Use socket files instead of ports

[acieroid]

The use of ports for services will be confusing, as it might become hard to track which service listens on which port. It would be much easier to use socket files when possible.

[acieroid]

One problem though: we cannot redirect between jails by using socket files. Therefore, I guess we should stay with ports, and maybe have some mechanism to detect port clashes before setting up a service.