USB redirection in HDX mode

Most applications that support USB device redirerection have a default policy that is pretty good at anticipating typical USB redirection requirements, so you will rarely need to alter this. In TLXOS 4.8.0 or later - with TMS 8.2.0 or later if using TMS - you can override the default security policy to explicitly allow or deny redirection of specific USB devices (with some limitations, e.g. USB mice, keyboards and hubs can never be redirected) using the "Show Overrides" button.  In older versions of TLXOS, you must make manual alternations to application preference files.

Typically, the only situation in which you will need to alter the client-side HDX USB redirection policy is when your USB device presents as a compound USB device, i.e. contains several subdevices, some of which are blocked by the default policy.  For example, many smart phones have HID devices that the default policy will block.  On the Raspberry Pi platform you may also need to alter the policy relating to USB audio devices, because the ARM port of RTME is not yet available (to ThinLinX, anyway).

The Citrix Workspace App USB redirection policy file is located in /opt/Citrix/ICAClient/usb.conf.  This is used by the ctxusbd daemon (and systemd service of the same name).  The default policy basically blocks mice, keyboards, USB hubs, audio devices, modems, smartcard readers, and some (but not all) WiFi and USB ethernet devices, and allows everything else.

In order to override the default policy for a particular USB device, you need to add an ALLOW line to the /opt/Citrix/ICAClient/usb.conf file, above the first of the DENY lines, for the specific USB vendor and product ID of your device.  You can obtain these by opening a local terminal window and entering "lsusb".  For example, an ALLOW line for an iPhone 4S would look like:

ALLOW: vid=05ac, pid=12a0

To do this, you will need to SSH as root to your TLXOS device (see the separate Knowledgebase article on this subject).  Run "systemctl restart ctxusbd" after making the change.