[systemd-devel] container virtual Ethernet link naming

[Johannes Ernst]

> On Oct 9, 2015, at 13:00, Dan Williams <dcbw at redhat.com> wrote:
> 
> On Fri, 2015-10-09 at 12:53 -0700, Johannes Ernst wrote:
>> man systemd-nspawn, section on --network-veth
>>    "The container side of the Ethernet link will be named <literal>host0</literal>."
>> 
>> container> ip link
>> ...
>> 2: host0 at if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
>>    link/ether ce:d3:4f:6c:44:5f brd ff:ff:ff:ff:ff:ff link-netnsid 0
>> 
>> Where does the @if9 come from, and what’s the naming scheme here?
> 
> It comes from /sbin/ip.  What's after the @ is the interface index of
> the veth peer, so "if9" == interface index 9 and that tells you what the
> peer link will be outside the container/namespace.  The stuff after the
> @ isn't controlled by systemd/udev, the "if" prefix is hardcoded
> in /sbin/ip.

This is actually cool, and as far as I can find, entirely undocumented :-)

I put a paragraph on the Arch wiki: https://wiki.archlinux.org/index.php/Systemd-nspawn#Virtual_Ethernet_interfaces based on your information. Thank you!

Cheers,



Johannes.