diff --git a/src/sim/main.c b/src/sim/main.c
index 91cae4b..17ebb32 100644
--- a/src/sim/main.c
+++ b/src/sim/main.c
@@ -41,6 +41,7 @@
 int num_kanal = 1;
 sim_sniffer_t sim_sniffer;
 sim_sim_t sim_sim;
+const char *write_pdu_file = NULL;
 static int quit = 0;
 static const char *serialdev = "/dev/ttyUSB0";
 static int baudrate = 9600;
@@ -80,6 +81,8 @@ void print_help(const char *arg0)
 	printf("        Serial device (default = '%s')\n", serialdev);
 	printf(" -b --baud-rate <baud>\n");
 	printf("        Serial baud rate (default = %d)\n", baudrate);
+	printf(" -w --write-pdu <filename>\n");
+	printf("        Write PDU to file (sniffer only)\n");
 	printf("\nSIM card simulator options:\n");
 	printf(" -E --eeprom <name>\n");
 	printf("        Stores and reads EEPROM data to/from file. The file is stored at\n");
@@ -120,6 +123,7 @@ void add_options(void)
 	option_add('v', "debug", 1);
 	option_add('s', "serial-device", 1);
 	option_add('b', "baud-rate", 1);
+	option_add('w', "write-pdu", 1);
 	option_add('E', "eeprom", 1);
 	option_add('F', "futln", 1);
 	option_add(OPT_SICHERUNG, "sicherung", 1);
@@ -156,6 +160,9 @@ int handle_options(int short_option, int argi, char **argv)
 	case 'b':
 		baudrate = atoi(argv[argi]);
 		break;
+	case 'w':
+		write_pdu_file = options_strdup(argv[argi]);
+		break;
 	case 'E':
 		eeprom_name = options_strdup(argv[argi]);
 		break;
diff --git a/src/sim/sniffer.c b/src/sim/sniffer.c
index 728af53..f635246 100644
--- a/src/sim/sniffer.c
+++ b/src/sim/sniffer.c
@@ -26,6 +26,8 @@
 #include "sim.h"
 #include "sniffer.h"
 
+extern const char *write_pdu_file;
+
 /* Layer 7 */
 
 static void rx_icl_sdu(uint8_t *data, int length)
@@ -742,9 +744,18 @@ static void rx_char(sim_sniffer_t *sim, uint8_t c)
 		else
 			PDEBUG(DSIM2, DEBUG_INFO, " control unknown 0x%02x\n", sim->block_control);
 		PDEBUG(DSIM2, DEBUG_INFO, " length %d\n", sim->block_length);
-		if (sim->block_checksum == 0)
+		if (sim->block_checksum == 0) {
+			FILE *fp;
+			if (write_pdu_file && (fp = fopen(write_pdu_file, "a"))) {
+				int i;
+				fprintf(fp, "PDU: addr=0x%02x ctrl=0x%02x len=0x%02x data:", sim->block_address, sim->block_control, sim->block_length);
+				for (i = 0; i < sim->block_length; i++)
+					fprintf(fp, " 0x%02x", sim->block_data[i]);
+				fprintf(fp, "\n");
+				fclose (fp);
+			}
 			rx_icl_pdu(sim->block_data, sim->block_length);
-		else
+		} else
 			PDEBUG(DSIM2, DEBUG_NOTICE, "Received message with checksum error!\n");
 		sim->block_state = BLOCK_STATE_ADDRESS;
 	}