Monitor, Block, Control Outgoing Connections from Mac – Freeware Firewall
But what about the outgoing connections. There are may be some outgoing attempts from your computer to the outside, which you may want to block and control, how to do that?
TCPBlock is a freeware and lightweight utility, with which you can prevent selected applications on your computer from opening connections to the network.
TCPBlock is implemented as a loadable kernel module which contains all the blocking logic. You can configure it in the System Preferences TCPBlock preference pane or with the tcpblock command line utility. All the configuration changes are made persistent in a configuration file on the hard disk. At system boot time the TCPBlock kernel extension reads its configuration from disk and is ready to go.