Đây là mặc định (đối với khả năng tương thích với RFC 2822). - Iso-8859-x: x là trong phạm vi từ 1 đến 9 cho các bộ phận khác nhau của tiêu chuẩn ISO-8859. Văn bản bao gồm các nhân vật ISO trong phạm vi 0 đến 255 (thập phân). Tất cả các bộ ký tự ISO-8859 ASCII dựa trên các ký tự ngôn ngữ quốc gia | Access control Encryption Authentication Integrity checking Perfect forward security Address concealment Session monitoring Application proxy Y Normally no Y user Y Normally no Y Y connection and data AAA servers y user N Y user N N N N An overall security solution can in most cases only be provided by a combination of the listed options. Your particular security requirements need to be specified in a security policy and should be for example enforced by using firewalls and validated by using security health checking tools and vulnerability scanners. Network security policy An organization s overall security policy must be determined according to security and business needs analysis and based on security best practices. Because a firewall relates to network security only a firewall has little value unless the overall security policy is properly defined. A network security policy defines those services that will be explicitly allowed or denied how these services will be used and the exceptions to these rules. Every rule in the network security policy should be implemented on a firewall remote access server RAS or both. Generally a firewall uses one of the following methods. Everything not specifically permitted is denied This approach blocks all traffic between two networks except for those services and applications that are permitted. Therefore each desired service and application is implemented one by one. No service or application that might be a potential hole on the firewall is permitted. This is the most secure method denying services and applications unless explicitly allowed by the administrator. However from the point of users it might be more restrictive and less convenient. Everything not specifically denied is permitted This approach allows all traffic between two networks except for those services and applications that are denied. Therefore each untrusted or potentially harmful service or application is denied one by one. Although this is a .
