How to use ssh to log in without a password.
Problem:
Today I needed to mount a drive on a remote Linux server from within a Perl script. To do this, I should be able to call ssh to login without specifying the password.
Let's say, we want to connect as; user a on Host A to user b on Host B.
Here are the steps for doing this:
- First log in on A as user a and generate a pair of authentication keys. Select the default options while doing this (just hit enter.).
a@A:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory '/home/a/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
38:db:f0:80:aa:0f:dd:39:bc:9d:b7:23:a9:0f:be:1a a@A
2. Now, the private and public keys are created under the /home/a/ssh folder.
Now, create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine)
a@A:~> ssh b@B mkdir -p .ssh
b@B's password:
3. Append a's new public key to b@B:.ssh/authorized_keys and
enter b's password.
a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password:
After the third step, you should be able to login with ssh without entering password. The following command should not prompt for a password.
ssh b@B
If you still have to provide a password, try this:
- Change the permissions of .ssh to 700
