Easy switching network settings (home & office)

You can easily switch your network settings using the netsh command, instead of installing a lot of unnecessary software. Here are two examples, one for dhcp settings, and one for a static address. You can put it into a .bat file:

netsh interface ip set address "Net" source=dhcp

netsh interface ip set address "Net" static 192.168.0.xx 255.255.255.0 192.168.0.1 1

192.168.0.xx is your ip address, followed by the netmask and gateway. The last 1 is the metric. Optionally you can adjust your DNS values as well using set DNS instead of set address. This command helped me switching easily between my home network settings using dhcp and my office where there is a static address.

SSH login without password

If you want to make a bakup script like the one I showed you yesterday, you may need to set your machines to login remotely without asking for a password everytime. This is done by sharing between them the public rsa keys generated by the openssh server.

Login as the user you will use for the transfer script and run:

ssh-keygen -t rsa

Answer the questions but do not enter a password because otherwise you will still need to to pass it when the script runs. You should then have two new files in ~/.ssh, id_rsa and id_rsa.pub. Open id_rsa.pub with your favorite editor and copy everything (there is only one line actually) into the ~/.ssh/authorized_keys on the second machine (the one in which you need to copy).

Now try to login and if everything was set properly it won’t ask you for a a password anymore.

Simple script to backup virtual machines in linux

Currently I am using a small VMWare Server hosting 4 virtual machines, and i found my self in the position of backing them up. But the virtual machines need to be stopped before you can copy them somewhere else. Using the getstate() output of the vmware-cmd you can find the state of each virtual machine. using the following script you can set a cron job to backup your vitual machine:

#!/bin/sh
PATH="/srv/vmware-server/Contabilitate/Windows XP Professional.vmx"
CMD=$(vmware-cmd "$PATH" getstate)

case $CMD in
"getstate() = on")
vmware-cmd "$PATH" suspend
rsync -avz --stats --progress -e ssh /srv/vmware-server/Contabilitate root@192.168.0.3:/mnt/bak/04
rsync -avz --stats --progress -e ssh /srv/vmware-server/Contabilitate root@192.168.0.9:/var/bak/04
vmware-cmd "$PATH" start
;;
*)
esac