Find MAC addresses in /proc or somewhere despite bonding device?

Question

Is there a way to get the original MAC addresses for eth0 and eth1?

A large array of servers have bonding interfaces managing backup switch connections and one is misbehaving. With bond0 active both MAC addresses are replaced and reported identically by ifconfig.

I want to search the server array for a MAC address I found in a Cisco device.

I would use dmesg(1) or /var/log/messages, but they have been rolled over for hundreds of days for most of the array.

Answer 1

try the /sys filesystem:

$ cat /sys/class/net/eth?/address
00:25:90:31:f6:f4
00:25:90:31:f6:f5

Answer 2

The OS should keep a list of physical NIC details within the file:

/etc/udev/rules.d/70-persistent-net.rules

Here is mine as an example:

# This file maintains persistent names for network interfaces.
# See udev(7) for syntax.
#
# Entries are automatically added by the 75-persistent-net-generator.rules
# file; however you are also free to add your own entries.

# PCI device 0x10ec:0x8168 (r8169)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:23:54:95:74:e5", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

Notice the "ATTR{address}==" section?

Answer 3

I'm still searching for a more "official" explanation, but according to this blog, the file /proc/net/bonding/${bonding name} will provide the actual mac address for each NIC in the bond (eth0, eth1, etc..), so that might be more useful.

Hope this will help!

Answer 4

You can use arp to find a MAC address

To find the manufactors MAC the IEEE Registration Authority keeps a list of brand names that belong and there MAC addresses, the first six in a MAC address are the brand name followed by type and serialnumber

Search the Public OUI/'company_id' Listing