Unknown tunnel mode "vti6"

[Simon Déziel]

[Impact]

Xenial users are unable to create vti6 tunnels.

[Test case]

1) Create a vti6 tunnel
 sudo ip tunnel add vti0 mode vti6 local :: remote fdd6:bdb4:5614::2 key 54
2) No error should be displayed and "ip link" should show a new device named "vti0"

The ip tunnel call currently fails with the error 'Unknown tunnel mode "vti6"' and no tunnel is created.

[Other Info]

vti6 mode is supported according to the man page:

$ man ip-tunnel | grep vti6
       MODE := { ipip | gre | sit | isatap | vti | ip6ip6 | ipip6 | ip6gre | vti6 | any }
                     Modes for IPv6 encapsulation available: ip6ip6, ipip6, ip6gre, vti6, and any.

iproute2 4.9.0-1ubuntu2 on *Artful* has no problem creating vti6 tunnels.

$ lsb_release -rd
Description: Ubuntu 16.04.3 LTS
Release: 16.04
$ apt-cache policy iproute2
iproute2:
  Installed: 4.3.0-1ubuntu3.16.04.3
  Candidate: 4.3.0-1ubuntu3.16.04.3
  Version table:
 *** 4.3.0-1ubuntu3.16.04.3 500
        500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     4.3.0-1ubuntu3.16.04.2 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
     4.3.0-1ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: iproute2 4.3.0-1ubuntu3.16.04.3
ProcVersionSignature: Ubuntu 4.4.0-103.126-generic 4.4.98
Uname: Linux 4.4.0-103-generic x86_64
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
ApportVersion: 2.20.1-0ubuntu2.14
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Dec 9 21:55:27 2017
InstallationDate: Installed on 2016-12-06 (368 days ago)
InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Beta amd64 (20161206)
SourcePackage: iproute2
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.iproute2.rt_tables: [modified]
mtime.conffile..etc.iproute2.rt_tables: 2016-12-21T17:41:32.869321

[Christian Ehrhardt  (paelzer)]

Hi Simon,
we are currently shuffling around responsibilities for iproute so extra latencies might occur :-/.

I have two theories:
1. the iproute package needs fixes that came later than what is in Xenial:
The package needs to be very close to the kernel version in general.
Did you have any chance to test the newer 4.9 by forcing it into a Xenial system if that works as well? If you need a ppa for that let me know and I'll create one for you.

2. the Xenial kernel has this type disabled.
If throwing in an HWE kernel [1] into xenial, does it then work for you?

[1]: https://wiki.ubuntu.com/Kernel/LTSEnablementStack

[Simon Déziel (sdeziel)]

Hello Christian,

On 2017-12-11 10:36 AM, ChristianEhrhardt wrote:
> Hi Simon,
> we are currently shuffling around responsibilities for iproute so extra latencies might occur :-/.

I have no urgent need for this. I was simply experimenting with an
IPv6-only lab.

> 2. the Xenial kernel has this type disabled.
> If throwing in an HWE kernel [1] into xenial, does it then work for you?

The required module (ip6_vti) is in 4.4. Loading it and strace'ing the
ip link I got this:

socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE) = 3
setsockopt(3, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
setsockopt(3, SOL_SOCKET, SO_RCVBUF, [1048576], 4) = 0
bind(3, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(3, {sa_family=AF_NETLINK, pid=1194, groups=00000000}, [12]) = 0
write(2, ""..., 27Unknown tunnel mode "vti6"
) = 27
exit_group(-1) = ?

I get the same on 4.13.0-19-generic from linux-image-virtual-hwe-16.04-edge.

> 1. the iproute package needs fixes that came later than what is in Xenial:
> The package needs to be very close to the kernel version in general.
> Did you have any chance to test the newer 4.9 by forcing it into a Xenial system if that works as well? If you need a ppa for that let me know and I'll create one for you.

As a quick and dirty test, I installed Zesty's debs of iproute2 and
libelf1 on Xenial and that worked with both kernel 4.4 and 4.13.

Thanks,
Simon