OpenSnitch is a GNU/Linux port of the Little Snitch firewall
...You can also convert temporary rules to permanent by right-clicking on a temporary rule or by double-clicking on it, and then edit it. By default OpenSnitch UI listens on a local Unix socket in /tmp/osui.sock.
A POSIX GUI file viewer capable of displaying manual pages and maintaining document meta-data (highlighting and bookmarks) per user per file; a local socket server for easy integration with other software, text can be processed with shell commands.