Disabling DHCPv6 requests

[Duane Whitty]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

I use my laptop to connect to various public wireless access points.
One of the networks I regularly connect to wants to configure ipv6.  I
do not want that (ipv6 is disabled).

I get the following message in /var/log/syslog

"Activation (wlan0) Stage 3 of 5 (IP Configure Start) starting DHCPv6 as
requested by IPv6 router..."

I have disabled ipv6 so the request times-out but I would like to know
if there is a method to tell dhclient to send an option in advance to
the ipv6 capable router notifying it that this client isn't doing ipv6
or a response back when it makes the request to start ipv6 configuration
.

Does anyone have any ideas whether this is possible and if so how can
I accomplish said goal?  System details below (XXX to obfuscate):

$ uname -a
Linux XXX 4.2.0-38-generic #45~14.04.1-Ubuntu SMP Thu Jun 9 09:28:50
UTC 2016 i686 i686 i686 GNU/Linux

$ dhclient --version
isc-dhclient-4.2.4

$ ps aux | grep dhclient
root      1704  0.0  0.2   5524  4640 ?        S    13:47   0:00
/sbin/dhclient -d -sf /usr/lib/NetworkManager/nm-dhcp-client.action
- -pf /run/sendsigs.omit.d/network-manager.dhclient-wlan0.pid -lf
/var/lib/NetworkManager/dhclient-XXX-wlan0.lease -cf
/var/lib/NetworkManager/dhclient-wlan0.conf wlan0

NetworkManager (version 0.9.8.8)

XXX NetworkManager[854]: <warn> (wlan0): DHCPv6 request timed out.
XXX NetworkManager[854]: <info> (wlan0): canceled DHCP transaction,
DHCP client pid 2266
XXX NetworkManager[854]: <info> Activation (wlan0) Stage 4 of 5 (IPv6
Configure Timeout) scheduled...
XXX NetworkManager[854]: <info> Activation (wlan0) Stage 4 of 5 (IPv6
Configure Timeout) started...
XXX NetworkManager[854]: <info> Activation (wlan0) Stage 4 of 5 (IPv6
Configure Timeout) complete.

$ /etc/dhcp/dhclient.conf
option rfc3442-classless-static-routes code 121 = array of unsigned
integer 8;
request subnet-mask, broadcast-address, time-offset, routers,
        interface-mtu, rfc3442-classless-static-routes, ntp-servers;

$ /etc/NetworkManager/NetworkManager.conf
[main]
plugins=ifupdown

[ifupdown]
managed=true

$ /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
hostname XXX
dns-nameservers XXX.XXX.XXX.XXX XXX.XXX.XXX.XXX

System is configured to connect to a VPN provider at startup via OpenVPN

$ openvpn --version
OpenVPN 2.3.11 i686-pc-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL]
[PKCS11] [MH] [IPv6] built on May 10 2016
library versions: OpenSSL 1.0.1f 6 Jan 2014, LZO 2.06

I've spent a fair bit of time getting networking working the way I
want and everything is good except for the DHCPv6 configuration request.

Hopefully I've provided the necessary information.  If anyone familiar
with this scenario needs more info please let me know.

Best Regards,
Duane

- -- 
Duane Whitty
duane at nofroth.com
-----BEGIN PGP SIGNATURE-----

iQEcBAEBCAAGBQJX1vWJAAoJEOJfpr8UVxtk6CwH/1hlzNtLsQ/uNNXcP8gAQx+g
D9lFqvv7OSzyaEp66Dl//ZFvrtJr3rHLOjleTBY4AbxrKLUJ0GXmoBoRwKbUznlx
UxyXyizgriWDOHEyRrmmqW5TUQ8vOCqEDoOVdYyQtlfeJuiAahCQOKhNEVt12eVj
u93/8txSi8WKwqYU02k2uwdiMknVxTXaUUkYrERUPS89N45qC/uDt7lJ5zmSde6J
58DFtwcV443sA5kJOI+zfqhJUD7iv74RwllXdkVDwG8OgFlles0QbUbmSi1Fc3fK
28Bz+USdYShGU+v+BNTCpzSg6CCuU9fgD0OMNmN3UOPrQ2oKHJgxxcfdAKvpwFw=
=Ivpk
-----END PGP SIGNATURE-----