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Month: July 2015

WordPress – password protect

Posted on by mihai

Ok, in order to harden your WordPress installation, the easiest and fastest thing you can do is to add another layer of authentication to wp-admin area.
If your web server is Apache, you can use htaccess files to do this.

First, create the user and password file. Use a Htpasswd generator and make sure to put the path outside the document root of your website.

Now, you need to edit two .htaccess files.

The one in wp-admin/.htaccess (create it if it doesn’t exists) should contain these lines:


#Avoid the too many redirects error
ErrorDocument 401 "Denied"
ErrorDocument 403 "Denied"

# Allow plugin access to admin-ajax.php around password protection

Order allow,deny
Allow from all
Satisfy any

#Basic authentication
AuthType Basic
AuthName "Secure Area"
AuthUserFile "/path/to/.htpasswd"
require valid-user

And in the main .htaccess file from the document root of your website, add these lines after the WordPress rewrite rules:


#Avoid the too many redirects error
ErrorDocument 401 "Denied"
ErrorDocument 403 "Denied"


AuthType Basic
AuthName "Secure Area"
AuthUserFile "/path/to/.htpasswd"
require valid-user

I’ll update this post with the nGinx configuration, if that’s your case.

Entropy

Posted on by mihai

I was working on a Debian 5 (Lenny) box and needed to generate a key.
So, ok, let’s do gpg �gen-key , filled in the required info, and let’s generate that key, when, suddenly:

We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
+++++++++++++++++++++.+++++++++++++++++++++++++.+++++�++++++++++..+++++..++++++++++.+++++.++++++++++>+++++����.+++++

Not enough random bytes available. Please do some other work to give
the OS a chance to collect more entropy! (Need 258 more bytes)

What? What entropy? Do what? Use the keyboard, disk ?
Well, apparently, there is no joke, you really need some activity going on the system in order to generate the key.

I did ls -R / and it started to generate the key.

To see the entropy of the system: cat /proc/sys/kernel/random/entropy_avail

Now I wonder, do we have entropy on Windows?

ESX � How to Power off an unresponsive VM

Posted on by mihai

It happened to me the other day, the vm was stuck because another process was locked (a snapshot in my case).

I found out that the best way is this:

1. Log in to ESX console and determine the WorldID with the command:

# vm-support -x

2. Determine the master world ID with the command:

# less -S /proc/vmware/vm/****/cpu/status

or on Vsphere

less -S /proc/vmware/vm/****/names

3. Scroll to the right with the arrow keys until you see the group field. It appears similar to:

Group
vm.****

4. Run the following command to shut the virtual machine down with the group ID:

# /usr/lib/vmware/bin/vmkload_app -k 9 ****

If the preceding steps fail, perform the following steps for an ESX 4.x host:

1. List all running virtual machines to find the vmxCartelID of the affected virtual machine with the command:

# /usr/lib/vmware/bin/vmdumper -l

2. Scroll through the list until you see your virtual machine�s name. The output appears similar to:

vmid=5151 pid=-1 cfgFile=�/vmfs/volumes/4a16a48a-d807aa7e-e674-001e4ffc52e9/mdineeen_test/vm_test.vmx� uuid=�56 4d a6 db 0a e2 e5 3e-a9 2b 31 4b 69 29 15 19? displayName=�vm_test� vmxCartelID=####

3. Run the following command to shut the virtual machine down with the vmxCartelID:

# /usr/lib/vmware/bin/vmkload_app -k 9 ####

How to resize LVM (extend or reduce)

Posted on by mihai

Logical Volume Manager is great, you can manage your disks and partitions in volumes. The most common task is to extend a volume or reduce one.

You can extend a volume while the system is running, which is preaty great. Here�s how:

1. Let say your physical disk is /dev/sda, you already have two partitions (/dev/sda1 and /dev/sda2) and want to extend the rest of the free space. fdisk /dev/sda and create a new partition /dev/sda3

2.� pvcreate /dev/sda3

3.��vgextend VolGroup00 /dev/sda3

4.�� lvextend /dev/VolGroup00/LogVol00 /dev/sda3

5.�� resize2fs /dev/VolGroup00/LogVol00

Now, asume that we want to reduce. This is a little bit tricky, you can not do it on the fly. You have to boot with a rescue cd (can be CentOS cd1 and type linux rescue at prompt).

1. lvm vgchange -a y

2. e2fsck -f /dev/VolGroup00/LogVol00

3. resize2fs -f /dev/VolGroup00/LogVol00 20G

4. lvm lvreduce -L10G /dev/VolGroup00/LogVol00

Happy resizing !

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