.htaccess if statement

<If “%{REMOTE_ADDR} == ‘123.123.123.123’ || %{REMOTE_ADDR} == ‘456.456.456.456’”>

Options +Indexes

</If>

<Else>

Options -Indexes

</Else>

Resize mounted partition in Linux

You can resize only last partition at runtime

fdisk / gdisk

• Run sudo fdisk /dev/sda
• press p to list the partitions. Make note of the start cylinder of /dev/sda1 ex. 2048
• press d to delete existing partition
• press n to create new partition it is critical that the new partition starts at the same block as the old
• do not remove the signature
• press a and set boot flag

Reboot or use partprobe / kpartx to see new partition’s size

Resize filesystem

sudo resize2fs /dev/sda1

resize RAID partitions

Ensure that the RAID array is consistent and synchronized by entering

cat /proc/mdstat

If your RAID array is still synchronizing according to the output of this command, you must wait until synchronization is complete before continuing.

sudo mdadm /dev/md0 --fail /dev/sda1 --remove /dev/sda1

To succeed, both the fail and remove actions must be specified.

sudo mdadm -a /dev/md0 /dev/sda1

….

Wait until the RAID is synchronized and consistent before continuing with the next partition.

Repeat these steps for each of the remaining component devices in the array. Ensure that you modify the commands for the correct component partition.

If you get a message that tells you that the kernel could not re-read the partition table for the RAID, you must reboot the computer after all partitions have been resized to force an update of the partition table.

Remove second disk’s paritions from the RAID array:

sudo mdadm /dev/md0 --fail /dev/sda1 --remove /dev/sdb1
sudo mdadm /dev/md1 --fail /dev/sda5 --remove /dev/sdb5
sudo mdadm /dev/md2 --fail /dev/sda6 --remove /dev/sdb6
sudo mdadm /dev/md3 --fail /dev/sda7 --remove /dev/sdb7

Check the size of the array and the device size known to the array by entering

sudo mdadm -D /dev/md0 | grep -e "Array Size" -e "Dev Size"

Increase the size of the array to the maximum available size by entering

sudo mdadm --grow /dev/md0 -z max --assume-clean

The array uses any space that has been added to the devices, but this space will not be synchronized. This is recommended for RAID 1 because the synchronization is not needed. It can be useful for other RAID levels if the space that was added to the member devices was pre-zeroed.

Recheck the size of your array and the device size known to the array by entering

sudo mdadm -D /dev/md0 | grep -e "Array Size" -e "Dev Size"

If your array was not resized as you expected, you must reboot, then try this procedure again.

You can increase the size of the file system to the maximum space available or specify an exact size. When specifying an exact size for the file system, ensure that the new size satisfies the following conditions:

• The new size must be greater than the size of the existing data; otherwise, data loss occurs.
• The new size must be equal to or less than the current RAID size because the file system size cannot extend beyond the space available.

Increase the size of the partition on second disk, using a disk partitioner

Re-add the partition to the RAID array. For example, to add /dev/sdb1..x enter:

sudo mdadm -a /dev/md0 /dev/sdb1
sudo mdadm -a /dev/md1 /dev/sdb5
sudo mdadm -a /dev/md2 /dev/sdb6
sudo mdadm -a /dev/md3 /dev/sdb7

Resize RAID partition to max size

sudo resize2fs -p /dev/md0
sudo resize2fs -p /dev/md1
sudo resize2fs -p /dev/md2
sudo resize2fs -p /dev/md3

WHEN ALL PARTITIONS ARE REBUILDED run:

mdadm --detail --scan >> /etc/mdadm.conf

OpenVPN + Google Authenticator MFA

apt install libqrencode3 libpam-google-authenticator

addgroup gauth
useradd -g gauth gauth
mkdir /etc/openvpn/google-authenticator
chown gauth:gauth /etc/openvpn/google-authenticator
chmod 0700 /etc/openvpn/google-authenticator

add line in /etc/openvpn/server.conf

plugin /usr/lib/openvpn/openvpn-plugin-auth-pam.so openvpn

create /etc/pam.d/openvpn

with content:

auth required /usr/lib/x86_64-linux-gnu/security/pam_google_authenticator.so secret=/etc/openvpn/google-authenticator/${USER} user=gauth forward_pass

-t : Set up time-based (TOTP) verification

-d : Disallow reuse of previously used TOTP tokens

–r3 : Limit logins to N per every M seconds

-R30 :

-f : Write file without first confirming with user

-l : Override the default label in “otpauth://” URL

-i: Override the default issuer in “otpauth://” URL

-s : Specify a non-standard file location

replace <username> with certificate_name

google-authenticator -t -d -r3 -R30 -f -l “<username>” -i “Company VPN” -s /etc/openvpn/google-authenticator/username

chown gauth:gauth /etc/openvpn/google-authenticator/username

KVM – VNC Server from remote host

<graphics type=”vnc” port=”5900″ autoport=”yes” listen=”SERVER_IP” passwd=”SECRET_PASSWORD”>
<listen type=”address” address=”SERVER_IP”/>
</graphics>

KVM validate xml

Dump

virsh dumpxml debian11 > test.xml
virt-xml-validate test.xml

RRDTools

./configure –enable-perl-site-install

Cpan – Encode.c: loadable library and perl binaries are mismatched (got handshake key 0xed00080, needed 0xeb00080)

Move the folder /usr/local/lib64/perl5 to /usr/local/lib64/BADperl5

Move the folder /usr/local/share/perl5 to /usr/local/share/BADperl5

KVM Snapshots

Convert snapshot to standalone image

qemu-img convert -O qcow2 <snapshot.img> <new-image.img>

Create

virsh snapshot-create-as --domain debian11 --name debian11_snapshot01

List

virsh snapshot-create-as --domain debian11 --name debian11_snapshot01

Restore

virsh snapshot-revert debian11 debian11_snapshot01

Delete

virsh snapshot-delete --domain debian11 --snapshotname debian11_snapshot01

Info

virsh snapshot-info --domain debian11 --snapshotname debian11_snapshot01

OpenVPN – don’t change route

add

pull-filter ignore redirect-gateway

to client.ovpn file