Proposal to enhance SmartLink

m5kvk

Reposted from

https://community.flexradio.com/discussion/8030611/proposal-to-enhance-smartlink

I'd like to propose that SmartLink and SmartSDR be enhanced to improve the chances of being able to establish a direct connection to a remote Flex radio.

Currently, Smartlink relies on the ham being able to open ports in the firewall that protects the remote network. This requires either: 
- direct control of the firewall; or,
- having UPNP enabled on the firewall.

Unfortunately, UPNP is known to create a security risk and is frowned upon by security professionals (see here for an example explanation). Plus, not everybody has control over the firewall. This leaves a group of hams (myself included) for whom SmartLink cannot be made to work without introducing additional complexity.

In my case, the 6400 sits on a remote LAN behind a firewall/router over which I have control, but which is itself connected to somebody else's LAN rather than direct to the ISP. This is because a non-ham offered to host my remote shack at their farm. I have control over my firewall, but I have no way to influence the settings on their firewall. In addition, they are connected to an ISP that uses CGNAT. 

I could adopt the approach advocated in Tim Ellison's article , but this adds complexity and has its own challenges. Being a network techie, I have been able to implement a Zerotier overlay network to allow me to access my remote LAN from my Mac, iPhone, iPad etc. BUT this solution excludes being able to use the Windows version of SmartSDR to drive the radio because the Windows version of SmartSDR can only either discover a local Flex - i.e. one on the same LAN subnetwork - or use SmartLink. Luckily, being primarliy a Mac user, I use SmartSDR for Mac - which can connect to a radio using a specific IP address - but not everybody is so lucky.

All of this could be avoided if Flex adopted one of the established mechanisms that improve the chances of direct communication. Prominent amongst these are the protocols used by (e.g.) WebRTC; including ICE (Internet Connectivity Establishment).

ICE is a set of protocols and services to allow two end-points (e.g. Flex and SmartSDR) to negotiate the best way to connect - hopefully directly - without requiring any modifications to a firewall. Implementing this approach would have no effect on the simplicity of using SmartLink; in fact it would KI even more SS :-) It would also remove the potential for security lapses that might result from using UPNP or somebody mis-configuring their firewall.

Perhaps Flexradio could explore enhancing SmartSDR and the Flex range to support something like ICE. It's a mature approach that is widely adopted by other applications requiring real-time message transport - e.g. VOIP. WebRTC - and shouldn’t be too difficult to add. (I appreciate that "difficult" is a relative term)