This page documents possible problems with the interaction of SafeTP and firewalls, and known workarounds. Firewalls A firewall is a machine sitting between the Internet and a network of local machines. A firewall's duty is to filter traffic. Typically, a firewall is configured to either permit or block incoming TCP connections, when they are initially established, based on the IP address of the originating machine and the port to which it is trying to connect. Outgoing connections are typically unrestricted.
Some firewalls attempt to understand the content of the data on the connections it allows.
By doing so, the firewall may discover that it should allow connections it otherwise would not, or may try to disallow protocol converstations it doesn't understand. This proves to be the stickiest issue in making SafeTP work with firewalls. FTP and Firewalls Ordinary FTP has a potential problem with firewalls. For this reason, web browsers always use passive transfers. However, dedicated FTP clients usually default to active transfers.