idimmu . net

A web based memory replacement service.

Delete Linux MBR  July 29, 2010

Posted by idimmu in linux.
We run a build system using PXE and Puppet which lets us reliably and quickly set up production and development environments on our servers and maintain their consistency.

Every now and again we need to wipe the MBR of a Linux box in order to reboot it so it can PXE boot and reinstall itself. I like to use this command:

dd if=/dev/zero of=/dev/sda bs=446 count=1

which fills up the start of the disk with 0s, a simple reboot will then kick the box and start the PXE cycle!

Canon EOS Utility On A Mac Without A CD April 16, 2010

Posted by idimmu in photography.
Canon have a fantastic little app, which works on both Windows and Mac, called EOS Utility, which among other things allows you to do time lapse photography!

I lost my CD ages ago, because you know ... everyone knows that all responsible companies let you download support tools from their website ..

Unfortunately no one informed Canon of this amazing new way of thinking, and they only let you download an update for the EOS Utility application, which throws a massive hissy fit if you try to install it on a machine that doesn't already have it installed!

After a lot of Googling (that's now a verb .. get in line behind Hoover!) I found this awesome site :

Cracking Canons EOS Utility For Mac at the Hacker Blog!

With just a few mouse clicks you can tweak the Mac EOS Utility updater to act as an installer!

Thanks Hacker Blog!!

Slow SSH and SCP connections on Ubuntu January 23, 2010

Posted by idimmu in linux.
My home Ubuntu Jaunty installation often takes a good 40-60 seconds to connect to using SSH, none of the other servers I maintain have this same problem, they're pretty much instantaneous, and today, on a Friday evening at 1am this irked me enough to fix it!

The first step is of course to make the SSH connection with debug output on.


Chill:~ idimmu$ ssh -v cordy
OpenSSH_5.2p1, OpenSSL 0.9.7l 28 Sep 2006
debug1: Reading configuration data /Users/idimmu/.ssh/config
debug1: Reading configuration data /etc/ssh_config
debug1: Connecting to cordy [192.168.0.10] port 22.
debug1: Connection established.
debug1: identity file /Users/idimmu/.ssh/identity type -1
debug1: identity file /Users/idimmu/.ssh/id_rsa type -1
debug1: identity file /Users/idimmu/.ssh/id_dsa type 2
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-5ubuntu1
debug1: match: OpenSSH_5.1p1 Debian-5ubuntu1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.2
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'cordy' is known and matches the RSA host key.
debug1: Found key in /Users/idimmu/.ssh/known_hosts:7
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received

< 30 - 40 second pause occurs here >

debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/idimmu/.ssh/identity
debug1: Trying private key: /Users/idimmu/.ssh/id_rsa
debug1: Offering public key: /Users/idimmu/.ssh/id_dsa
debug1: Server accepts key: pkalg ssh-dss blen 433
debug1: read PEM private key done: type DSA
debug1: Authentication succeeded (publickey).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: Requesting authentication agent forwarding.
Linux Cordy 2.6.28-15-generic #49-Ubuntu SMP Tue Aug 18 18:40:08 UTC 2009 i686
Last login: Sat Jan 23 01:22:08 2010 from chill.local
idimmu@Cordy:~$


A quick Google for SSH2_MSG_SERVICE_ACCEPT and a read of man sshd_config gave me:


UseDNS Specifies whether sshd(8) should look up the remote host name and check that the resolved host name for the remote IP address maps back to the very same IP address. The default is ``yes''.


So I simply added


UseDNS no


to the end of /etc/ssh/sshd_config and issued an sudo /etc/init.d/ssh reload and bamo, instant SSH access and I can sleep peacefully!

Proper use of grails:exec January 7, 2010

Posted by idimmu in grails.
Whilst trying to run mvn grails:exec with more complicated requests it kept erroring:


Chill:superted idimmu$ mvn grails:exec -Dcommand="jack-be-nimble net.idimmu User Profile"
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'grails'.
[INFO] ------------------------------------------------------------------------
[INFO] Building Unnamed - net.idimmu:gymlife:war:1.0-SNAPSHOT
[INFO] task-segment: [grails:exec] (aggregator-style)
[INFO] ------------------------------------------------------------------------
[INFO] [grails:exec]
[INFO] Using Grails 1.2.0
Running pre-compiled script
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Unable to start Grails

Embedded error: java.lang.reflect.InvocationTargetException
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 14 seconds
[INFO] Finished at: Thu Jan 07 22:49:41 GMT 2010
[INFO] Final Memory: 32M/81M
[INFO] ------------------------------------------------------------------------


After some playing about, I finally found the correct runes


Chill:superted idimmu$ mvn grails:exec -Dcommand="jack-be-nimble" -Dargs="net.idimmu User Profile"
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'grails'.
[INFO] ------------------------------------------------------------------------
[INFO] Building Unnamed - net.idimmu:superted:war:1.0-SNAPSHOT
[INFO] task-segment: [grails:exec] (aggregator-style)
[INFO] ------------------------------------------------------------------------
[INFO] [grails:exec]
[INFO] Using Grails 1.2.0
Running script /Users/idimmu/Documents/stsworkspace/superted/plugins/nimble-0.3-SNAPSHOT/scripts/JackBeNimble.groovy
Environment set to development
Using package net.idimmu to create custom classes
Setting up nimble with custom User domain class: User
Setting up nimble with custom Profile domain class: Profile
[echo] Jack be nimble
[echo] Jack be quick
[echo] Jack jump over
[echo] The candlestick.
[copy] Copying 1 file to /Users/idimmu/Documents/stsworkspace/superted/grails-app/conf
[copy] Copying 1 file to /Users/idimmu/Documents/stsworkspace/superted/grails-app/conf
[copy] Copying 1 file to /Users/idimmu/Documents/stsworkspace/superted/grails-app/conf
[mkdir] Created dir: /Users/idimmu/Documents/stsworkspace/superted/grails-app/domain/net/idimmu
[copy] Copying 15 files to /Users/idimmu/Documents/stsworkspace/superted/grails-app/views/templates/nimble
[mkdir] Created dir: /Users/idimmu/Documents/stsworkspace/superted/src/sass
[copy] Copying 1 file to /Users/idimmu/Documents/stsworkspace/superted/src/sass
[copy] Copying 1 file to /Users/idimmu/Documents/stsworkspace/superted/src/sass
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 16 seconds
[INFO] Finished at: Thu Jan 07 22:56:52 GMT 2010
[INFO] Final Memory: 41M/81M
[INFO] ------------------------------------------------------------------------

Woo hoo!

Latest release information is not available for plugin 'nimble', specify concrete release to install January 7, 2010

Posted by idimmu in grails.
Whilst trying to install the Nimble plugin for Grails using Maven I ran in to a spot of bother!


Chill:superted idimmu$ mvn grails:install-plugin -DpluginName=nimble
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'grails'.
[INFO] ------------------------------------------------------------------------
[INFO] Building Unnamed - idimmu.net:superted:war:1.0-SNAPSHOT
[INFO] task-segment: [grails:install-plugin] (aggregator-style)
[INFO] ------------------------------------------------------------------------
[INFO] [grails:install-plugin]
[INFO] Using Grails 1.2.0
Running pre-compiled script
Environment set to development
Reading remote plugin list ...
Reading remote plugin list ...
Latest release information is not available for plugin 'nimble', specify concrete release to install


An investigation in to the available plugins yielded


Chill:superted idimmu$ mvn grails:list-plugins
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'grails'.

<snip>

nimble <0.3-SNAPSHOT (?)> -- Nimble

<snip>


So a bit of reading and thinking and specifically talking to another Grails developer, I found the solution


Chill:superted idimmu$ mvn grails:install-plugin -DpluginName=nimble -DpluginVersion=0.3-SNAPSHOT
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'grails'.
[INFO] ------------------------------------------------------------------------
[INFO] Building Unnamed - idimmu.net:superted:war:1.0-SNAPSHOT
[INFO] task-segment: [grails:install-plugin] (aggregator-style)
[INFO] ------------------------------------------------------------------------
[INFO] [grails:install-plugin]
[INFO] Using Grails 1.2.0
Running pre-compiled script
Environment set to development
Reading remote plugin list ...
Reading remote plugin list ...
[get] Getting: http://plugins.grails.org/grails-nimble/tags/RELEASE_0_3-SNAPSHOT/grails-nimble-0.3-SNAPSHOT.zip
[get] To: /Users/idimmu/.grails/1.2.0/plugins/grails-nimble-0.3-SNAPSHOT.zip

<snip>