From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: Bug handling devices with weird names
Date: Thu, 8 Jul 2010 10:27:47 -0700
Message-ID: <20100708102747.66d0ad78@s6510>
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Cc: netdev <netdev@vger.kernel.org>,
	Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
To: =?ISO-8859-1?B?TWFydO1u?= Ferrari <martin.ferrari@gmail.com>
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On Thu, 8 Jul 2010 19:08:07 +0200
Mart=EDn Ferrari <martin.ferrari@gmail.com> wrote:

> According to dev_valid_name (net/core/dev.c), a valid device name is
> one that doesn't include spaces, slashes, and is not "." or "..". But
> if I create a device called "foo:", some operations fail:
>=20
> # ip link add name foo: type dummy
> # ip link list foo:
> 155: foo:: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN ioctl(SIO=
CGIFXQLEN)
> failed: No such device
>=20
>     link/ether 92:7f:4d:0d:8f:57 brd ff:ff:ff:ff:ff:ff
>=20
> Strace reveals that the problem occurs when executing an ioctl:
>=20
> ioctl(4, SIOCGIFTXQLEN, {ifr_name=3D"foo:", ???}) =3D -1 ENODEV (No s=
uch device)
>=20
> ifconfig gets completely lost, of course:
>=20
> $ /sbin/ifconfig foo:
> foo:: error fetching interface information: Device not found
>=20
> ioctl(5, SIOCGIFFLAGS, {ifr_name=3D"foo:", ???}) =3D -1 ENODEV (No su=
ch device)
>=20
>=20
> So, is this fixable or iproute should stop using the ioctl interface?
> (dunno if netlink provides everything already)

Colons are used for the old IP aliasing. IP aliasing was an older way o=
f handling
multiple addresses per interface, and is not necessary anymore. The syn=
tax is
retained for legacy compatibility.