diff --git a/ddos-mitigator.sh b/ddos-mitigator.sh
index a5b4b80..abfdf31 100755
--- a/ddos-mitigator.sh
+++ b/ddos-mitigator.sh
@@ -256,10 +256,10 @@ function parse_command_line_args() {
 			'')
 				autopilot=1
 				;;
-			*[!0-9]*)
-				echo "Invalid argument for parameter 'auto': '${2}'. Invoke with --help for help." >&2
-				exit 1
-				;;
+				#			*[!0-9]*)
+				#				echo "Invalid argument for parameter 'auto': '${2}'. Invoke with --help for help." >&2
+				#				exit 1
+				#				;;
 			*)
 				autopilot="$2"
 				;;
@@ -268,10 +268,10 @@ function parse_command_line_args() {
 			;;
 		'-c' | '--country')
 			IFS=',' read -ra bancountries <<<"${2}"
-			if [[ -z ${bancountries[@]// /} ]]; then
-				echo "Invalid argument for parameter 'country': '${2}'. Invoke with --help for help." >&2
-				exit 1
-			fi
+			#			if [[ -z ${bancountries[@]// /} ]]; then
+			#				echo "Invalid argument for parameter 'country': '${2}'. Invoke with --help for help." >&2
+			#				exit 1
+			#			fi
 			shift
 			;;
 		'-d' | '--database')
@@ -284,10 +284,6 @@ function parse_command_line_args() {
 			;;
 		'-f' | '--config-file')
 			configfile="${2}"
-			if [[ ! -f "${configfile}" || ! -r "${configfile}" ]]; then
-				echo "Can not read configuration file '${2}'. Invoke with --help for help." >&2
-				exit 1
-			fi
 			shift
 			;;
 		'-j' | '--jail')
@@ -296,21 +292,20 @@ function parse_command_line_args() {
 			;;
 		'-n' | '--netmask')
 			case "${2}" in
-			'1' | '8')
+			'1')
 				netmask=8
 				;;
-			'2' | '16')
+			'2')
 				netmask=16
 				;;
-			'3' | '24')
+			'3')
 				netmask=24
 				;;
-			'4' | '32')
+			'4')
 				netmask=32
 				;;
 			*)
-				echo "Invalid argument for parameter 'netmask': '${2}'. Invoke with --help for help." >&2
-				exit 1
+				netmask="${2}"
 				;;
 			esac
 			shift
@@ -337,21 +332,57 @@ function parse_command_line_args() {
 
 	# If the config file option is set, parse the config file.
 	if [[ ! -z ${configfile+x} ]]; then
+		if [[ ! -f "${configfile}" || ! -r "${configfile}" ]]; then
+			echo "Can not read configuration file '${2}'. Invoke with --help for help." >&2
+			exit 1
+		fi
+
 		parse_config_file
 	fi
 
+	# Here, we set the default values for all options that have not been set yet.
+	set_default_values
+}
+
+function validate_parameter_values() {
+	# Autopilot
+	case "${autopilot}" in
+	*[!0-9]*)
+		echo "Invalid value argument for parameter 'auto' / 'AUTOPILOT': '${autopilot}'." >&2
+		echo "Invoke with --help for help." >&2
+		exit 1
+		;;
+	esac
+
+	# Countries
+	if [[ -z ${bancountries[@]// /} ]]; then
+		echo "Invalid argument for parameter 'country' / 'COUNTRIES': '${bancountries[*]}'." >&2
+		echo "Invoke with --help for help." >&2
+		exit 1
+	fi
+
+	# Netmask
+	case "${netmask}" in
+	'8' | '16' | '24' | '32')
+		# Everything OK.
+		;;
+	*)
+		echo "Invalid argument for parameter 'netmask': '${2}'." >&2
+		echo "Invoke with --help for help." >&2
+		exit 1
+		;;
+	esac
+
+	# GeoIP-Database
 	if [[ -z "${database}" ]]; then
 		echo "No GeoIP database specified. Invoke with --help for more information." >&2
 		exit 1
 	fi
 
-	if [[ ! -r "${database}" ]]; then
+	if [[ ! -f "${database}" || ! -r "${database}" ]]; then
 		echo "Database '${database}' is not accessible." >&2
 		exit 1
 	fi
-
-	# Here, we set the default values for all options that have not been set yet.
-	set_default_values
 }
 
 ################################################################################
@@ -512,6 +543,7 @@ database=
 port=
 
 parse_command_line_args "$@"
+validate_parameter_values
 
 check_dependencies
 dependencies_ok=$?