01 Apr 2017

Password Less SSH

# generate the private and public rsa key
ssh-keygen -t rsa -f test
# it will generate test(private key) and test.pub(public key) in ~/.ssh folder
# if folder not there, you may need to create it, assign 700 permission
# for windows, it will be in C:\Users\username\.ssh folder

# copy the public key to target server, you will ask for password first time
ssh-copy-id -i test.pub username@host
# replace username, host, pem name with your situation
# alternative way1: cat ~/.ssh/test.pub | ssh username@host 'cat >> .ssh/authorized_keys'
# alternative way2: manully create authorized_key and paste the test.pub content

# check the key permisson in both your machine and target server, otherwise it not work!
# .ssh folder: 700 (drwx------)
# test (private key): 600 (-rw-------)
# authorized_keys (public key): 644 (-rw-r--r--)

# after all those done, you can directly connect without password
ssh username@host

not-marco@rinzwind-desktop:~$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/home/not-marco/.ssh/id_rsa): 
Created directory '/home/not-marco/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/not-marco/.ssh/id_rsa.
Your public key has been saved in /home/not-marco/.ssh/id_rsa.pub.
The key fingerprint is:
b1:25:04:21:1a:38:73:38:3c:e9:e4:5b:81:e9:ac:0f not-marco@rinzwind-desktop
The key's randomart image is:
+--[ RSA 2048]----+
|.o= . oo.        |
|*B.+ . .         |
|*=o .   o .      |
| = .     =       |
|. o     S        |
|E.               |
| o               |
|  .              |
|                 |
+-----------------+
not-marco@rinzwind-desktop:~$ ssh-copy-id not-marco@127.0.0.1
not-marco@127.0.0.1's password: 
Now try logging into the machine, with "ssh 'not-marco@127.0.0.1'", and check in:

  ~/.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

# generate private key and public key in your local
ssh-keygen -t rsa -f awsnode
# login into ec2 node
# append the public key to aws ec2 node
vi ~/.ssh/authorized_keys
# now in authorized_keys will have two public key, one from Amazon, one from your
# you're able to connect by your own key
ssh -i ~/.ssh/awsnode username@ec2host