GeekLad » Miscellaneous Geekery

Generate SSH Keys in Two Easy Steps

GeekLad — Tue, 21 Jul 2009 13:02:56 +0000

This post is probably as much for me as it is everyone else. I got sick of having to look up 3 or 4 different SSH keygen tutorials every time I needed to generate a private/public SSH key pair, so I thought I’d write up my own. Here’s how to make your own SSH keys at a shell prompt (i.e. Linux):

Run the following commands on the machine you will be logging into:

ssh-keygen chmod 700 ~/.ssh cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys2 chmod 600 ~/.ssh/authorized_keys2 rm ~/.ssh/id_rsa.pub
Note: You may need to replace authorized_keys2 with just authorized_keys.
Copy the id_rsa file to the client machine (the machine you will be logging in from) and run the following command:

ssh-add id_rsa

That’s all there is to it! Please be sure to keep the id_rsa file safe, and don’t ever share it with anyone unless you want them to log into the account. You should protect the private keyfile in the same manner you would protect any password.

You may get an error on the client machine that says Could not open a connection to your authentication agent. If you see this message, run the following command:
exec ssh-agent bash

That will start the ssh agent and allow you to connect to it so that you can add the new key.

Alternate Step 2 for Windows Clients

If your client is a Windows machine, you’re probably using PuTTY to connect to the host. If that is the case, step 2 will be different for you and you’ll want to use PuTTYgen to import the key.

Just launch PuTTYgen, click Conversions and then Import key.

Then click Save private key and you’re done!

Connecting to an SSH Host with PuTTY

You should be able to use the key to connect to the host from PuTTY. Just start up PuTTY, load your saved session or enter the host info, go to Connection > SSH > Auth and browse to the private key (.ppk file) you just saved.

Still Alive on Carillon

GeekLad — Wed, 28 Jan 2009 11:34:52 +0000

Yesterday my good Friend Bwana shared an article on Lifehacker about GrandCentral preparing for a new release. In his comment along with the shared item Bwana said,

Play the Portal Theme… Still Alive..

Of course, that prompted me to search YouTube for the song. I listened to it and I enjoyed it. I also checked out a few others including a live version of Still Alive performed by the writer, Johnathan Coulton.

After listening to the live version, I searched for Johnathan’s blog and started browsing around on it. I came across a post of Still Alive being played on the carillon. Check out the video. The carillon isn’t terribly impressive to watch, but it’s a cool video to listen to.

Laptop as a Wireless Router

GeekLad — Thu, 25 Sep 2008 21:24:33 +0000

You may some day come across the rare situation of temporarily needing an extra wireless router. I can’t really think of a good example, but I know that I encountered such a situation yesterday. I decided I would write up an article as it may prove useful to others that may find themselves in a similar situation some day.

I had a PC lying around that was still quite usable, but I only had one monitor. Eventually I decided it would be worthwhile to purchase a second monitor so that my wife could make use of the computer. We also decided we would put it into a separate room, so it would not be located adjacent to the other computer and Internet connection. In addition to the monitor, I also ordered a wireless router, wireless keyboard, and a wireless mouse to use with the machine.

Well, as it so happened, the monitor arrived in a separate shipment before the router and peripherals did. After I had nearly completed hooking everything up, my wife informed me that she wanted to get online with it to buy some music for her iPod. Of course, this PC was the home machine for the iPod. I really didn’t feel like moving everything back to the office, hook it all up so she could get online and get her music, then move it back to the permanent home. I then had a revelation and realized I could use my laptop as a wireless router.

Diagram for Laptop as a Router

Here are the basic requirements for using your laptop as a wireless router:

A laptop with a wireless network device as well as an ethernet device (duh!)
A wireless router that is hard-wired to your Internet connection
A hub or router for connecting to the laptop and other machines (alternatively, you could use a crossover cable)
At least two ethernet cables, one for the laptop and one for other machines

I was fortunate I had an old hub stashed away within the depths of my gadget closet and had plenty of unused ethernet cables lying around. Basically all you need to do is:

Connect the laptop to the hub via one of the ethernet cables
Connect the computer(s) to the hub via the other ethernet cable(s)

If you use a crossover cable instead of a hub, you would connect the ethernet port on the computer directly to the one on the laptop.

Connect the laptop to the wireless hub with the laptop’s wireless device (you are probably already doing this)
Set up Internet connection sharing on the laptop to share the wireless device

Network Connections Window

Internet Connection Sharing

If you are using Windows XP:

Launch the control panel
Go to your network connections
Right-click on the wireless device and go to properties
Click the Advanced tab
In the Internet Connection Sharing section, click the check box that says Allow other network users to connect through this computer’s Internet connection
Click OK

That’s all there is to it! This will also work fine with a Mac or Vista laptop. I don’t have either, so I’m not at liberty to provide step-by-step instructions and screen shots. The physical setup would be exactly the same. You would just have to take different steps to set up Internet connection sharing. Just be sure that you set it up to share the connection on the wireless device.