dropbear是轻量的sshd服务器，与OpenSSH相比，他更简洁，更小巧，运行起来占用的内存也更少。如果你的VPS只有128M内存，甚至 64M内存，而你又比较喜欢开多个ssh终端，或者开一些ssh账号给其他同学用的话，还是比较有必要的，因为，每一个普通用户登录，OpenSSH会开两个sshd进程，而dropbear只开一个进程，这样算起来，OpenSSH内存占用是dropbear的5-6倍。-dropbear sshd server is lightweight compared with OpenSSH, he is more concise, more compact, up and running takes up less memory. If your VPS only 128M of memory, and even 64M memory, and you prefer to open multiple ssh terminal, or the opening of a number of ssh account to other students with the words, it is quite necessary, because every ordinary user login, OpenSSH will open two sshd process, and dropbear open only a process, so you figure, OpenSSH memory footprint is dropbear 5-6 times.