openssl genrsa -out private_key.pem 1024
ssh-keygen -t rsa -C zzf073@163.com
ssl是安全会话协商机制；
ssh是安全访问机制；
SSH是一个独立的安全会话应用
ssl是https协议的一部分。
ssl是一个库，ssh是一个独立的应用。
ssl独立以后，加上鉴权和复用机制以后就是ssh。
SSH 为建立在应用层基础上的安全协议。
SSH是由客户端和服务端的软件组成的
This isn't a reasonable comparison to make. SSL is a general method for protecting data transported over a network, whereas SSH is a network application for logging in and sharing data with a remote computer.
SSL SSH
+-------------+ +-----------------+
| Nothing | | RFC4254 | Connection multiplexing
+-------------+ +-----------------+
| Nothing | | RFC4252 | User authentication
+-------------+ +-----------------+
| RFC5246 | | RFC4253 | Encrypted data transport
+-------------+ +-----------------+
They differ on the things which are around the tunnel. SSL traditionally uses X.509 certificates for announcing server and client public keys; SSH has its own format. Also, SSH comes with a set of protocols for what goes inside the tunnel (multiplexing several transfers, performing password-based authentication within the tunnel, terminal management...) while there is no such thing in SSL, or, more accurately, when such things are used in SSL they are not considered to be part of SSL (for instance, when doing password-based HTTP authentication in a SSL tunnel, we say that it is part of "HTTPS", but it really works in a way similar to what happens with SSH).
https://security.stackexchange.com/questions/1599/what-is-the-difference-between-ssl-vs-ssh-which-is-more-secure
SSH 只是加密的shell，最初是用来替代telnet的。通过port forward，也可以让其他协议通过ssh的隧道而起到加密的效果。
OpenSSL 一个C语言函数库，是对SSL协议的实现。
openssl 中也有个叫做 openssl 的工具，是 openssl 中的库的命令行接口。
OpenSSH 是对SSH协议的实现。
openssh依赖于openssl，没有openssl的话openssh就编译不过去，也运行不了。
https://blog.csdn.net/whatday/article/details/89204543