(Hardware firewall is an important barrier to ensure the security of internal network. Its security and stability are directly related to the security of the entire internal network. At present, there are many kinds of firewalls in the market, and the quality and price are quite opaque. When asked about the price, it is often tens of thousands of yuan, or even 200000 yuan, but its internal quality and materials are difficult to agree. Tang Hua, the author of this article, doesn't stop at one thing. He just wants to build a 1U hardware firewall DIY! For more information, please read the article.)