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FreeRDP implements smartcard redirection using the [MS-RDPESC] Smart Card Virtual Channel Extension. The smartcard device is transported as an RDPDR_DTYP_SMARTCARD device over the rdpdr SVC, allowing applications on the RDP server to use PCSC-connected smartcards on the client machine. Channel: rdpdr (Device Redirection Virtual Channel)
Device type: RDPDR_DTYP_SMARTCARD Client implementation: channels/smartcard/client/
Header: <winpr/smartcard.h> (WinPR PCSC abstraction)

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Build Requirements

Smartcard redirection requires PC/SC middleware headers and libraries. 
# Install PC/SC development package (Debian/Ubuntu)
apt install libpcsclite-dev

# Enable at cmake configure time
cmake -DWITH_PCSC=ON ..
On macOS, the system PCSC framework (PCSC/winscard.h) is used automatically when WITH_PCSC=ON.

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Activating Smartcard Redirection

Enable the smartcard device on the client via the command line: 
# Redirect smartcard(s)
xfreerdp /smartcard /v:server

# Equivalent explicit form
xfreerdp /device:scard,smartcard /v:server
The rdpdr client plugin detects the /smartcard option and registers a SMARTCARD_DEVICE entry in the device list that gets announced to the server.

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SMARTCARD_DEVICE Structure

typedef struct {
    DEVICE             device;         /* base RDPDR device (must be first) */
    HANDLE             thread;         /* IRP processing thread */
    scard_call_context* callctx;       /* PCSC call context */
    wMessageQueue*     IrpQueue;       /* incoming IRP queue */
    wListDictionary*   rgOutstandingMessages; /* in-flight IRP map */
    rdpContext*        rdpcontext;
} SMARTCARD_DEVICE;
Each SMARTCARD_CONTEXT represents one active PCSC context opened by a server application: 
typedef struct {
    HANDLE           thread;
    SCARDCONTEXT     hContext;  /* PCSC context handle */
    wMessageQueue*   IrpQueue;
    SMARTCARD_DEVICE* smartcard;
} SMARTCARD_CONTEXT;

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Server-Side Callbacks (via RdpdrServerContext)

The server side uses the RdpdrServerContext smartcard hooks from <freerdp/server/rdpdr.h>:
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OnSmartcardCreate
psRdpdrOnDeviceCreate
typedef UINT (*psRdpdrOnDeviceCreate)(RdpdrServerContext* context,
                                     const RdpdrDevice* device);
Called when a smartcard device (RDPDR_DTYP_SMARTCARD) is announced by the client. The server can record device->DeviceId and open a PCSC context targeting the redirected reader.
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OnSmartcardDelete
psRdpdrOnDeviceDelete
typedef UINT (*psRdpdrOnDeviceDelete)(RdpdrServerContext* context, UINT32 deviceId);
Called when the smartcard device is removed (card pulled, channel disconnected).

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Protocol Flow

1

Device announcement

The RDPDR client plugin announces the smartcard as RDPDR_DTYP_SMARTCARD. The server’s OnSmartcardCreate callback fires.
2

PCSC context setup

Server applications call SCardEstablishContext() which the WinPR PCSC shim translates to [MS-RDPESC] Establish_Call IRPs forwarded to the client.
3

Card operations

Each PCSC call (SCardConnect, SCardTransmit, SCardBeginTransaction, etc.) becomes an IRP. The client executes the call against the real local PCSC daemon and returns the result.
4

Tear-down

SCardReleaseContext() triggers a Release_Call IRP. When the RDPDR channel closes, OnSmartcardDelete fires and all outstanding contexts are cleaned up.

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Supported PCSC Operations

The FreeRDP smartcard channel supports the full [MS-RDPESC] operation set including:
  • SCardEstablishContext / SCardReleaseContext
  • SCardConnect / SCardReconnect / SCardDisconnect
  • SCardBeginTransaction / SCardEndTransaction
  • SCardTransmit — APDUs for card communication
  • SCardStatus / SCardGetStatusChange
  • SCardListReaders / SCardListCards
  • SCardGetAttrib / SCardSetAttrib
Smartcard redirection requires the server OS to have the WinPR PCSC bridge active. On Windows Server this is native; on Linux the FreeRDP scard-emulator or a compatible PCSC daemon must be present.
To verify the redirected reader is visible after connecting, run pcsc_scan or opensc-tool -l in the remote session.