SSH

Passwordless Login

Unix, Linux, Mac OS X, and Cygwin

Users can set up SSH so that they have passwordless ssh access to DreamHost servers. (Please read 'Single Password Logon' for security concerns.)

On your home computer, you must generate an RSA private key:

ssh-keygen -t rsa

It will prompt you for three things, hit enter to accept the default on all three.

Next, you must copy your public key to DreamHost's server. Replace user and example.com with your username and domain name, respectively.

scp ~/.ssh/id_rsa.pub user@example.com:~/

Now you must ssh to your account (using your password):

ssh user@example.com

Now append the public key to your authorized keys file and delete the file you uploaded:

mkdir .ssh
cat id_rsa.pub >> .ssh/authorized_keys
rm id_rsa.pub

Now make sure permissions are set properly for all necessary files and directories:

chmod go-w ~
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

If everything is configured properly, you should be able to access your DreamHost account through SSH without a password now! For more information, see the man pages for ssh, ssh-keygen, and sshd.

SSH Speeds

Performance hit on SCP/SFTP transfers, below is a table of performance stats based upon ciphers.

aes128-ctr				
600.iso		600MB	30.0MB/s	0:20
600.iso		600MB	28.6MB/s	0:21
aes192-ctr				
600.iso		600MB	26.1MB/s	0:23
600.iso		600MB	25.0MB/s	0:24
aes256-ctr				
600.iso		600MB	24.0MB/s	0:25
600.iso		600MB	24.0MB/s	0:25
arcfour256				
600.iso		600MB	75.0MB/s	0:08
600.iso		600MB	85.7MB/s	0:07
arcfour128				
600.iso		600MB	85.7MB/s	0:07
600.iso		600MB	85.7MB/s	0:07
aes128-cbc				
600.iso		600MB	50.0MB/s	0:12
600.iso		600MB	46.2MB/s	0:13
3des-cbc				
600.iso		600MB	12.2MB/s	0:49
600.iso		600MB	12.0MB/s	0:50
blowfish-cbc				
600.iso		600MB	40.0MB/s	0:15
600.iso		600MB	42.9MB/s	0:14
cast128-cbc				
600.iso		600MB	27.3MB/s	0:22
600.iso		600MB	23.1MB/s	0:26
aes192-cbc				
600.iso		600MB	46.2MB/s	0:13
600.iso		600MB	42.9MB/s	0:14
aes256-cbc				
600.iso		600MB	40.0MB/s	0:15
600.iso		600MB	40.0MB/s	0:15
arcfour				
600.iso		600MB	85.7MB/s	0:07
600.iso		600MB	85.7MB/s	0:07

• Options

ssh -oCiphers='arcfour' user@host

scp -oCiphers='arcfour'

rsync -e'ssh -oCiphers=arcfour'