# Page Not Found The URL `di-17-zhang-fang-huo-qiang/di-17.5-jie-fail2ban-pei-zhi-ji-yu-ipfw-pf-yu-ipf` does not exist. This page may have been moved, renamed, or deleted. ## Suggested Pages You may be looking for one of the following: - [18.5 Fail2Ban（基于 IPFW、PF 与 IPF）](https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.5-jie-fail2ban-pei-zhi-ji-yu-ipfw-pf-yu-ipf.md) - [18.1 防火墙概论](https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.1-jie-fang-huo-qiang-gai-shu.md) - [18.4 ipfirewall（IPFW）](https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.4-jie-ipfirewall-ipfw.md) - [18.3 IPFilter（IPF）](https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.3-jie-ipfilter-ipf.md) - [18.2 Packet Filter（PF）](https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.2-jie-packet-filter-pf.md) ## How to find the correct page If the exact page cannot be found, you can still retrieve the information using the documentation query interface. ### Option 1 — Ask a question (recommended) Perform an HTTP GET request on the documentation index with the `ask` parameter: ``` GET https://book.bsdcn.org/di-18-zhang-fang-huo-qiang/di-18.5-jie-fail2ban-pei-zhi-ji-yu-ipfw-pf-yu-ipf.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. ### Option 2 — Browse the documentation index Full index: https://book.bsdcn.org/sitemap.md Use this to discover valid page paths or navigate the documentation structure. ### Option 3 — Retrieve the full documentation corpus Full export: https://book.bsdcn.org/llms-full.txt Use this to access all content at once and perform your own parsing or retrieval. It will be more expensive. ## Tips for requesting documentation Prefer `.md` URLs for structured content, append `.md` to URLs (e.g., `/di-18-zhang-fang-huo-qiang/di-18.5-jie-fail2ban-pei-zhi-ji-yu-ipfw-pf-yu-ipf.md`). You may also use `Accept: text/markdown` header for content negotiation.