[Yaniv Kaul <ykaul@xxxxxxxxxxxx>]

This small patch looks at the first byte of the dst_addr, and if it's 
'i', 'I', 'o', or 'O', it will interpret the file as FW1 monitor file, 
if the automatic check for it was enabled in the preferences.

Index: packet-eth.c
===================================================================
--- packet-eth.c	(revision 12561)
+++ packet-eth.c	(working copy)
@@ -41,6 +41,7 @@
 
 /* Interpret capture file as FW1 monitor file */
 static gboolean eth_interpret_as_fw1_monitor = FALSE;
+static gboolean eth_auto_fw1_monitor = FALSE;
 
 /* protocols and header fields */
 static int proto_eth = -1;
@@ -277,6 +278,13 @@
     if (eth_interpret_as_fw1_monitor) {
       call_dissector(fw1_handle, tvb, pinfo, tree);
       goto end_of_eth;
+    } 
+    else
+    if (eth_auto_fw1_monitor) {
+	if((dst_addr[0] == 0x69) || (dst_addr[0] == 0x49) || (dst_addr[0] == 0x6f) || (dst_addr[0] == 0x4f)) {
+		call_dissector(fw1_handle, tvb, pinfo, tree);
+		goto end_of_eth;
+	}
     }
 
     if (check_col(pinfo->cinfo, COL_INFO))
@@ -450,6 +458,7 @@
             "Interpret as FireWall-1 monitor file",
 "Whether the capture file should be interpreted as a CheckPoint FireWall-1 monitor file",
             &eth_interpret_as_fw1_monitor);
+	prefs_register_bool_preference(eth_module, "auto_fw1_monitor", "Automatically interpret as FireWall-1 monitor file", "Whether the capture file should be automatically interpreterd as a Check Point FireWall-1 monitor file", &eth_auto_fw1_monitor);
 
 	register_dissector("eth", dissect_eth, proto_eth);
 	eth_tap = register_tap("eth");