ssh private key

login server without password

1. generate key (on my own computer)

   ssh-genkey -t rsa -f rsa_name
   (have to change the name of key, otherwise it will override the old one)

2. put the public key to the server
   For example, the keys are called id_rsa_xx(private key) and id_rsa_xx.pub(public key)

   scp id_rsa_xx.pub server
   cd /server/.ssh
   cat id_rsa_xx.pub >> ~/.ssh/authorized_keys (if not, rename it to authorized_keys)

3. If there are multiple private keys in our own computer, modify ~/.ssh/config

   vim config

   Host servername
   User username
   IdentityFile ~/.ssh/id_rsa_xx

4. Make sure ~/.ssh dir and ~/.ssh/authorized_keys on the remote machine must be writable only by you ( ref ). 700 or 755, but not 775

It works now