blog.sudosu.net » Ubuntu

Seamless SSH

schof — Mon, 09 Jun 2008 18:59:10 +0000

I’m transitioning my daily work desktop from OS X Leopard to Kubuntu Hardy. (I’ll be writing more about that in the future.) My job is split between managing people and doing development and system administration for a bunch of Ubuntu boxes, so running the same platform that I’m administering makes a lot of sense. I DO miss some of the fit-and-finish of OS X, though, and I haven’t completely transitioned over to Linux for everything.

Ssh-agent is a great program that lets you add the password to your SSH private key to memory, and then you don’t need to type in the ssh key passphrase every time. The basic usage is that you start BASH as a child of ssh-agent, and then use a program called ssh-add to prompt you for the password and store it in memory.

On OS X, there’s a GREAT program called SSHKeychain that handles this, storing the password in your OS X keychain, so it’s really seemless.

On Linux, you need to type in “ssh-add” manually every time you want to store the key, and after that your SSH sessions will be seamless.

However, I’m always forgetting to do that, and thus getting prompted for the password. Too many seams. I added the following code snippet to the end of my .bashrc file, and thus, every time I open a bash shell, it checks whether ssh-agent has any keys in memory. If it does, the shell starts as normal. If ssh-agent doesn’t have any keys in memory, it prompts you for the password. Simple, and as seamless as I can make it.

## Add key to ssh-add if it has not been added.

ssh-add -l &> /dev/null
SSHADDRESULT=$?
if [ "$SSHADDRESULT" -ne "0" ]; then
ssh-add
fi

UPDATE 2008-07-02: Here’s a much more succinct way of writing that:

ssh-add -l &>/dev/null || ssh-add

Terminally Incoherent’s “Linux Fuckup Of The Day” — Using Single-User Mode To Recover

schof — Mon, 25 Jun 2007 19:34:45 +0000

From Terminally Incoherent:

Yep. I just removed myself from all the groups except for vboxusers. Brilliant! I absolutely hate when I do stupid shit like that. It’s not like this was hard to fix – I just didn’t remember of the top of my head what groups I was supposed to belong to. Of course since I was no longer part of the sudo and admin groups I could no longer sudo. Luckily enough, back in the day I decided to enable the root password. So I was able to su to become root, and then usermod myself to admin, and bunch of other groups I needed like audio, video, tty, lp and etc… I wonder what would happen if I did this on a default Ubuntu box without root account. I wonder if I would be able to recover from this that easily.

The short answer is “Yes, you would.” Single User Mode is your friend.

At bootup, hit ESC to get into the Grub menu, and select recovery mode. If you haven’t entered a root password, recovery mode will dump you to the console as root. If you HAVE defined a root password, recovery mode will dump to a login prompt, where you’ll have to enter the password.

Resolving a Very Uninformative Debootstrap Error Message

schof — Mon, 22 May 2006 20:02:52 +0000

So I’m trying to do an install with debootstrap onto a virgin partition. From my custom Ubuntu-based distribution. And I get the following error message:

E: Couldn't find these debs: 33024830

The error code itself is not Googleable, because it apparently changes for each install. (I got several different codes during the course of my troubleshooting.) Google got me here, where I learned that the –resolve-deps option was the secret. Appears to be working — at least, I’m much farther along in the process without failing.