Flop

Flop is a simple and portable program for copying files over network. It uses only one standard TCP/IP connection for the transfer, and can be configured to use any port, thus making it possible to it over many firewalls. Due to its simple protocol, flop is also very efficient.

Flop compiles directly on Windows NT/95 (with Watcom C), and on Linux, Solaris and Digital Unix with GCC. Porting it to other platforms and compilers should be trivial, as long as standard BSD sockets are available. Both the C source code and a Win32 binary are available for download here.

A development version of flop 2 is also available. It adds support for transferring multiple files and streaming to/from stdin/out. The final version should also have support for opening the connection from receiver to sender (passive mode, so to speak), but this isn't implemented yet. Flop2 is available as C source code and Win32 binary. To compile flop2 under Win32 you also need a small wildcard expansion library.

Flop is written and maintained by Petteri Kangaslampi, pekangas@sci.fi.