of configuring which
NIC(s) have IPMI access.  You won't be able to configure that with
ipmitool; it'll typically have to be set in the BIOS and/or BMC boot
configuration menus.

-- 
Chris Adams <linux at cmadams.net>