In FTPS, traffic passing through SonicWall will be encrypted and therefore cannot be inspected for malware. For this purpose DPI-SSL can be implemented to enable SonicWall to inspect such traffic in clear text and enforce Security Services.
This article lists the steps required to configure DPI-SSL to inspect FTPS traffic and enforce Gateway Anti-virus (GAV) on such traffic.
When clients behind the SonicWall access an FTPS server on the WAN side of the SonicWall and outbound FTPS connection needs to be decrypted. In this example, we use the default SonicWall DPI-SSL CA certificate.
In the SonicWall management GUI, navigate to the DPI-SSL | Client DPI-SSL page.
Enable check box Enable SSL Client Inspection.
Enable check box Gateway Anti-virus (GAV).
Click on Accept at the top to save the changes.
Other options like including or excluding users, IP addresses are not enabled in this example but can be enabled as per the deployment. Although none of the Security Services except GAV are enabled, all traffic with standard SSL ports as destination will be re-signed by Client DPI-SSL .
Step 3. Configure Server DPI-SSL
When the FTPS server is behind the SonicWall and clients connect to it from the WAN side of the SonicWall. Before configuring Server DPI-SSL we must import a server certificate into the SonicWall. Although the server certificate could be either from a Windows CA or from a public CA like GoDaddy, it is recommended to use a certificate signed by a public CA. Please refer to these articles on how to obtain a server certificate: