This has been requested repeatedly, so let's give it a go. We explicitly do not allow matching
on names that have already been changed (from a previous udev run, or otherwise), and matching
on unpredictable names (ethX) is discouraged (but not currently disallowed).
We also currently allow:
[Match]
Name=veth0
[Link]
Name=my-name0
SomeOtherSetting=true
Which means that the link file will be applied the first time it is invoked, but
not on subsequent invocations, which may be surprising.
This does not belong in shared as it is mostly a detail of our networking subsystem.
Moreover, now we can use libudev here, which will simplify things.
According to Wikipedia it is customary to specify hardware metrics and
transfer speeds to the basis 1000 (SI decimal), while software metrics
and physical volatile memory (RAM) sizes to the basis 1024 (IEC binary).
So far we specified everything in IEC, let's fix that and be more
true to what's otherwise customary. Since we don't want to parse "Mi"
instead of "M" we document each time what the context used is.
This also changes the names to MTUBytes and BitsPerSecond, respectively. Notice
that the speed was mistakenly documented to be in bytes before this change.
Use Description only internally, and allow Alias to be set
as a separate option. For instance SNMP uses ifalias for
a specific purpose, so let's not write to it by default.
This introduces a new key MACAddressPolicy.
The possible policies are 'persistent' and 'random'.
'persistent' will do nothing if the current address is the hardware address,
but if the hardware does not have an address (or another address is set for
whatever reason), we will generate an address which will be random, but
persistent between boots (based on machineid and persistent netif name).
'random' will do nothing if the kernel already set a random address, otherwise
it will generate a random one and use that instead.
This patch sets MACAddressPolicy=persistent in the default .link file.
This introduces a new key NamePolicy, which takes an ordered list of naming
policies. The first successful one is applide. If all fail the value of Name
(if any) is used.
The possible policies are 'onboard', 'slot', 'path' and 'mac'.
This patch introduces a default link file, which replaces the equivalent udev
rule.
This tool applies hardware specific settings to network devices before they
are announced via libudev.
Settings that will probably eventually be supported are MTU, Speed,
DuplexMode, WakeOnLan, MACAddress, MACAddressPolicy (e.g., 'hardware',
'synthetic' or 'random'), Name and NamePolicy (replacing our current
interface naming logic). This patch only introduces support for
Description, as a proof of concept.
Some of these settings may later be overriden by a network management
daemon/script. However, these tools should always listen and wait on libudev
before touching a device (listening on netlink is not enough). This is no
different from how things used to be, as we always supported changing the
network interface name from udev rules, which does not work if someone
has already started using it.
The tool is configured by .link files in /etc/net/links/ (with the usual
overriding logic in /run and /lib). The first (in lexicographical order)
matching .link file is applied to a given device, and all others are ignored.
The .link files contain a [Match] section with (currently) the keys
MACAddress, Driver, Type (see DEVTYPE in udevadm info) and Path (this
matches on the stable device path as exposed as ID_PATH, and not the
unstable DEVPATH). A .link file matches a given device if all of the
specified keys do. Currently the keys are treated as plain strings,
but some limited globbing may later be added to the keys where it
makes sense.
Example:
/etc/net/links/50-wireless.link
[Match]
MACAddress=98:f2:e4:42:c6:92
Path=pci-0000:02:00.0-bcma-0
Type=wlan
[Link]
Description=The wireless link
