diff --git a/src/simtrace_prot.h b/src/simtrace_prot.h
new file mode 100644
index 0000000..878bc34
--- /dev/null
+++ b/src/simtrace_prot.h
@@ -0,0 +1,322 @@
+/* SIMtrace2 USB protocol
+ *
+ * (C) 2015-2017 by Harald Welte <hwelte@hmw-consulting.de>
+ * (C) 2018 by sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
+ */
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/***********************************************************************
+ * COMMON HEADER
+ ***********************************************************************/
+
+enum simtrace_msg_class {
+	SIMTRACE_MSGC_GENERIC = 0,
+	/* Card Emulation / Forwarding */
+	SIMTRACE_MSGC_CARDEM,
+	/* Modem Control (if modem is attached next to device) */
+	SIMTRACE_MSGC_MODEM,
+	/* Reader/phone-car/SIM communication sniff */
+	SIMTRACE_MSGC_SNIFF,
+
+	/* first vendor-specific request */
+	_SIMTRACE_MGSC_VENDOR_FIRST = 127,
+};
+
+enum simtrace_msg_type_generic {
+	/* Generic Error Message */
+	SIMTRACE_CMD_DO_ERROR	= 0,
+	/* Request/Response for simtrace_board_info */
+	SIMTRACE_CMD_BD_BOARD_INFO,
+};
+
+/* SIMTRACE_MSGC_CARDEM */
+enum simtrace_msg_type_cardem {
+	/* TPDU Data to be transmitted to phone */
+	SIMTRACE_MSGT_DT_CEMU_TX_DATA = 1,
+	/* Set the ATR to be returned at phone-SIM reset */
+	SIMTRACE_MSGT_DT_CEMU_SET_ATR,
+	/* Get Statistics Request / Response */
+	SIMTRACE_MSGT_BD_CEMU_STATS,
+	/* Get Status Request / Response */
+	SIMTRACE_MSGT_BD_CEMU_STATUS,
+	/* Request / Confirm emulated card insert */
+	SIMTRACE_MSGT_DT_CEMU_CARDINSERT,
+	/* TPDU Data received from phomne */
+	SIMTRACE_MSGT_DO_CEMU_RX_DATA,
+	/* Indicate PTS request from phone */
+	SIMTRACE_MSGT_DO_CEMU_PTS,
+};
+
+/* SIMTRACE_MSGC_MODEM */
+enum simtrace_msg_type_modem {
+	/* Modem Control: Reset an attached modem */
+	SIMTRACE_MSGT_DT_MODEM_RESET = 1,
+	/* Modem Control: Select local / remote SIM */
+	SIMTRACE_MSGT_DT_MODEM_SIM_SELECT,
+	/* Modem Control: Status (WWAN LED, SIM Presence) */
+	SIMTRACE_MSGT_BD_MODEM_STATUS,
+};
+
+/* SIMTRACE_MSGC_SNIFF */
+enum simtrace_msg_type_sniff {
+	/* Status change (card inserted, reset, ...) */
+	SIMTRACE_MSGT_SNIFF_CHANGE = 0,
+	/* Fi/Di baudrate change */
+	SIMTRACE_MSGT_SNIFF_FIDI,
+	/* ATR data */
+	SIMTRACE_MSGT_SNIFF_ATR,
+	/* PPS (request or response) data */
+	SIMTRACE_MSGT_SNIFF_PPS,
+	/* TPDU data */
+	SIMTRACE_MSGT_SNIFF_TPDU,
+};
+
+/* common message header */
+struct simtrace_msg_hdr {
+	uint8_t msg_class;	/* simtrace_msg_class */
+	uint8_t msg_type;	/* simtrace_msg_type_xxx */
+	uint8_t seq_nr;
+	uint8_t slot_nr;	/* SIM slot number */
+	uint16_t _reserved;
+	uint16_t msg_len;	/* length including header */
+	uint8_t payload[0];
+} __attribute__ ((packed));
+
+/***********************************************************************
+ * Capabilities
+ ***********************************************************************/
+
+/* generic capabilities */
+enum simtrace_capability_generic {
+	/* compatible with 5V SIM card interface */
+	SIMTRACE_CAP_VOLT_5V,
+	/* compatible with 3.3V SIM card interface */
+	SIMTRACE_CAP_VOLT_3V3,
+	/* compatible with 1.8V SIM card interface */
+	SIMTRACE_CAP_VOLT_1V8,
+	/* Has LED1 */
+	SIMTRACE_CAP_LED_1,
+	/* Has LED2 */
+	SIMTRACE_CAP_LED_2,
+	/* Has Single-Pole Dual-Throw (local/remote SIM) */
+	SIMTRACE_CAP_SPDT,
+	/* Has Bus-Switch (trace / MITM) */
+	SIMTRACE_CAP_BUS_SWITCH,
+	/* Can read VSIM via ADC */
+	SIMTRACE_CAP_VSIM_ADC,
+	/* Can read temperature via ADC */
+	SIMTRACE_CAP_TEMP_ADC,
+	/* Supports DFU for firmware update */
+	SIMTRACE_CAP_DFU,
+	/* Supports Ctrl EP command for erasing flash / return to SAM-BA */
+	SIMTRACE_CAP_ERASE_FLASH,
+	/* Can read the status of card insert contact */
+	SIMTRACE_CAP_READ_CARD_DET,
+	/* Can control the status of a simulated card insert */
+	SIMTRACE_CAP_ASSERT_CARD_DET,
+	/* Can toggle the hardware reset of an attached modem */
+	SIMTRACE_CAP_ASSERT_MODEM_RST,
+};
+
+/* vendor-specific capabilities of sysmocom devices */
+enum simtrace_capability_vendor {
+	/* Can erase a peer SAM3 controller */
+	SIMTRACE_CAP_SYSMO_QMOD_ERASE_PEER,
+	/* Can read/write an attached EEPROM */
+	SIMTRACE_CAP_SYSMO_QMOD_RW_EEPROM,
+	/* can reset an attached USB hub */
+	SIMTRACE_CAP_SYSMO_QMOD_RESET_HUB,
+};
+
+/* SIMTRACE_CMD_BD_BOARD_INFO */
+struct simtrace_board_info {
+	struct {
+		char manufacturer[32];
+		char model[32];
+		char version[32];
+	} hardware;
+	struct {
+		/* who provided this software? */
+		char provider[32];
+		/* name of software image */
+		char name[32];
+		/* (git) version at build time */
+		char version[32];
+		/* built on which machine? */
+		char buildhost[32];
+		/* CRC-32 over software image */
+		uint32_t crc;
+	} software;
+	struct {
+		/* Maximum baud rate supported */
+		uint32_t max_baud_rate;
+	} speed;
+	/* number of bytes of generic capability bit-mask */
+	uint8_t cap_generic_bytes;
+	/* number of bytes of vendor capability bit-mask */
+	uint8_t cap_vendor_bytes;
+	uint8_t data[0];
+	/* cap_generic + cap_vendor */
+} __attribute__ ((packed));
+
+/***********************************************************************
+ * CARD EMULATOR / FORWARDER
+ ***********************************************************************/
+
+/* indicates a TPDU header is present in this message */
+#define CEMU_DATA_F_TPDU_HDR	0x00000001
+/* indicates last part of transmission in this direction */
+#define CEMU_DATA_F_FINAL	0x00000002
+/* incdicates a PB is present and we should continue with TX */
+#define CEMU_DATA_F_PB_AND_TX	0x00000004
+/* incdicates a PB is present and we should continue with RX */
+#define CEMU_DATA_F_PB_AND_RX	0x00000008
+
+/* CEMU_USB_MSGT_DT_CARDINSERT */
+struct cardemu_usb_msg_cardinsert {
+	uint8_t card_insert;
+} __attribute__ ((packed));
+
+/* CEMU_USB_MSGT_DT_SET_ATR */
+struct cardemu_usb_msg_set_atr {
+	uint8_t atr_len;
+	/* variable-length ATR data */
+	uint8_t atr[0];
+} __attribute__ ((packed));
+
+/* CEMU_USB_MSGT_DT_TX_DATA */
+struct cardemu_usb_msg_tx_data {
+	uint32_t flags;
+	uint16_t data_len;
+	/* variable-length TPDU data */
+	uint8_t data[0];
+} __attribute__ ((packed));
+
+/* CEMU_USB_MSGT_DO_RX_DATA */
+struct cardemu_usb_msg_rx_data {
+	uint32_t flags;
+	uint16_t data_len;
+	/* variable-length TPDU data */
+	uint8_t data[0];
+} __attribute__ ((packed));
+
+#define CEMU_STATUS_F_VCC_PRESENT	0x00000001
+#define CEMU_STATUS_F_CLK_ACTIVE	0x00000002
+#define CEMU_STATUS_F_RCEMU_ACTIVE	0x00000004
+#define CEMU_STATUS_F_CARD_INSERT	0x00000008
+#define CEMU_STATUS_F_RESET_ACTIVE	0x00000010
+
+/* CEMU_USB_MSGT_DO_STATUS */
+struct cardemu_usb_msg_status {
+	uint32_t flags;
+	/* phone-applied target voltage in mV */
+	uint16_t voltage_mv;
+	/* Fi/Di related information */
+	uint8_t fi;
+	uint8_t di;
+	uint8_t wi;
+	uint32_t waiting_time;
+} __attribute__ ((packed));
+
+/* CEMU_USB_MSGT_DO_PTS */
+struct cardemu_usb_msg_pts_info {
+	uint8_t pts_len;
+	/* PTS request as sent from reader */
+	uint8_t req[6];
+	/* PTS response as sent by card */
+	uint8_t resp[6];
+} __attribute__ ((packed));
+
+/* CEMU_USB_MSGT_DO_ERROR */
+struct cardemu_usb_msg_error {
+	uint8_t severity;
+	uint8_t subsystem;
+	uint16_t code;
+	uint8_t msg_len;
+	/* human-readable error message */
+	uint8_t msg[0];
+} __attribute__ ((packed));
+
+/***********************************************************************
+ * MODEM CONTROL
+ ***********************************************************************/
+
+/* SIMTRACE_MSGT_DT_MODEM_RESET */
+struct st_modem_reset {
+	/* 0: de-assert reset, 1: assert reset, 2: pulse reset */
+	uint8_t asserted;
+	/* if above is '2', duration of pulse in ms */
+	uint16_t pulse_duration_msec;
+} __attribute__((packed));
+
+/* SIMTRACE_MSGT_DT_MODEM_SIM_SELECT */
+struct st_modem_sim_select {
+	/* remote (1), local (0) */
+	uint8_t remote_sim;
+} __attribute__((packed));
+
+/* SIMTRACE_MSGT_BD_MODEM_STATUS */
+#define ST_MDM_STS_BIT_WWAN_LED		(1 << 0)
+#define ST_MDM_STS_BIT_CARD_INSERTED	(1 << 1)
+struct st_modem_status {
+	/* bit-field of supported status bits */
+	uint8_t supported_mask;
+	/* bit-field of current status bits */
+	uint8_t status_mask;
+	/* bit-field of changed status bits */
+	uint8_t changed_mask;
+} __attribute__((packed));
+
+/***********************************************************************
+ * SNIFF
+ ***********************************************************************/
+
+/* SIMTRACE_MSGT_SNIFF_CHANGE flags */
+#define SNIFF_CHANGE_FLAG_CARD_INSERT (1<<0)
+#define SNIFF_CHANGE_FLAG_CARD_EJECT (1<<1)
+#define SNIFF_CHANGE_FLAG_RESET_ASSERT (1<<2)
+#define SNIFF_CHANGE_FLAG_RESET_DEASSERT (1<<3)
+#define SNIFF_CHANGE_FLAG_TIMEOUT_WT (1<<4)
+/* SIMTRACE_MSGT_SNIFF_ATR, SIMTRACE_MSGT_SNIFF_PPS, SIMTRACE_MSGT_SNIFF_TPDU flags */
+#define SNIFF_DATA_FLAG_ERROR_INCOMPLETE (1<<5)
+#define SNIFF_DATA_FLAG_ERROR_MALFORMED (1<<6)
+#define SNIFF_DATA_FLAG_ERROR_CHECKSUM (1<<7)
+
+/* SIMTRACE_MSGT_SNIFF_CHANGE */
+struct sniff_change {
+	/* SIMTRACE_MSGT_SNIFF_CHANGE flags */
+	uint32_t flags;
+} __attribute__ ((packed));
+
+/* SIMTRACE_MSGT_SNIFF_FIDI */
+struct sniff_fidi {
+	/* Fi/Di values as encoded in TA1 */
+	uint8_t fidi;
+} __attribute__ ((packed));
+
+/* SIMTRACE_MSGT_SNIFF_ATR, SIMTRACE_MSGT_SNIFF_PPS, SIMTRACE_MSGT_SNIFF_TPDU */
+struct sniff_data {
+	/* data flags */
+	uint32_t flags;
+	/* data length */
+	uint16_t length;
+	/* data */
+	uint8_t data[0];
+} __attribute__ ((packed));