CentOS 6/7

[Brian Cluff]

Here's the description of the naming convention that is used, taken from 
the kernel source:

  Two character prefixes based on the type of interface:
    en — Ethernet
    ib — InfiniBand
    sl — serial line IP (slip)
    wl — wlan
    ww — wwan

Type of names:
b<number>
             — BCMA bus core number
c<bus_id>
             — bus id of a grouped CCW or CCW device, with all leading 
zeros stripped [s390]
o<index>[n<phys_port_name>|d<dev_port>]
             — on-board device index number
s<slot>[f<function>][n<phys_port_name>|d<dev_port>]
             — hotplug slot index number
x<MAC>
             — MAC address
[P<domain>]p<bus>s<slot>[f<function>][n<phys_port_name>|d<dev_port>]
             — PCI geographical location
[P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]
             — USB port number chain
v<slot>
             — VIO slot number (IBM PowerVM)
a<vendor><model>i<instance>
             — Platform bus ACPI instance id

All multi-function PCI devices will carry the [f<function>] number in the
  device name, including the function 0 device.

  SR-IOV virtual devices are named based on the name of the parent 
interface,
  with a suffix of "v<N>", where <N> is the virtual device number.

When using PCI geography, The PCI domain is only prepended when it is not 0.

For USB devices the full chain of port numbers of hubs is composed. If the
  name gets longer than the maximum number of 15 characters, the name is not
  exported.
  The usual USB configuration == 1 and interface == 0 values are suppressed.

  PCI Ethernet card with firmware index "1":
    ID_NET_NAME_ONBOARD=eno1
    ID_NET_NAME_ONBOARD_LABEL=Ethernet Port 1

  PCI Ethernet card in hotplug slot with firmware index number:
    /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1
    ID_NET_NAME_MAC=enx000000000466
    ID_NET_NAME_PATH=enp5s0
    ID_NET_NAME_SLOT=ens1

  PCI Ethernet multi-function card with 2 ports:
    /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0
    ID_NET_NAME_MAC=enx78e7d1ea46da
    ID_NET_NAME_PATH=enp2s0f0
    /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1
    ID_NET_NAME_MAC=enx78e7d1ea46dc
    ID_NET_NAME_PATH=enp2s0f1

  PCI wlan card:
    /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0
    ID_NET_NAME_MAC=wlx0024d7e31130
    ID_NET_NAME_PATH=wlp3s0

  PCI IB host adapter with 2 ports:
    /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.0/net/ibp21s0f0
    ID_NET_NAME_PATH=ibp21s0f0
    /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.1/net/ibp21s0f1
    ID_NET_NAME_PATH=ibp21s0f1

  USB built-in 3G modem:
/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6
    ID_NET_NAME_MAC=wwx028037ec0200
    ID_NET_NAME_PATH=wwp0s29u1u4i6

  USB Android phone:
/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2
    ID_NET_NAME_MAC=enxd626b3450fb5
    ID_NET_NAME_PATH=enp0s29u1u2

  s390 grouped CCW interface:
   /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0
   ID_NET_NAME_MAC=enx026d3c00000a
   ID_NET_NAME_PATH=encf5f0

Brian Cluff

On 12/4/18 1:41 PM, Brian Cluff wrote:
> On 12/4/18 12:40 PM, Snyder, Alexander J wrote:
>> Does anyone know why networking devices aren't eth0/1/2/3 but are now 
>> ens0f0/enp0d0.
>
> Those are the new "Predictable Network Interface Names" based on where 
> they are physically plugged into the system.
> You can read all about them here:
> https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/ 
>
> In a nut shell they make sure that you device names don't ever change 
> which is really annoying when you have a server is hosted out of state 
> and can't get your hands on it to fix all your scripts that use eth0 
> as your internet facing interface when it suddenly switches places 
> with eth1 or gets bumped to eth3 for any number of reasons.
> The new names are a little jarring at first, but if you allow yourself 
> to get used to them then you will be able to tell someone, without any 
> doubt, based on the devices name which exact device needs to be 
> swapped out when it fails, and the replacement device will be given 
> the same name, as long as it's plugged into the same place)
>
>> Also getting into single user mode now is (IMHO) unnecessarily 
>> complicated (typing 'single' versus now 'init=/sysroot/bin/bash').
>
> init=/sysroot/bin/bash has always worked and is my preferred way of 
> getting into a system without running anything else.  That line simply 
> tells grub to bypass starting the system's init system which is 
> systemd on the newer systems and to instead run bash as linux's init.
>
> If you are looking to get into a true single user mode you will 
> probably want to instead use one of the following lines where you were 
> previously using init=/sysroot/bin/bash:
>
> systemd.unit=rescue.target (can be shortened to systemd.unit=rescue)
> or
> systemd.unit=emergency.target (can be shortened to 
> systemd.unit=emergency)
>
> The emergency target is the most minimal of the 2.
>
> Brian Cluff
>
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