Re: [gentoo-user] Re: Ethernet Machination

[Kerin Millar <kerframil@fastmail.co.uk>]

james wrote:
> After deleting the 70-persistent-net.rule file
>
> udev does not re-create it. All is now fine with rc-status
> only showing net.eth0 which is set up how I like it
> per /etc/conf.d/net. All services are fine

Beware. The automatic persistent net rules generator is intrinsically 
broken because naming eth* devices within the same namespace (eth* to 
eth*) can break things horribly. I have had this happen to me on several 
occasions and was helping someone out in #gentoo who had experienced the 
same issue only recently.

For more information, take a look at this bug:

   https://bugzilla.redhat.com/show_bug.cgi?id=782145

Because of this, Kay Sievers has removed the rule generator from later 
versions of udev (*). The current version of udev marked stable in 
gentoo still has it but it can be disabled by setting 
USE="-rule_generator". I've started doing exactly that on my systems 
because it has only ever caused problems instead of providing solutions. 
Besides which, eventually a version of udev will be stabilized that no 
longer has it.

If you want to use persistent net rules, the only safe way of doing it 
is to define the rules manually and to rename interfaces in such a 
fashion that they don't conflict with the existing device namespace. For 
example, you could rename "eth0" to "lan", "eth1" to "dmz" or whatever 
is deemed appropriate.

This doesn't appear to be common knowledge, so it struck me as worth 
mentioning.

Cheers,

--Kerin

* I cannot recall the exact version off-hand.