TCPBlock For Mac

TCPBlock is a lightweight and fast application firewall for Mac OS X 10.5 or later developed by delantis.com.

The Mac OS X firewall protects you from connections that come from outside of your computer. But what about the software from your computer that opens new connections to the internet? With TCPBlock 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.

In System Preferences open the TCPBlock preference pane. You can choose to enable the firewall, to block all connections to the network and you can specify if your application list is a black list or a white list.

Use the + button to add new applications to the list. Here you must type the unix command name of the application. To get the command name open a Terminal and type "/usr/local/bin/tcpblock -m" to start the TCPBlock network monitor.

As soon as your application tries to establish a network connection it is listed in the network monitor. Copy the application name from the network monitor and paste it into the preference pane application list.

Note that, due to the limited knowledge of filenames in the Mac OS X kernel only the first 16 characters of the command name are used for name comparations. Any characters above this limit are truncated.

Use the command line client /usr/local/bin/tcpblock to configure TCPBlock or to monitor its activities.

To list all the available options use the command tcpblock -h.

The TCPBlock configuration is stored in the file /etc/tcpblock.conf. If you edit this file then execute tcpblock -c to load the changed configuration. This file is overwritten if you configure TCPBlock with the preference pane or the tcpblock utility.