ssh-keygen
-B -- show the bubblebabble digest of key
-C -- provide new comment
-D -- download key stored in smartcard reader
-N -- provide new passphrase
-P -- provide old passphrase
-U -- upload key to smartcard reader
-b -- specify number of bits in key
-c -- change comment in private and public key files
-e -- export key to SECSH file format
-f -- key file
-i -- import key to OpenSSH format
-l -- show fingerprint of key file
-p -- change passphrase of private key file
-q -- silence ssh-keygen
-t -- specify the type of the key to create
-y -- get public key from private key

-t 可以使用dsa ecdsa rsa rsa1

ssh-keygen -t rsa -b 2048 -C "youremail@example.com"

这个东西到时候会问你存在哪儿。生成的结果就是一对公私钥。