IfIndex is actuallay defined Integer32 (1..2147483647)
Need to fix for Netflow V9 still!
hmo20jul20

--- parse.y	2007-10-24 03:04:10.000000000 +0200
+++ parse.y	2020-07-20 19:58:24.915966000 +0200
@@ -703,7 +703,7 @@
 			$$.ifndx_in = $3;
 			$$.match_what |= FF_MATCH_IFNDX_IN;
 			$$.match_negate |= $2 ? FF_MATCH_IFNDX_IN : 0;
-			if ($$.ifndx_in <= 0 || $$.ifndx_in > 65535) {
+			if ($$.ifndx_in <= 0 || $$.ifndx_in > 2147483647) {
 				yyerror("invalid input interface index");
 				YYERROR;
 			}
@@ -716,7 +716,7 @@
 			$$.ifndx_out = $3;
 			$$.match_what |= FF_MATCH_IFNDX_OUT;
 			$$.match_negate |= $2 ? FF_MATCH_IFNDX_OUT : 0;
-			if ($$.ifndx_out <= 0 || $$.ifndx_out > 65535) {
+			if ($$.ifndx_out <= 0 || $$.ifndx_out > 2147483647) {
 				yyerror("invalid output interface index");
 				YYERROR;
 			}