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I have Many server booted up to Debian 12 connected to a common switch. All I know is their BMC Macs and bmc passwords for each unit(all of them not from same manufacturer).

Is there a standard way to find out all Eth Interfaces IP address of the corresponding BMC Mac (Unit)? Is the any Ipmitool command to get IP Addresses of all the NICs?

Hint:

  1. I Only have IP address of one of those units and I can ssh into it(This is my DHCP server).
  2. On the machine mentioned above, I can run arp-scan and get all the ip addresses of those other machines which are connected to the same switch but how do I tell which ip belongs to what corresponding BMC Mac address.
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1 Answer 1

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There is a number of possible solutions for your problem.

  • You could read the configuration file and the lease file of the DHCP server, and find out the IP <-> MAC address associations from there.

For example, with an ISC DHCP server, you'd find any permanently-via-DHCP assigned IP addresses in the DHCP configuration file /etc/dhcp/dhcpd.conf:

host bmcname {
        hardware ethernet 12:34:56:78:90:ab;
        fixed-address 192.168.12.34;
        ...

And any non-permanent assignments in the DHCP lease file /var/lib/dhcp/dhcpd.leases:

lease 192.168.12.48 {
  starts 5 2024/09/27 05:22:47;
  ends 5 2024/09/27 13:22:47;
  cltt 5 2024/09/27 05:22:47;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 23:45:67:89:0a:bc;
  ...
  • After running arp-scan, you could ping an IP address (or do anything else that causes traffic sent to it) from any system in the same network segment, then if the target IP address responds to ping, immediately afterwards run arp -a to view the local ARP table.
$ ping -c 1 192.168.12.34 >/dev/null   # just to create some traffic
$ /sbin/arp -a | grep 192.168.12.34
bmc.server.name (192.168.12.34) at 12:34:56:78:90:ab [ether] on eno1
  • You could install the ipmiutil package, run ipmiutil discover and get a list of all IP addresses responding to IPMI requests (i.e. the BMC interfaces) together with their BMC-configured hostnames.

Example with just one BMC:

$ ipmiutil discover
idiscover ver 1.11
Discovering IPMI Devices:
01| response from |  192.168.12.34      | bmc.server.name 

idiscover: 1 pings sent, 1 responses
ipmiutil discover, completed successfully
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  • My bad if the question is not clear. I want to know the network IP Address ( the one on the NIC ... eth0 eth1 eth2 etc) of those machines not the bmc ip. Commented Oct 3, 2024 at 19:39
  • I found a work around which works but is inefficient. I SSH into every IP returned my arp-scan with a timeout of 15 seconds. once SSH is successful into the right machine dump the IP table and BMC IP to the main server. this solutions is a hit and trial method and wastes a lot of time by trying to SSH into machines that are not targeted. Commented Oct 3, 2024 at 19:45

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