diff -ruN migrationtools-47.orig/migrate_common.ph migrationtools-47/migrate_common.ph
--- migrationtools-47.orig/migrate_common.ph	2007-01-10 22:20:42.000000000 +0100
+++ migrationtools-47/migrate_common.ph	2007-01-10 22:35:26.000000000 +0100
@@ -92,6 +92,14 @@
 # such as person.
 $EXTENDED_SCHEMA = 0;
 
+# Uncomment these to exclude system users and groups
+#$IGNORE_UID_BELOW = 1000;
+#$IGNORE_GID_BELOW = 1000;
+
+# And here's the opposite for completeness
+#$IGNORE_UID_ABOVE = 65535;
+#$IGNORE_GID_ABOVE = 65499;
+
 #
 # allow environment variables to override predefines
 #
diff -ur MigrationTools-47/migrate_group.pl MigrationTools-47-minmax-ugid/migrate_group.pl
--- MigrationTools-47/migrate_group.pl	2007-11-07 17:52:40.000000000 +0100
+++ MigrationTools-47-minmax-ugid/migrate_group.pl	2007-11-07 17:50:15.000000000 +0100
@@ -41,6 +41,28 @@
 $PROGRAM = "migrate_group.pl";
 $NAMINGCONTEXT = &getsuffix($PROGRAM);
 
+if ($#ARGV < 0) {
+	print STDERR "Usage: $PROGRAM [--mingid N] [--maxgid M] infile [outfile]\n";
+	exit 1;
+}
+
+if ( defined($IGNORE_GID_BELOW) ) {
+	$mingid = $IGNORE_GID_BELOW;
+}
+if ( defined($IGNORE_GID_ABOVE) ) {
+	$maxgid = $IGNORE_GID_ABOVE;
+}
+while ($ARGV[0] =~ /^--.*/) {
+	if ($ARGV[0] eq "--mingid") {
+		$mingid = $ARGV[1];
+		shift ; shift;
+	} elsif ($ARGV[0] eq "--maxgid") {
+		$maxgid = $ARGV[1];
+		shift ; shift;
+	} else {
+		shift;
+	}
+}
 &parse_args();
 &open_files();
 
@@ -51,6 +67,8 @@
 	next if /^\+/;
 
 	local($group, $pwd, $gid, $users) = split(/:/);
+	next if (defined($mingid) and ($gid < $mingid));
+	next if (defined($maxgid) and ($gid > $maxgid));
 	
 	if ($use_stdout) {
 		&dump_group(STDOUT, $group, $pwd, $gid, $users);
diff -ur MigrationTools-47/migrate_passwd.pl MigrationTools-47-minmax-ugid/migrate_passwd.pl
--- MigrationTools-47/migrate_passwd.pl	2007-11-07 17:52:40.000000000 +0100
+++ MigrationTools-47-minmax-ugid/migrate_passwd.pl	2007-11-07 17:52:03.000000000 +0100
@@ -42,6 +42,41 @@
 $PROGRAM = "migrate_passwd.pl";
 $NAMINGCONTEXT = &getsuffix($PROGRAM);
 
+if ($#ARGV < 0) {
+	print STDERR "Usage: $PROGRAM [--minuid N] [--maxuid M] [--mingid N] [--maxgid M] infile [outfile]\n";
+	exit 1;
+}
+
+if ( defined($IGNORE_UID_BELOW) ) {
+	$minuid = $IGNORE_UID_BELOW;
+}
+if ( defined($IGNORE_UID_ABOVE) ) {
+	$maxuid = $IGNORE_UID_ABOVE;
+}
+if ( defined($IGNORE_GID_BELOW) ) {
+	$mingid = $IGNORE_GID_BELOW;
+}
+if ( defined($IGNORE_GID_ABOVE) ) {
+	$maxgid = $IGNORE_GID_ABOVE;
+}
+while ($ARGV[0] =~ /^--.*/) {
+	if ($ARGV[0] eq "--minuid") {
+		$minuid = $ARGV[1];
+		shift ; shift;
+	} elsif ($ARGV[0] eq "--maxuid") {
+		$maxuid = $ARGV[1];
+		shift ; shift;
+	} elsif ($ARGV[0] eq "--mingid") {
+		$mingid = $ARGV[1];
+		shift ; shift;
+	} elsif ($ARGV[0] eq "--maxgid") {
+		$maxgid = $ARGV[1];
+		shift ; shift;
+	} else {
+		shift;
+	}
+}
+
 &parse_args();
 &read_shadow_file();
 &open_files();
@@ -76,6 +93,10 @@
 	s/å/ae/g;
 
 	local($user, $pwd, $uid, $gid, $gecos, $homedir, $shell) = split(/:/);
+	next if (defined($minuid) and ($uid < $minuid));
+	next if (defined($maxuid) and ($uid > $maxuid));
+	next if (defined($mingid) and ($gid < $mingid));
+	next if (defined($maxgid) and ($gid > $maxgid));
 	
 	if ($use_stdout) {
 		&dump_user(STDOUT, $user, $pwd, $uid, $gid, $gecos, $homedir, $shell);