--- a/packages/devs/eth/synth/ecosynth/current/ChangeLog
+++ b/packages/devs/eth/synth/ecosynth/current/ChangeLog
@@ -1,3 +1,11 @@
+2003-04-08  Andrew Lunn  <lunn@londo>
+
+	* host/rawether.c (tap_init): Set the persistent flag on the tap
+	device if requested by the user. This allows dhcpd and radvd to
+	keep running on the tap device between invocations of the synth
+	target.	
+	* doc/syntheth.sgml: Documentation for the persistent option.
+
 2003-04-01  Andrew Lunn  <andrew.lunn@ascom.ch>
 
 	* src/syntheth.c (synth_eth_init): Set the flag IFF_ALLMULTI when

--- a/packages/devs/eth/synth/ecosynth/current/doc/syntheth.sgml
+++ b/packages/devs/eth/synth/ecosynth/current/doc/syntheth.sgml
@@ -339,6 +339,30 @@ address information. Instead the eCos co
 or static addresses.
     </para>
     <para>
+When <command>rawether</command> exits, the tap interface is removed
+by the kernel. By adding the parameter persistent
+<command>rawether</command> will set the persistent flag on the tap
+device.
+    </para>
+    <programlisting>
+synth_device ethernet {
+    eth0 ethertap tap3 00:01:02:03:FE:05
+    eth1 ethertap tap4 00:01:02:03:FE:06 persistent
+    &hellip;
+}
+</programlisting>
+    <para>
+With this flag set the kernel will not remove the interface when
+<command>rawether</command> exits. This means applications such as
+<command>dhcpd</command>, <command>radvd</command>, and
+<command>tcpdump</command> will continue to run on the interface
+between invocations of synthetic targets. As a result the target can
+dynamically obtain its IP addresses from these daemons. Note it is a
+good idea to specify a MAC address otherwise a different random MAC
+address will be used each time and the dhcpd daemon will not be able
+to reissue the same IP address.
+    </para>
+    <para>
 An alternative approach would be to set up the Linux box as a network
 bridge, using commands like <command>brctl</command> to connect the
 virtual network interface <varname>tap3</varname> to a physical

--- a/packages/devs/eth/synth/ecosynth/current/host/ethernet.tcl
+++ b/packages/devs/eth/synth/ecosynth/current/host/ethernet.tcl
@@ -165,7 +165,7 @@ namespace eval ethernet {
 	# Do some validation here, before the rawether process is started.
 	# Typical entries would look like
 	#     eth0 real eth1
-	#     eth1 ethertap [[tap-device] [MAC]]
+	#     eth1 ethertap [[tap-device] [MAC] [persistent]]
 	set junk ""
 	set optional ""
 	set mac      ""
@@ -176,7 +176,7 @@ namespace eval ethernet {
 		if { ! [regexp -- {^tap[0-9]+\s*(.*)$} $optional junk mac ] } {
 		    synth::report_error "Cannot instantiate ethernet device $name\n   \
 			    Invalid entry \"$use\" in target definition file $synth::target_definition\n   \
-			    Should be \"ethertap \[<tap-device> \[<MAC address>\]\]\"\n"
+			    Should be \"ethertap \[<tap-device> \[<MAC address>\]\] [persistent]\"\n"
 		    return ""
 		}
 		if { "" != $mac } {

--- a/packages/devs/eth/synth/ecosynth/current/host/rawether.c
+++ b/packages/devs/eth/synth/ecosynth/current/host/rawether.c
@@ -32,7 +32,7 @@
 //#####DESCRIPTIONBEGIN####
 //
 // Author(s):   bartv
-// Contact(s):  bartv
+// Contact(s):  bartv, andrew.lunn@ascom.ch
 // Date:        2002/08/07
 // Version:     0.01
 // Description:
@@ -525,6 +525,8 @@ tap_init(int argc, char** argv)
 {
     char* devname   = NULL;
     struct ifreq    ifr;
+    int persistent  = 0;
+    int have_mac    = 0;
 
     tx_fn           = &tap_handle_tx;
     rx_fn           = &tap_handle_rx;
@@ -542,31 +544,46 @@ tap_init(int argc, char** argv)
     // but the user can specify one to avoid a source of randomness.
     // This MAC address is not actually needed by any of the code here,
     // but should be returned to eCos.
-    if (2 == argc) {
+    if (2 <= argc) {
         unsigned int mac_data[6];   // sscanf() needs unsigned ints
-        int result = sscanf(argv[1], "%x:%x:%x:%x:%x:%x",
-                            &(mac_data[0]), &(mac_data[1]), &(mac_data[2]),
-                            &(mac_data[3]), &(mac_data[4]), &(mac_data[5]));
-        if (6 != result) {
-            snprintf(msg, MSG_SIZE, "Invalid MAC address %s\n", argv[1]);
-            report_error(msg);
-        }
-        MAC[0] = mac_data[0];
-        MAC[1] = mac_data[1];
-        MAC[2] = mac_data[2];
-        MAC[3] = mac_data[3];
-        MAC[4] = mac_data[4];
-        MAC[5] = mac_data[5];
-    } else {
-        srand(time(NULL));
-        MAC[0] = 0;
-        MAC[1] = 0x0FF;
-        MAC[2] = rand() & 0x0FF;
-        MAC[3] = rand() & 0x0FF;
-        MAC[4] = rand() & 0x0FF;
-        MAC[5] = rand() & 0x0FF;
+	int result = sscanf(argv[1], "%x:%x:%x:%x:%x:%x",
+			    &(mac_data[0]), &(mac_data[1]), &(mac_data[2]),
+			    &(mac_data[3]), &(mac_data[4]), &(mac_data[5]));
+	if (6 != result) {
+	  if (strncmp(argv[1], "persistent", 10)) {
+	    snprintf(msg, MSG_SIZE, "Invalid MAC address %s\n", argv[1]);
+	    report_error(msg);
+	  } 
+	} else {
+	  MAC[0] = mac_data[0];
+	  MAC[1] = mac_data[1];
+	  MAC[2] = mac_data[2];
+	  MAC[3] = mac_data[3];
+	  MAC[4] = mac_data[4];
+	  MAC[5] = mac_data[5];
+	  argv += 1;
+	  argc -= 1;
+	  have_mac = 1;
+	}
+    } 
+    if ( 1 != have_mac) {
+      srand(time(NULL));
+      MAC[0] = 0;
+      MAC[1] = 0x0FF;
+      MAC[2] = rand() & 0x0FF;
+      MAC[3] = rand() & 0x0FF;
+      MAC[4] = rand() & 0x0FF;
+      MAC[5] = rand() & 0x0FF;
     }
 
+    // Should we make the TAP device persistent. When persistence is
+    // enabled, the tap device is not removed when rawether
+    // exits. This makes daemons happier. They can keep running
+    // between invocations of rawether.
+    if (2 <= argc ) {
+      persistent = !strncmp(argv[1], "persistent", 10);
+    }
+    
     ether_fd = open("/dev/net/tun", O_RDWR);
     if (ether_fd < 0) {
         snprintf(msg, MSG_SIZE, "Failed to open /dev/net/tun, errno %s (%d)\n", (errno < sys_nerr) ? sys_errlist[errno] : "<unknown>", errno);
@@ -586,6 +603,14 @@ tap_init(int argc, char** argv)
     // Supporting multicasts is a no-op
     multicast_supported = 1;
     
+    if (persistent) {
+      if (ioctl(ether_fd, TUNSETPERSIST, 1) < 0) {
+	snprintf(msg, MSG_SIZE, "Failed to set persistent flag, errno %s (%d)\n",
+		 ( errno < sys_nerr) ? 
+		 sys_errlist[errno] : "<unknown>", errno);
+	report_error(msg);
+      }
+    }
     // All done.
 }
 #else
@@ -770,3 +795,4 @@ main(int argc, char**argv)
     return 0;
 }
 
+