SSH auto login
Auto login in remote machine
Sometimes, we would like to automatically login to remote machine without keying the password. It can be done by generating public/private key and stores the keys in the remote machine.
Steps:
1) Open a terminal, and type the following line in the local machine:
~$ ssh-keygen -t rsa -b 2048
Output:
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/henry/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/henry/.ssh/id_rsa.
Your public key has been saved in /Users/henry/.ssh/id_rsa.pub.
The key fingerprint is: xxx
2) Then type the following to copy the keys in the remote machine
~$ ssh-copy-d user@server_ip
Output:
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/Users/userid/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
user@server_ip's password:
Key in the password
Number of key(s) added: 1
Now try logging into the machine, with: "ssh 'user@server_ip'"
and check to make sure that only the key(s) you wanted were added.
3) Now we can login to the remote machine without key in the password.
To automatically ask a remote machine to run a script
Let's say we would like to run the command "last > dump.txt" at remote machine "server_ip", type the following command:
~$ ssh user@server_ip "last > dump.txt"