[Lazarus] File sync system approach

[Lukasz Sokol]

On 09/07/15 14:22, aradeonas wrote:
> Yes,not only but big question.
> Im reading about SFTP but it seems not to be a good choice for something
> like OwnCloud or DropBox or ... .
> 

>From the idea these systems work like, you'd need a bilateral IP connection
from one end to the other, and then (S)FTP protocol working on that,
much like OpenVPN or IPSec does, and then some 'automatic' discovery of
either end... 

Usually for hassle-free establishing of such anonymous tunnel over NATs and firewalls, 
a helper publicly-available server is required;
In such manner, either end first try to contact the public server and then 
the public server passes the either-end info around and makes them 'mate' together
(much alike Teamviewer or Skype works)

Why?
For either end may be behind NAT or restrictive firewall;
Also some NAT/Router/Firewall/Office Gateway solutions tend to run 
weird port masking/protection schemes; or NAT-T; and then there is the weird (and wonderful...)
world of UPNP, where you can request a WAN port of your internet gateway
to be forwarded to a port you listen on (in an ideal world, more often than not
it ends up being abused by NAS devices that tend to hijack your WAN's port 80 or 443...)


> Regards,
> Ara
> 
> 
el es