Hello everyone, this is my first bug report, I'm newbie on Arch community.

Description:

When NetworkManager tries to connect in a wifi with IPv6, it's hangs and stop working. You can't even cancel the connection. This is due to dhcpcd, the default DHCP of NetworkManager, which doesn't support IPv6. This bug is well know: it's described on Arch Wiki[1] and on NetworkManager bugtracker[2]. Whoever, as seen here[2], the NetworkManager team doesn't look like to be interested on dropping dhcpcd.

To solve this, one need to change the default dhcp used on NetworkManager, as described here[1], e.g. using dhclient (which already is a dependence to install NetworkManager).

Couldn't we pack NetworkManager with the following change?

* Set NetworkManager.conf[3] to something like this:

# Configuration file for NetworkManager.
# See "man 5 NetworkManager.conf" for details.
[main]
dhcp=dhclient

(Although the fix here[1] instructs to change /etc/NetworkManager/conf.d/dhcp-client.conf, here it worked on /etc/NetworkManager/NetworkManager.conf)

Additional info:
* NetworkManager 1.12.3dev+1+g0a3755c17-1
* dhcpcd 7.0.7
* isc-dhclient-4.4.1
* A log of NetworkManager hanging on dhcpcd timeout is attached

Steps to reproduce:

* Using NetworkManager with default configuration, try to connect to a wifi router using IPv6;
* Then your network applications will hang.

Steps to fix manually:

* Remove the file corresponding to the SSID which you tried to connect to;
* Restart the NetworkManager service (or reboot your system);
* If insn't already installed, install dhclient;
* Add the following lines on /etc/NetworkManager/NetworkManager.conf:
[main]
dhcp=dhclient
* Restart the NetworkManager service.

Please let me know if (and why) you disagree and where I can report this if here isn't the appropriated place. Thanks!

[1] https://wiki.archlinux.org/index.php/NetworkManager#IPv6
[2] https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/5
[3] https://git.archlinux.org/svntogit/packages.git/tree/trunk?h=packages/networkmanager