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I'd like to install Ethernet in my Ubuntu, but the error message still be occurred like this:

tcpdump: eth0: No such device exists
(SIOCGIFHWADDR: No such device)



root@ubuntu:~# tcpdump -D
1.ens33 [Up, Running]
2.any (Pseudo-device that captures on all interfaces) [Up, Running]
3.lo [Up, Running, Loopback]
4.bluetooth0 (Bluetooth adapter number 0)
5.nflog (Linux netfilter log (NFLOG) interface)
6.nfqueue (Linux netfilter queue (NFQUEUE) interface)
7.usbmon1 (USB bus number 1)
8.usbmon2 (USB bus number 2)

I have only these things in my Ubuntu.

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1 Answer 1

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ens33 is your Ethernet interface. It just isn't called "eth0" like the good old days. I'm not sure what the algorithm is for naming interfaces, but they end up being unique.

edit:

See man systemd.link.

The fact that your prefix is "ens" indicates that your naming convention is "slot". Reference that section in https://www.freedesktop.org/software/systemd/man/systemd.net-naming-scheme.html

(Search the page for "ID_NET_NAME_SLOT").

Reading this article will also explain other device name prefixes besides "ens" you may find. For example, mine is "enp" which means it was named with the "ID_NET_NAME_PATH" method.

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  • That article says it is obsolete by this man file: freedesktop.org/software/systemd/man/… the method that udev uses to name the interfaces is specified in a udev rules file. I'm not in front of an ubuntu box at the moment, but on another distribution, I'm seeing it at /usr/lib/udev/rules.d/80-net-name-slot.rules. use locate and grep to find it. E.g. type locate rules.d | grep net
    – Rich
    Feb 10, 2020 at 19:35
  • NNnnnopee, that's not on an 18.04 system. Also, the manpage actually points at systemd.io/PREDICTABLE_INTERFACE_NAMES which is more easy to understand. BUT says basically the same general thing that unpredictible naming (eth0, etc.) are replaced by predictable naming and explains things better. (And points to the manpage for the naming layouts)
    – Thomas Ward ♦
    Feb 10, 2020 at 19:37
  • Lol. That link points to the same resource I provided a link to. freedesktop.org/software/systemd/man/… to explain how the naming is done.
    – Rich
    Feb 10, 2020 at 19:42

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