[cap-talk] Simple Cooperative File Sharing (SCoopFS), the "F" is silent

Stiegler, Marc D marc.d.stiegler at hp.com
Fri Mar 13 03:16:21 EDT 2009


> > I think this is great progress.  I skimmed some of it.  Do 
> you have to 
> > open port 443 on your router/firewall?
> 
> We assume 443 is open because so much other stuff breaks if it isn't.

John may be referring to the firewall on the box, not on the network. Some organizations and some systems come configured to prevent the user from turning on servers on his own box: Vista as configured by HP, for example, configures the firewall to not allow applications like waterken from configuring the port. The current installation instructions for SCoopFS explain how to repair your Vista firewall configuration.

For going across the network, SCoopFS uses 2 pieces of machinery that are outside the firewalls, on the internet.

The first is Tyler's yurl server, which runs a redirectory: when a waterken server comes up, it registers its current ip address with the yurl server. When another waterken server wants to set up a connection, it hits the yurl server for an ip address. The most that is ever required of a server/computer to re-establish its connections after moving from one place to another is to restart the server, to force a re-register.

The second service is the Fred, which is a crude store-and-forwarder that I wrote as a waterken application. In SCoopFS, servers do not actually talk directly to each other. Rather, every message is passed to the Fred. The recipient, who might be behind a firewall, periodically polls the Fred for pending messages. Hence, with respect to network firewalls, the only cooperation we need from them is that they allow computers inside the firewall to use https protocol as clients to communicate with servers outside the firewall (the Fred-oriented SCoopFS app behaves as a client-side entity). As a practical matter, all network firewalls allow client-side https connections to the web -- otherwise you couldn't use gmail :-)

--marcs 



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