Massimo's Blog

Do you need to know hostname, service tag, warranty expiry date of a remote dell server?

Try this quick hack:

echo "Hostname, Model, ServiceTag, Expiry Date" ; ssh -l root yourserver "export HW=\"\$(dmidecode | grep -i edge | awk -F':' '{ print \$2 }')\" ; export SN=\"\$(dmidecode | grep -i 'serial number' | head -n 1 | awk -F':' '{ print \$2 }')\" ; export EXP=\"\$(wget -q -O - \"http://support.dell.com/support/DPP/Index.aspx?c=us&cs=555&l=en&s=biz&ServiceTag=\$SN\" | grep --col 'Days Left' | perl -pe 's/.+?(\d+\/\d+\/\d+).+?(\d+\/\d+\/\d+).+/\$2/g')\"; echo \"\$HOSTNAME, \$HW, \$SN, \$EXP\""

which will print something like:

Hostname, Model, ServiceTag, Expiry Date
yourserver,  PowerEdge 2950,  ABCDEFG, 11/23/2011

This will try to explain how to use the ssh agent to forward your private key authentication on every box you connect.

Set this as your user crontab:


mmongardini@massimo-nb:~$ crontab -l


# m h  dom mon dow   command


@reboot ssh-agent -s | grep -v echo > $HOME/.ssh-agent

Set some useful aliases:

alias keyon="unset SSH_ASKPASS ; ssh-add -t 57600"

alias keyoff='ssh-add -D'

alias keylist='ssh-add -l'

Now run "keyon" and put your passphrase.

For now on your passphrase is loaded in your ssh-agent and is forwarded on each ssh connection.

Note: if the ssh client is not set to do agent_forwarding, use the -A option on every connection.

If you want to work in collaboration with someone remotely or for training purposes, you can use the "screen" multiuser functionality.

I generally use screen to run things where I don't want to destroy my thread if I lose my session.

Screen crash course:

By typing:
$ screen
No you will probably not notice any difference, but try and run something (eg. top) and leave the shell with "Ctrl-a d" you can then resume it with "screen -r".

Screen Multiuser:

Once entered in screen, if you type "Ctrl-a:multiuser". Someone loggin in using the same user as the one that started the screen session can see and interact with the session by typing "screen -x".

For security purposes I would suggest to create a shared login and give the right sudo rights for the session, and where possible to use ssh public keys in place of passwords.

Enjoy

today after a nice run I did my first swim in the Brighton sea with some of my colleagues... quite chilly but really nice!

My beloved gentoo box had a fever, but luckily I re-applied some "paracetamol" heath sink paste and the temperature went down!

My ganglia stats:

We did it, despite the weather!

The day before and during the morning it was so sunny that we thought, "came on, let's have a barbecue!".

But I guess that the actual ritual of lighting the coal and preparing the meat created a low pressure over our heads...

Oh well... we didn't give up and actually we enjoyed what we've cooked...

Volete impressionare gli amici, provate mplayer per mostrare il video della webcam con le librerie asciiart.

AsciiArt Webcam

Have you ever wished to connect directly to an host that is inside a natted network and you don't like to hop through hosts maybe even being able to do an scp directly to that host or an ssh -X? If your answer is yes and setting a vpn it's an overkilling task at the moment, you could benefit from ssh ProxyCommand!