Tuesday 1 April 2014

How To Do SSH Without Password On Ubuntu

1. ssh to server1

ssh myusername@server1
password:
ssh-keygen -t rsa

When you run this command you will be prompted to answer several questions. Just hit enter each time until you are returned to a prompt.

Generating public/private rsa key pair.

Enter file in which to save the key (/home/local/myusername/.ssh/id_rsa):

Created directory '/home/local/myusername/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/local/myusername/.ssh/id_rsa.
Your public key has been saved in /home/local/myusername/.ssh/id_rsa.pub.
The key fingerprint is:
15:68:47:67:0d:40:e1:7c:9a:1c:25:18:be:ab:f1:3a myusername@server1
The key's randomart image is:
+--[ RSA 2048]----+
|        .*Bo=o   |
|       .+o.*  .  |
|       ...= .    |
|         + =     |
|        S +      |
|         .       |
|      . .        |
|      E+         |
|      oo.        |
+-----------------+

Now you will need to copy the public key you just generated and save it somewhere, you will need it later. Also ensure when you copy the key that the text is all on one line, if there are line breaks in the text, it will cause problems later when you try and use the key.

cd .ssh
cat id_rsa.pub

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAyFS7YkakcjdyCDOKpE4RrBecRUWShgmwWnxhbVNHmDtJtK
PqdiLcsVG5PO94hv3A0QqlB1MX33vnP6HzPPS7L4Bq+5plSTyNHiDBIqmZqVVxRbRUKbP44BaA9RsW2ROu
8qdzmXRPupkyFBBOLa23RJJojBieFGygR2OwjS8cq0kpZh1I3c1fbU9I5j38baUK0naTBe2v7s/C8allnJ
hwkfds+Q9/kjaV55pMZIh+9jhoA8acCA6B55DYrgPSycW6fEyV/1PIER+a5lOXp1QCn0U+XFTb85dp5fW0
/rUnu0F9nBJFlo7Rvc1cMuSUiul/wvJ8tzlOhU8FUlHvHqoUUw== myusername@server1

2. ssh to server2

Now we will copy the public key from server1 to server2.

ssh myusername@server2
password:
mkdir .ssh
cd .ssh
vi authorized_keys
# paste the public key
chmod 600 authorized_keys

3. Test that your setup is working

ssh myusername@server1
password:
ssh myusername@server2
# you should not be prompted for a password

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