The usual ways to do that are to open a connection to the things you need at startup, and then drop your privileges, set ulimits or whatever. Or you don't have

The usual ways to do that are to open a connection to the things you need at startup, and then drop your privileges, set ulimits or whatever. Or you don't have network access at all, but pipe your logs to a local process that does. Alternatively the application can be made to have some OS-specific rules to e.g. generate iptables rules on Linux, so it can contacts its logger, but not anything else. All of those are probably anathema to the typical Java programmer though, as they require crossing the boundary from JVM into OS configuration.