SSH Private Key Login

1. How to Generate Key File

sudo ssh-keygen -t rsa -b 4096 ;

cd /root/.ssh/; 

cat id_rsa.pub >> authorized_keys ;

chmod 600 authorized_keys && chmod 700 ~/.ssh ;

ls -ld ;
cat /etc/ssh/sshd_config ;

vim /etc/ssh/sshd_config ;

systemctl restart sshd.service ;

2. RSA to PPK or Vice Versa (e.g.: in homebrew )

brew install putty ;

puttygen id_rsa -o id_rsa.ppk;

puttygen id_rsa.ppk -O private-openssh -o id_rsa.pem ;

3. If system reminds “permissions *** for ***are too open”, then change it as below (Note: please modify the file path as your own) :

chmod 600 ~/Users/test/id_rsa ;

4. If system reminds “The authenticity of host ‘[8.8.8.8]:12345 ([8.8.8.8]:12345)’ can’t be established.” or ” ECDSA key fingerprint is SHA256: **********.”, just try as below:

4.1

ssh-add -l ; 

4.2 if it shows “The agent has no identities.”, then try as below (Note: please modify the file path as your own) :

ssh-add ~/Users/test/id_rsa ;

It will show “Identity added: ~/Users/test/id_rsa ([email protected])