Proxy Port application

ppdb

Just wondering, what prevents another user from using the port I've been assigned for my ProxyPort app since TCP/IP sockets don't have permissions.

sean

There's nothing to prevent another user on a shared server from attempting to run a process listening on your assigned port, although in practice I've never seen much of a problem resulting from this.

If your application is running, then nobody else will be able to bind to the port.

If your application isn't running and another user happens to spin up something on its assigned port, then contact our support team so that we can shut it down and deal with the other customer.

ppdb

Thanks Sean.
Webfaction's setup must me more sophisticated than just a simple reverse proxy: they tell me "The ports will be bound to your user, and if someone tries to use the port they will receive an error message that the port is already in use. "
So maybe not an NginX frontend, or some custom software in play.

sean

ppdb I'm pretty sure WF is doing it exactly as we are and that they don't have anything in place to prevent any local user from binding to any unprivileged port that is not in active use by a running application, regardless of who "owns" that port via the control panel assignment.

In other words, the port is assigned to your user, but it's not bound to anything until there is a process that's running and listening on that port.

You can test it yourself at WF:

Create a "custom app listening on port" app or whatever it is they call it.
Create a secondary shell user.
Log in as the secondary shell user and spin up a process on that new port. It works!
Got a second WF account on the same server? Log in to SSH as the primary user on the second account and spin up something on the port from step 1. It works!