HOWTO: Speed up SSH login

[Jacky_J]

If you execute the command:

ssh username@hostname

and it takes a good 10-15 seconds to prompt you with a login/password, and you don't want it to take 10-15 seconds, then you've come to the right place.

You can blame IPv6 for this. Execute:

ssh -4 username@hostname

Note the -4 argument. This forces ssh to use only IPv4. If this doesn't speed it up, then you're probably out of luck.

Now, if you don't want to type -4 all the time (or are using CVS with ssh), edit your ssh_config file like so:

sudo gedit /etc/ssh/ssh_config

add the line

AddressFamily inet

Now you're set.

[Jeconais]

Works as advertised, thanks, very useful tip

[DarthMandeep]

Such a simple thing, yet it makes ssh so much nicer.

Thanks!

[majikstreet]

Thanks! Much faster... If only I could figure out a way for SSH to remember my passphrase for my ssh key.............

-m

[riggsd]

Thanks! Much faster... If only I could figure out a way for SSH to remember my passphrase for my ssh key.............

riggs@ubuntu:~ $ apt-cache show keychain
Package: keychain
Priority: optional
Section: universe/net
Installed-Size: 136
Maintainer: Cesar Mendoza <mendoza@debian.org>
Architecture: all
Version: 2.5.5-3ubuntu2
Depends: debconf (>= 1.2.0), openssh-client | ssh-client, grep (>= 2.4.2-1)
Filename: pool/universe/k/keychain/keychain_2.5.5-3ubuntu2_all.deb
Size: 33100
MD5sum: 37e60562c707fe032028fd3280bff756
Description: key manager for OpenSSH
 Keychain is an OpenSSH key manager, typically run from ~/.bash_profile. When
 keychain is run, it checks for a running ssh-agent, otherwise it starts one.
 It saves the ssh-agent environment variables to ~/.keychain/\-sh,
 so that subsequent logins and non-interactive shells such as cron jobs can
 source the file and make passwordless ssh connections.  In addition, when
 keychain runs, it verifies that the key files specified on the command-line
 are known to ssh-agent, otherwise it loads them, prompting you for a password
 if necessary.
Bugs: mailto:ubuntu-users@lists.ubuntu.com
Origin: Ubuntu

[majikstreet]

and I use it how?

[Jacky_J]

This is how I did it:

Basically, you need these files on your remote host:
~/.ssh/id_rsa
~/.ssh/id_rsa.pub
~/.ssh/authorized_keys

Then, on your local, you should have a copy of id_rsa
~/.ssh/id_rsa

If you don't know how to make those files, ssh to your remote host and execute

ssh-keygen -t rsa

enter in your passphrase, then do

cp .ssh/id_rsa.pub .ssh/authorized_keys

Then you need to copy id_rsa into your local .ssh directory (use scp or sftp)

after you have all the necessary files, execute

ssh-add

ssh-add should detect that you have a id_rsa file and asks for your passphrase. After you do this, you should be able to ssh without a password.
However, you need to do this everytime you boot your computer.

Ubuntu is nice because it has an ssh-agent ID ready to go, so you don't need to mess around with keychain.

[majikstreet]

ahh.. is there any way to put the password in the command?

[jdong]

It's gonna be more secure for you to just leave the passphrase blank. Typing in a password as a part of a command is typically a bad idea. Not only is it displayed to any user doing a 'ps aux', but it also tends to get logged in ~/.bash_history, which by default is world-readable (I change that on all my workstations).

The downside is that if anyone manages to steal your ~/.ssh directory (usually requires physical access), they have full password-free access to any systems you use non-passphrased authentication to, until you realize what happened and remove the key's entry from authorized_keys on the server's end.

[majikstreet]

That sucks..... I guess I'll just type in the password