VMware Horizon Client Architecture : 4.5 Device Redirection : 4.5.1 Client Drive Redirection
   
4.5.1 Client Drive Redirection
Client Drive Redirection (CDR) is useful for users that wish to redirect a local or network drives from the client to the virtual desktop or application. File type association also allows for local files to launch the virtual application rather than local instance of the application. This setting can either be enabled/disabled by the client or enforced by the administrator via a client Group Policy Object (GPO), at a server level or farm wide. CDR is supported on Windows, Mac OS and Linux clients.
Figure 6. Accessing local drives with CDR
 
As described in the previous section, when Blast Extreme is used as the remote / client protocol, CDR will be established inside a View Virtual Channel (VVC) over HTTPS (TCP 443). If HTTPS Secure Tunnel is not configured, CDR will use TCP 9427 between the client and server.
For external client connections (internet) it is recommended to use the VVC for CDR since it uses the existing HTTPS 443 connection, eliminating the need to open another firewall port.