Micro Focus Enterprise Developer 2.3 for Visual Studio 2015 > General Reference > Mainframe Reference > Micro Focus FTP Utility MFFTP > Writing a Module to Support a Third Party FTP Client > MFFTP Invoking a Third Party Client

MFFTP Invoking a Third Party Client

You need to set the following two environment variables to invoke the client:

Configure MFFTP to use a third party program.
```
MFFTP_CLIENT=USER
```
A user-written module which is specified using MFFTP_USR_FTP_PGM invokes the third party program.
```
MFFTP_USR_FTP_PGM=module
```
This configures MFFTP to call the specified module, that will invoke the third part client.

If MFFTP-CLIENT is set to USER, MFFTP_USR_FTP_PGM must also be set and must name a module that is accessible to the batch process. If these conditions are not met, MFFTP aborts after validating the control cards.