针对 VPS 运维安全，本文提供 Ubuntu/Debian 系统下 UFW (Uncomplicated Firewall) 的实操配置指南。涵盖设置默认拒绝策略、预防 SSH 锁定、开放 Web 常用端口以及规则的增删改查与重置，助你快速构建服务器的第一道安全屏障。

How code blocks look in Markdown using Expressive Code.

Read more about Markdown features in Fuwari

How code blocks look in Markdown using Expressive Code.

A simple example of a Markdown blog post.

This post demonstrates how to include embedded video in a blog post.