Login without a password.

ssh-keygen

hmm... This is use to generate the private and public keys to authenticate ssh. Yesterday i had to use this command to generate a public key as per our network admins request. [You are wrong... he's a good one..! ;)] He told me that i don't need to type the password each and every time when i'm connecting to the GIT. [mm...  it's a version control system like SVN.]

Fortunately it light up a new idea. [yes... new for me.. :D] 

Ok.. These are the steps.

1) $> ssh-keygen -t rsa         : Generate private/public rsa keys.

         Enter file in which to save the key (/home/kumudu/.ssh/id_ras) : <return>

         Enter passphrase (empty for no passphrase):  <return>

         Enter same passphrase again:  <return>

         Your identification has been saved in /home/kumudu/.ssh/id_rsa.

         Your public key has been saved in /home/kumudu/.ssh/id_rsa.pub.

         The key fingerprint is:

         67:5b:54:e8:1f:eb:46:7a:00:3b:72:33:9a:cc:d3:32 kumudu@hmslp030

         The key's randomart image is:

         +--[ RSA 2048]----+

          |                          ..  |

          |                         ..   |

          |                        ..    |

          |                       ... .  |

          |                 S oo.. o |

          |                 .o*o. +  |

          |                o *.+ =   |

          |                   E . . +  |

          |                    +   o   |

         +-------------------+

Ok... Your public key is in /.ssh/id_rsa.pub file. 

2) $> ssh-add      :  This will add the generated keys to ssh. (If you miss this you will get a message like "Agent admitted failure to sign using the key." while connecting to the remote machine.  [I spend lot of time to find this...])

3) Copy that public key onto remote machines' .ssh/authorized_keys file. (mmm... normally this file doesn't exist. Just create a new file named "authorized_keys" in .ssh folder and copy the public key into it.)

4) Then make the file permission as follows. (Actually i don't know the exact reason for this. Without this permission ssh refuse to use the key)

       $> chmod 600 .ssh/authorized_keys

5) $> ssh <profile_name>@<remote_host>

hmmm... thats all.. I tested it on fedora machine and ubuntu machine. 

Advantages.

• If someone ask for login to your machine through ssh, simply ask him to send the rsa public key. Then add it to your autherized_keys file. [you don't need to expose your password]

• The other person don't need to remember your password. [yes.. yes... only the ip ;)]

• If you want to stop him just remove the key...