Every program wanting to access the internet will ask its host computer's Operating System to be given a unique port.

每个想要访问互联网的程序都会要求其主机的操作系统获得一个唯一的端口。

If an attacker installs malicious software – called malware – compromising the host computer's operating system, how can we be sure security programs don't have a backdoor that let attackers in?

如果攻击者安装了恶意软件（称为恶意软件）来破坏主机的操作系统，我们如何确保安全程序没有让攻击者进入的后门？