Kirk Ismay

Just another WordPress hacker...

Repartition a Debian Digital Ocean Droplet

by

1. Create a Droplet

For this example, I made a small droplet running Debian 8.1 x64.  These instructions may work for older Debian versions, and might work for Ubuntu.  You may need to use some other method to boot a live environment than the Grml package I used.

https://www.digitalocean.com/community/tutorials/how-to-create-your-first-digitalocean-droplet-virtual-server

On first boot, you can see that we have a 20GB disk (/dev/vda) as a single Linux partition:

root@debian:~# fdisk -l /dev/vda
 Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
 Units: sectors of 1 * 512 = 512 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disklabel type: dos
 Disk identifier: 0x4e0e3620
Device     Boot Start      End  Sectors Size Id Type
/dev/vda1  *     2048 41935724 41933677  20G 83 Linux

2. Install GRML RescueBoot

It’s a two step process, first install the grml-rescueboot debian package, then download the grml iso to /boot/grml/ with wget:

root@debian:~# apt-get install grml-rescueboot
root@debian:~# wget http://download.grml.org/grml64-small_2014.11.iso
root@debian:~# update-grub
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.16.0-4-amd64
Found initrd image: /boot/initrd.img-3.16.0-4-amd64
Found Grml ISO image: /boot/grml/grml64-small_2014.11.iso
done

3. Boot from GRML

The default boot option mounts the vda device automatically, making it impossible to resize.  You need to go to the advanced options and set it to run from a RAM disk instead. Here’s the steps and a few screenshots to help:

  1. Type reboot or shutdown -r now on the terminal window and wait for the Grub menu
  2. Select the Grml Rescue Image Option from the Grub menu
  3. Select ‘advanced options’ from the Grml boot menu
  4. Select ‘copy Grml to RAM’ option

4. Repartition

  1. use resize2fs to shrink the existing filesystem: 
    root@grml ~ # fsck.ext4 -f /dev/vda1
root@grml ~ # resize2fs -M /dev/vda1
  2. use parted to shrink the partition and create a new LVM partition: 
    root@grml ~ # parted /dev/vda
(parted) resizepart 1 3G
(parted) mkpart primary 3001 100%
(parted) set 2 lvm on
(parted) quit
  3. Verify your work: 
    root@grml ~ # fdisk -l /dev/vda
  4. Reboot to Debian: 
    root@grml ~ # reboot
  5. Use LVM tools to create logical volumes: 
    root@debian:~# apt-get install lvm2
root@debian:~# pvcreate /dev/vda2
root@debian:~# vgcreate vg1 /dev/vda2
root@debian:~# lvcreate -L 5G -n home /dev/vg1
  6. Format and mount: 
    root@debian:~# mkfs.ext4 -L home /dev/vg1/home
root@debian:~# mount /dev/mapper/vg1-home /home
root@debian:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/vda1             2.7G  1.5G  1.1G  58% /
udev                   10M     0   10M   0% /dev
tmpfs                  99M  4.4M   95M   5% /run
tmpfs                 248M     0  248M   0% /dev/shm
tmpfs                 5.0M     0  5.0M   0% /run/lock
tmpfs                 248M     0  248M   0% /sys/fs/cgroup
/dev/mapper/vg1-home  4.8G   10M  4.6G   1% /home
/dev/mapper/vg1-tmp   976M  1.3M  908M   1% /tmp
  7. Add your new volumes to /etc/fstab: 
    # /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/vda1 during installation
UUID=22f7f3aa-4357-445b-b324-9b86ee23a508 /               ext4    errors=remount-ro 0       1
/dev/mapper/vg1-home  /home  ext4   defaults,nosuid,nodev   0    2
/dev/mapper/vg1-tmp   /tmp   ext4   defaults,nosuid,nodev   0    2

5. Enjoy!

Go forth and partition your system logically according to your every whim!

Review of Linux Malware Detect

by

Linux Malware Detect is an open source malware scanner designed to detect threats found in a shared web hosting environment. It’s signature based, sharing the same virus definition format as ClamAV. It will actually use clamscan, if available, as the scanning engine for increased performance. It can also clean up infected HTML or PHP files in some cases.  I’ve installed it on both a Debian Lenny server and a CentOS 5.7 system, with no difficulty.

Installation

Installing Linux Malware Detect:

$ cd /usr/src
$ wget http://www.rfxn.com/downloads/maldetect-current.tar.gz
$ tar zxvf maldetect-current.tar.gz
$ cd maldetect-1.4.1
$ sudo ./install.sh

First Scan

By default, maldet installs a cron job to /etc/cron.daily/.  This cron job will scan common web site directories each day for files created in the last 2 days.  It looks for the presence of installed hosting control panels and scans accordingly.  Review this file and ensure it will work in your environment.  It can also be set up to scan new files on demand through either inotify or modsecurity for Apache.

Since it only scans the most recent files, its a good idea to do a full scan by hand:

$ sudo /usr/local/maldetect/maldet -b -a /var/www/vhosts/

To follow the progress, watch the scan log like this:

$ sudo tail -f /usr/local/maldetect/event_log
Jul 19 10:38:38 www4 maldet(19848): {scan} launching scan of /var/www/vhosts/ to background, see /usr/local/maldetect/event_log for progress
Jul 19 10:38:39 www4 maldet(19848): {scan} signatures loaded: 9649 (7782 MD5 / 1867 HEX)
Jul 19 10:38:39 www4 maldet(19848): {scan} building file list for /var/www/vhosts/, this might take awhile...
Jul 19 10:39:07 www4 maldet(19848): {scan} file list completed, found 56291 files...
Jul 19 10:39:07 www4 maldet(19848): {scan} found ClamAV clamscan binary, using as scanner engine...
Jul 19 10:39:07 www4 maldet(19848): {scan} scan of /var/www/vhosts/ (56291 files) in progress...
Jul 19 10:39:32 www4 maldet(19848): {scan} scan completed on /var/www/vhosts/: files 56291, malware hits 0, cleaned hits 0
Jul 19 10:39:32 www4 maldet(19848): {scan} scan report saved, to view run: maldet --report 071912-1038.19848

Wrapping Up

Linux Malware Detect does what it says on the tin. It’s a valuable addition to a sysadmin’s toolbox if you’ve got any public facing linux web servers.

Installing a Debian Lenny DomU under a CentOS 5 Dom0

by

I spent some time recently trying to figure out how to go about installing Debian Lenny as a Xen domU (guest) virtual machine on a CentOS 5.5 dom0. I found Andy’s article on the process, but had trouble getting it to work. I also found another article by Tom on how to install Xen and libvirt on Debian Lenny.   If you skip down to the section “On to installing a virtual machine!”, we see how to install debian with the virt-install command.

Once this is done we can install our first virtual machine:

# virt-install \
--name=test-debian-install \
--ram=1024 \
--file-size=10 \
--nographics \
--paravirt \
--file=/var/lib/xen/images/test-debian-install.img \
--location=http://ftp.belnet.be/debian/dists/lenny/main/\
installer-i386

As it turns out, this command works out of the box on CentOS as well!  You do need to install the libvirt package first, of course, but after that it just works.  As a handy tip, the –location parameter can be set to your favorite debian mirror.  I used http://ftp.ca.debian.org/debian/dists/lenny/main/installer-i386/,  and that works just as well.

I prefer to use logical volumes instead of disk image files for my servers. Just create a new logical volume and change the –file parameter like this:

# lvcreate -L20G -n xenvm00 VolGroup00
# virt-install \
--name=test-debian-install2 \
--ram=1024 \
--file-size=10 \
--nographics \
--paravirt \
--file=/dev/VolGroup00/xenvm00 \
--location=http://ftp.ca.debian.org/debian/dists/lenny/main/\
installer-i386

Using the above instructions greatly simplifies the process of installing Debian Lenny as a Xen Guest under CentOS 5.5. Once the virt-install command completes, you will be presented with the standard Debian installer, and everything will proceed normally from there.

WordPress 2.7.1 Painless Upgrade

by

I had the evening free tonight, and decided to burn some time upgrading my blog to the latest version of WordPress. I checked out the handy upgrade instructions, and then went to work.  In less than 10 minutes, I was all done.

I host my blog on a Debian Linux server at work, and did the upgrade via ssh. To get started, I used the BackUp WordPress plugin to backup my files for safety’s sake, then I disabled all plugins as instructed.  I should mention that all of my plugins were up to date before the upgrade, which is probably a good idea to prevent compatibility issues before they start.

Once I was done that, I ran the following commands using ssh:

$ wget http://wordpress.org/latest.zip
$ unzip latest.zip
$ cd public_html
$ mv wp-includes wp-includes.old
$ mv wp-admin wp-admin.old
$ cp *.php .

$ rsync -Cav ../wordpress/wp-content/ wp-content/
WordPress 2.7.1 Dashboard Screenshot

WordPress 2.7.1 Dashboard Screenshot

With that done, I logged back in to my admin dashboard. WordPress prompted me to update the database, and I was greeted with the stylin’ new interface of WordPress 2.7.1.

Now I’ll have to find something else to do! 😉

Upgrading to Debian ‘Lenny’

by

Debian Lenny

Debian Lenny

Today I took the plunge and installed lenny on my home computer. Its a desktop computer / experimental server. The process was remarkably simple. I edited /etc/apt/sources.list, and replaced all instances of etch with lenny. Then I ran apt-get -yd dist-upgrade to download the packages first. At first I didn’t have enough room to download all 560MB worth of new packages, fortunately when I set it up this system I used LVM. I was able to add another couple gig’s to the partition, and the lvextend and resizext2fs commands worked perfectly to grow my root volume without unmounting it or rebooting.

Once that was done, it took about 4 hours to download all the packages, but once that was done, the rest was pretty painless. The only hitch was that I was using the fglrx driver (the non-free driver for ATI Radeon cards) for X, which didn’t work after the upgrade. For now, I’ve just gone back to using the normal radeon driver.

Lenny comes with Firefox 3 (aka iceweasel), and Thunderbird 2.0, so I’ve got an up to date browser and mail client. The new gnome icons look more polished and professional. So far, I like what I see.

css.php