Set all builds to have UPNP disabled by default

[IngCr3at1on]

this at least builds in gitian (1 hour) and partly addresses #264

[jpass022]

Why would you want upnp disabled by default? I think this will just cause problems for normal users...

[IngCr3at1on]

#264

You'll find that even though they've updated the UPNP version for bitcoin they have disabled it be default on bitcoin as well to avoid possible issues like the above mentioned in the future.

The vulnerability really only effects nodes on a public LAN and as I understand it it does not allow access to the wallet it's more a stability issue but having a potentially vulnerable or vulnerable function enabled by default isn't always the best option (even if it does make things easier for some people).

[dbroyhill]

Does disabling UPNP require users to perform additional steps, such as adding exceptions to their firewalls and opening ports on their routers?

[IngCr3at1on]

Possibly in some cases, otherwise they may not need to as that will only effect incomming connections. A wallet can function with nothing but outgoing connections (I've done that with a few daemons at different points).

If a user finds they have issues with the connections with UPNP disabled they can either open ports or enable UPNP in their conf or when starting the wallet. This doesn't remove UPNP it just changes it from being Opt-Out (which is potentially unsafe) to being Opt-In (requiring at least some minor education and responsibility on the users part).

[CeForce]

We've had scenarios in support where we have had to help or direct users to open their firewall ports even when UPNP enabled. If it's still going to only impact the occasional or a small % of users it makes sense to set the default to UPNP disabled.

I'd rather see something a little more inherently secure be the default and it require a user action to change that status.

[IngCr3at1on]

This has been rebased over master do to merge conflicts (5 minutes)

[MitchellCash]

utACK to making it disabled by default