Home / server / Questions / 357811
Accepted
DigitalRoss
Asked: 2012-02-08 14:57:02 +0800 CST

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

  • 772

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.

linux centos redhat

8 Answers

  1. Best Answer

    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!

    • 9

  2. On RHEL/CentOS 6:

    # ethtool -P <if>

Permanent address: 00:11:22:33:44:55
    • 8

  3. You can get this from /sys instead of /proc. For example:

    $ cat /sys/class/net/eth0/address
0a:58:ac:16:05:13

    All the interfaces available are listed under net:

    $ ls /sys/class/net/
eth0  lo
    • 7

  4. 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?

    • 3

  5. There's a few ways both for SATA and NET devices. Commands like udevadm info will do it as well. ifconfig and netstat as well. And the list goes on. Check some of the old links for above for the full set.

    • 0

  6. 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

    • -2

  7. dmesg | grep eth0 && dmesg | grep eth1

    You can grab the reported hardware addresses for any interface prior to the bond being established.

    • -3

  8. If you are not sure of the interface name (happens with CentOS 7) try: ip addr

    and just pick the interface from the list

    • -3