09 Jan 2008 SSH Without a Password

The following steps can be used to ssh from one system to another without specifying a password.
Notes:

The system from which the ssh session is started via the ssh command is the client.
The system that the ssh session connects to is the server.
These steps seem to work on systems running OpenSSH.
The steps assume that a DSA key is being used. To use a RSA key substitute ‘rsa’ for ‘dsa’.
The steps assume that you are using a Bourne-like shell (sh, ksh or bash)
You should consider the security risks before implementing this feature

Steps:

On the client run the following commands:
```
$ mkdir -p $HOME/.ssh
```
```
$ chmod 0700 $HOME/.ssh
```
```
$ ssh-keygen -t rsa -f $HOME/.ssh/id_rsa -P ''
```
This should result in two files, $HOME/.ssh/id_rsa (private key) and $HOME/.ssh/id_rsa.pub (public key).
Copy $HOME/.ssh/id_rsa.pub to the server.
On the server run the following commands:

$ cat id_rsa.pub >> $HOME/.ssh/authorized_keys2

$ chmod 0600 $HOME/.ssh/authorized_keys2

Depending on the version of OpenSSH the following commands may also be required:

$ cat id_rsa.pub >> $HOME/.ssh/authorized_keys
$ chmod 0600 $HOME/.ssh/authorized_keys

An alternative is to create a link from authorized_keys2 to authorized_keys:

$ cd $HOME/.ssh && ln -s authorized_keys2 authorized_keys

On the client test the results by ssh’ing to the server:
```
$ ssh -i $HOME/.ssh/id_rsa server
```
(Optional) Add the following $HOME/.ssh/config on the client:
```
Host server
IdentityFile ~/.ssh/id_rsa
```

This allows ssh access to the server without having to specify the path to the id_rsa file as an argument to ssh each time.

Tags: ssh

ramangill | 25 Sep 2009 17:12
Is it possible to eloborate further on steps 12, 13 and 14….I am confused about it.
bixit | 28 Sep 2009 11:16
Hi, I have fixed a typo in this post.
Thanks for the tip
paul | 26 Mar 2013 23:53
I think there’s typo here. It’s not ‘id_dsa’ instead it’s ‘id_rsa’ in several places.
- Hans-Henry Jakobsen | 05 Apr 2013 7:59
  Yes, you are right.
  I have fixed the typos, thanks :)