请将以下文档总结为三句话，尽量保留关键信息。 Firewalling techniques are an essential part of cybersecurity, aimed at preventing unauthorized access to or from a private network. The most common firewall is the packet filter, which examines each packet and decides whether to forward it based on a set of rules. More sophisticated firewalls, like the stateful inspection firewall, can provide deeper packet inspection and better security, but they are more resource-intensive.
user
防火墙技术是网络安全的重要组成部分，主要用于防止未授权访问私有网络。最常见的防火墙类型是数据包过滤器，它根据一组规则检查每个数据包并决定是否转发。更高级的防火墙，如状态检测防火墙，能提供更深入的数据包检查和更好的安全性，但需要更多的资源。
assistant