Linux and Logitech MX Anywhere 3

This mouse feels good to touch. It just feels nice. The scroll wheel, called Magspeed Wheel, feels really good to use with its tactile feeling. However try pressing the black button in the middle – then it changed from Ratchet mode to Freespin mode , basically it flies. You can spin it really, really fast. Awesome.

However, Logitech does not provide its configuration software on Linux. But no worries, we can use LogiOps for that.

Copy-paste these lines to set it up ; these are for Ubuntu 20.04, if you’re using different Linux distro, you might need to change some of it.

sudo apt-get install -y install cmake libevdev-dev libudev-dev libconfig++-dev

cd /tmp ; wget ; mkdir tmp ; cd tmp ; unzip ../ ; cd logiops-master ; mkdir build ; cd build

cmake .. ; make ; sudo make install 

sudo nano /etc/logid.cfg

sudo systemctl enable --now logid

You may notice that we’re creating a configuration file name logid.cfg , there’s a [ guide to create it ], however some may find it confusing.

Therefore please find a sample logid.cfg for MX Anywhere 3 below. It will enable a reasonably nice usage of the device, and also enable you to change the mouse’s DPI by pressing the side buttons.


// Logiops (Linux driver) configuration for Logitech MX Master 3.
// Includes gestures, smartshift, DPI.
// Tested on logid v0.2.2-35-g1c209ed.

// File location: /etc/logid.cfg

devices: ({
  name: "MX Anywhere 3";

  smartshift: {
    on: true;
    threshold: 15;

  hiresscroll: {
    hires: true;
    invert: false;
    target: true;
       up: {
            mode: "Axis";
            axis: "REL_WHEEL_HI_RES";
            axis_multiplier: 1;
        down: {
            mode: "Axis";
            axis: "REL_WHEEL_HI_RES";
            axis_multiplier: -1;

  dpi: 1600; // max=4000

    buttons: (
            cid: 0x52;
            action =
                type: "Gestures";
                gestures: (
                        direction: "Left";
                        mode: "OnInterval";
			interval: 10;
                        action =
                            type: "Keypress";
                            keys: ["KEY_VOLUMEDOWN"];
                        direction: "Right";
                        mode: "OnInterval";
			interval: 10;
                        action =
                            type: "Keypress";
                            keys: ["KEY_VOLUMEUP"];
                        direction: "None"
                        mode: "OnRelease";
                        action =
			    type: "Keypress";
			    keys: ["BTN_MIDDLE"];
            cid: 0x53;
            action =
//                type: "Keypress";
//                keys: ["KEY_BACK"];
		type: "ChangeDPI";
              	inc: -1000;            
            cid: 0x56;
            action =
//                type: "Keypress";
//                keys: ["KEY_FORWARD"];
		type: "ChangeDPI";
              	inc: 1000;            

How to play Roblox on Linux

I used to play Roblox with my kids from my Linux-based (Ubuntu) laptop – by having a virtual machine set up (on VirtualBox) with Windows, and play there. Of course it’s slow, but I still CAN play.

However one day Roblox decided to disable playing from Virtual Machine. And there goes my little bit of happiness with my children.

One day I found this article about using Steam Link to enable remote access to a Windows desktop, and it got me an idea – can I use this trick to play Roblox again from my laptop?

So I setup Google Chrome to be streamable from my gaming computer on my house’s second floor – and voila, it showed up in my Steam account indeed !

By invoking Google Chrome on my Steam app on Linux – then I can browse to, and then play all the games there.

Mission accomplished !

Use Steam to Stream Your Desktop Instead of Your Games :

Setup OpenVPN Server on Proxmox LXC

I needed to do this, but all the tutorials that I could find are incomplete, or already outdated, such as this.

After hacking around for a while, here’s how to correctly setup OpenVPN server in a container on Proxmox:

(btw if you just need to setup an OpenVPN Server in a normal server / non-container, then just do the “in container” part below)


# create special device "tun" for OpenVPN
mkdir -p /devcontainer/net
mknod /devcontainer/net/tun c 10 200
chown 100000:100000 /devcontainer/net/tun

# enable your container to use that tun device
# change 124 into your container's number : pct list
echo "lxc.mount.entry: /devcontainer/net dev/net none bind,create=dir" >> /etc/pve/lxc/124.conf

# forward OpenVPN traffic to your container's IP address
# change to your container's IP address
iptables -t nat -A PREROUTING -i vmbr0 -p tcp -m tcp --dport 1194 -j DNAT --to-destination

iptables -t nat -A PREROUTING -i vmbr0 -p udp -m udp --dport 1194 -j DNAT --to-destination

iptables -t nat -A PREROUTING -i vmbr1 -p tcp -m tcp --dport 53 -j DNAT --to-destination

# save iptables's rule
iptables-save > /etc/iptables.rules


# execute the automated OpenVPN installation script 
mkdir /root/scripts
cd /root/scripts

wget --no-check-certificate -O ; chmod +x ; ./
# if you'd like to change the default IP address, do this :
# vi
# :%s/10.8.0/10.88.0/g

# setup NAT, so the OpenVPN clients can connect to the internet 
# while connected to this OpenVPN server
iptables -I POSTROUTING -t nat -s -j MASQUERADE

# save iptables's rule
iptables-save > /etc/iptables.rules

After executing the /root/scripts/ script , it will result in a file with ovpn extension

Download that to your computer / client,
install OpenVPN client,
and use that ovpn file as the configuration

Enjoy !

In case that very helpful OpenVPN Server install script suddenly disappear, here it is :

# Copyright (c) 2013 Nyr. Released under the MIT License.

# Detect Debian users running the script with "sh" instead of bash
if readlink /proc/$$/exe | grep -q "dash"; then
	echo 'This installer needs to be run with "bash", not "sh".'

# Discard stdin. Needed when running from an one-liner which includes a newline
read -N 999999 -t 0.001

# Detect OpenVZ 6
if [[ $(uname -r | cut -d "." -f 1) -eq 2 ]]; then
	echo "The system is running an old kernel, which is incompatible with this installer."

# Detect OS
# $os_version variables aren't always in use, but are kept here for convenience
if grep -qs "ubuntu" /etc/os-release; then
	os_version=$(grep 'VERSION_ID' /etc/os-release | cut -d '"' -f 2 | tr -d '.')
elif [[ -e /etc/debian_version ]]; then
	os_version=$(grep -oE '[0-9]+' /etc/debian_version | head -1)
elif [[ -e /etc/centos-release ]]; then
	os_version=$(grep -oE '[0-9]+' /etc/centos-release | head -1)
elif [[ -e /etc/fedora-release ]]; then
	os_version=$(grep -oE '[0-9]+' /etc/fedora-release | head -1)
	echo "This installer seems to be running on an unsupported distribution.
Supported distributions are Ubuntu, Debian, CentOS, and Fedora."

if [[ "$os" == "ubuntu" && "$os_version" -lt 1804 ]]; then
	echo "Ubuntu 18.04 or higher is required to use this installer.
This version of Ubuntu is too old and unsupported."

if [[ "$os" == "debian" && "$os_version" -lt 9 ]]; then
	echo "Debian 9 or higher is required to use this installer.
This version of Debian is too old and unsupported."

if [[ "$os" == "centos" && "$os_version" -lt 7 ]]; then
	echo "CentOS 7 or higher is required to use this installer.
This version of CentOS is too old and unsupported."

# Detect environments where $PATH does not include the sbin directories
if ! grep -q sbin <<< "$PATH"; then
	echo '$PATH does not include sbin. Try using "su -" instead of "su".'

if [[ "$EUID" -ne 0 ]]; then
	echo "This installer needs to be run with superuser privileges."

if [[ ! -e /dev/net/tun ]] || ! ( exec 7<>/dev/net/tun ) 2>/dev/null; then
	echo "The system does not have the TUN device available.
TUN needs to be enabled before running this installer."

new_client () {
	# Generates the custom client.ovpn
	cat /etc/openvpn/server/client-common.txt
	echo "<ca>"
	cat /etc/openvpn/server/easy-rsa/pki/ca.crt
	echo "</ca>"
	echo "<cert>"
	sed -ne '/BEGIN CERTIFICATE/,$ p' /etc/openvpn/server/easy-rsa/pki/issued/"$client".crt
	echo "</cert>"
	echo "<key>"
	cat /etc/openvpn/server/easy-rsa/pki/private/"$client".key
	echo "</key>"
	echo "<tls-crypt>"
	sed -ne '/BEGIN OpenVPN Static key/,$ p' /etc/openvpn/server/tc.key
	echo "</tls-crypt>"
	} > ~/"$client".ovpn

if [[ ! -e /etc/openvpn/server/server.conf ]]; then
	echo 'Welcome to this OpenVPN road warrior installer!'
	# If system has a single IPv4, it is selected automatically. Else, ask the user
	if [[ $(ip -4 addr | grep inet | grep -vEc '127(\.[0-9]{1,3}){3}') -eq 1 ]]; then
		ip=$(ip -4 addr | grep inet | grep -vE '127(\.[0-9]{1,3}){3}' | cut -d '/' -f 1 | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}')
		number_of_ip=$(ip -4 addr | grep inet | grep -vEc '127(\.[0-9]{1,3}){3}')
		echo "Which IPv4 address should be used?"
		ip -4 addr | grep inet | grep -vE '127(\.[0-9]{1,3}){3}' | cut -d '/' -f 1 | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | nl -s ') '
		read -p "IPv4 address [1]: " ip_number
		until [[ -z "$ip_number" || "$ip_number" =~ ^[0-9]+$ && "$ip_number" -le "$number_of_ip" ]]; do
			echo "$ip_number: invalid selection."
			read -p "IPv4 address [1]: " ip_number
		[[ -z "$ip_number" ]] && ip_number="1"
		ip=$(ip -4 addr | grep inet | grep -vE '127(\.[0-9]{1,3}){3}' | cut -d '/' -f 1 | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | sed -n "$ip_number"p)
	# If $ip is a private IP address, the server must be behind NAT
	if echo "$ip" | grep -qE '^(10\.|172\.1[6789]\.|172\.2[0-9]\.|172\.3[01]\.|192\.168)'; then
		echo "This server is behind NAT. What is the public IPv4 address or hostname?"
		# Get public IP and sanitize with grep
		get_public_ip=$(grep -m 1 -oE '^[0-9]{1,3}(\.[0-9]{1,3}){3}$' <<< "$(wget -T 10 -t 1 -4qO- "" || curl -m 10 -4Ls "")")
		read -p "Public IPv4 address / hostname [$get_public_ip]: " public_ip
		# If the checkip service is unavailable and user didn't provide input, ask again
		until [[ -n "$get_public_ip" || -n "$public_ip" ]]; do
			echo "Invalid input."
			read -p "Public IPv4 address / hostname: " public_ip
		[[ -z "$public_ip" ]] && public_ip="$get_public_ip"
	# If system has a single IPv6, it is selected automatically
	if [[ $(ip -6 addr | grep -c 'inet6 [23]') -eq 1 ]]; then
		ip6=$(ip -6 addr | grep 'inet6 [23]' | cut -d '/' -f 1 | grep -oE '([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}')
	# If system has multiple IPv6, ask the user to select one
	if [[ $(ip -6 addr | grep -c 'inet6 [23]') -gt 1 ]]; then
		number_of_ip6=$(ip -6 addr | grep -c 'inet6 [23]')
		echo "Which IPv6 address should be used?"
		ip -6 addr | grep 'inet6 [23]' | cut -d '/' -f 1 | grep -oE '([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}' | nl -s ') '
		read -p "IPv6 address [1]: " ip6_number
		until [[ -z "$ip6_number" || "$ip6_number" =~ ^[0-9]+$ && "$ip6_number" -le "$number_of_ip6" ]]; do
			echo "$ip6_number: invalid selection."
			read -p "IPv6 address [1]: " ip6_number
		[[ -z "$ip6_number" ]] && ip6_number="1"
		ip6=$(ip -6 addr | grep 'inet6 [23]' | cut -d '/' -f 1 | grep -oE '([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}' | sed -n "$ip6_number"p)
	echo "Which protocol should OpenVPN use?"
	echo "   1) UDP (recommended)"
	echo "   2) TCP"
	read -p "Protocol [1]: " protocol
	until [[ -z "$protocol" || "$protocol" =~ ^[12]$ ]]; do
		echo "$protocol: invalid selection."
		read -p "Protocol [1]: " protocol
	case "$protocol" in
	echo "What port should OpenVPN listen to?"
	read -p "Port [1194]: " port
	until [[ -z "$port" || "$port" =~ ^[0-9]+$ && "$port" -le 65535 ]]; do
		echo "$port: invalid port."
		read -p "Port [1194]: " port
	[[ -z "$port" ]] && port="1194"
	echo "Select a DNS server for the clients:"
	echo "   1) Current system resolvers"
	echo "   2) Google"
	echo "   3)"
	echo "   4) OpenDNS"
	echo "   5) Quad9"
	echo "   6) AdGuard"
	read -p "DNS server [1]: " dns
	until [[ -z "$dns" || "$dns" =~ ^[1-6]$ ]]; do
		echo "$dns: invalid selection."
		read -p "DNS server [1]: " dns
	echo "Enter a name for the first client:"
	read -p "Name [client]: " unsanitized_client
	# Allow a limited set of characters to avoid conflicts
	client=$(sed 's/[^0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-]/_/g' <<< "$unsanitized_client")
	[[ -z "$client" ]] && client="client"
	echo "OpenVPN installation is ready to begin."
	# Install a firewall in the rare case where one is not already available
	if ! systemctl is-active --quiet firewalld.service && ! hash iptables 2>/dev/null; then
		if [[ "$os" == "centos" || "$os" == "fedora" ]]; then
			# We don't want to silently enable firewalld, so we give a subtle warning
			# If the user continues, firewalld will be installed and enabled during setup
			echo "firewalld, which is required to manage routing tables, will also be installed."
		elif [[ "$os" == "debian" || "$os" == "ubuntu" ]]; then
			# iptables is way less invasive than firewalld so no warning is given
	read -n1 -r -p "Press any key to continue..."
	# If running inside a container, disable LimitNPROC to prevent conflicts
	if systemd-detect-virt -cq; then
		mkdir /etc/systemd/system/openvpn-server@server.service.d/ 2>/dev/null
		echo "[Service]
LimitNPROC=infinity" > /etc/systemd/system/openvpn-server@server.service.d/disable-limitnproc.conf
	if [[ "$os" = "debian" || "$os" = "ubuntu" ]]; then
		apt-get update
		apt-get install -y openvpn openssl ca-certificates $firewall
	elif [[ "$os" = "centos" ]]; then
		yum install -y epel-release
		yum install -y openvpn openssl ca-certificates tar $firewall
		# Else, OS must be Fedora
		dnf install -y openvpn openssl ca-certificates tar $firewall
	# If firewalld was just installed, enable it
	if [[ "$firewall" == "firewalld" ]]; then
		systemctl enable --now firewalld.service
	# Get easy-rsa
	mkdir -p /etc/openvpn/server/easy-rsa/
	{ wget -qO- "$easy_rsa_url" 2>/dev/null || curl -sL "$easy_rsa_url" ; } | tar xz -C /etc/openvpn/server/easy-rsa/ --strip-components 1
	chown -R root:root /etc/openvpn/server/easy-rsa/
	cd /etc/openvpn/server/easy-rsa/
	# Create the PKI, set up the CA and the server and client certificates
	./easyrsa init-pki
	./easyrsa --batch build-ca nopass
	EASYRSA_CERT_EXPIRE=3650 ./easyrsa build-server-full server nopass
	EASYRSA_CERT_EXPIRE=3650 ./easyrsa build-client-full "$client" nopass
	EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
	# Move the stuff we need
	cp pki/ca.crt pki/private/ca.key pki/issued/server.crt pki/private/server.key pki/crl.pem /etc/openvpn/server
	# CRL is read with each client connection, while OpenVPN is dropped to nobody
	chown nobody:"$group_name" /etc/openvpn/server/crl.pem
	# Without +x in the directory, OpenVPN can't run a stat() on the CRL file
	chmod o+x /etc/openvpn/server/
	# Generate key for tls-crypt
	openvpn --genkey --secret /etc/openvpn/server/tc.key
	# Create the DH parameters file using the predefined ffdhe2048 group
	echo '-----BEGIN DH PARAMETERS-----
-----END DH PARAMETERS-----' > /etc/openvpn/server/dh.pem
	# Generate server.conf
	echo "local $ip
port $port
proto $protocol
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh.pem
auth SHA512
tls-crypt tc.key
topology subnet
server" > /etc/openvpn/server/server.conf
	# IPv6
	if [[ -z "$ip6" ]]; then
		echo 'push "redirect-gateway def1 bypass-dhcp"' >> /etc/openvpn/server/server.conf
		echo 'server-ipv6 fddd:1194:1194:1194::/64' >> /etc/openvpn/server/server.conf
		echo 'push "redirect-gateway def1 ipv6 bypass-dhcp"' >> /etc/openvpn/server/server.conf
	echo 'ifconfig-pool-persist ipp.txt' >> /etc/openvpn/server/server.conf
	# DNS
	case "$dns" in
			# Locate the proper resolv.conf
			# Needed for systems running systemd-resolved
			if grep -q '^nameserver' "/etc/resolv.conf"; then
			# Obtain the resolvers from resolv.conf and use them for OpenVPN
			grep -v '^#\|^;' "$resolv_conf" | grep '^nameserver' | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | while read line; do
				echo "push \"dhcp-option DNS $line\"" >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
			echo 'push "dhcp-option DNS"' >> /etc/openvpn/server/server.conf
	echo "keepalive 10 120
cipher AES-256-CBC
user nobody
group $group_name
status openvpn-status.log
verb 3
crl-verify crl.pem" >> /etc/openvpn/server/server.conf
	if [[ "$protocol" = "udp" ]]; then
		echo "explicit-exit-notify" >> /etc/openvpn/server/server.conf
	# Enable net.ipv4.ip_forward for the system
	echo 'net.ipv4.ip_forward=1' > /etc/sysctl.d/30-openvpn-forward.conf
	# Enable without waiting for a reboot or service restart
	echo 1 > /proc/sys/net/ipv4/ip_forward
	if [[ -n "$ip6" ]]; then
		# Enable net.ipv6.conf.all.forwarding for the system
		echo "net.ipv6.conf.all.forwarding=1" >> /etc/sysctl.d/30-openvpn-forward.conf
		# Enable without waiting for a reboot or service restart
		echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
	if systemctl is-active --quiet firewalld.service; then
		# Using both permanent and not permanent rules to avoid a firewalld
		# reload.
		# We don't use --add-service=openvpn because that would only work with
		# the default port and protocol.
		firewall-cmd --add-port="$port"/"$protocol"
		firewall-cmd --zone=trusted --add-source=
		firewall-cmd --permanent --add-port="$port"/"$protocol"
		firewall-cmd --permanent --zone=trusted --add-source=
		# Set NAT for the VPN subnet
		firewall-cmd --direct --add-rule ipv4 nat POSTROUTING 0 -s ! -d -j SNAT --to "$ip"
		firewall-cmd --permanent --direct --add-rule ipv4 nat POSTROUTING 0 -s ! -d -j SNAT --to "$ip"
		if [[ -n "$ip6" ]]; then
			firewall-cmd --zone=trusted --add-source=fddd:1194:1194:1194::/64
			firewall-cmd --permanent --zone=trusted --add-source=fddd:1194:1194:1194::/64
			firewall-cmd --direct --add-rule ipv6 nat POSTROUTING 0 -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to "$ip6"
			firewall-cmd --permanent --direct --add-rule ipv6 nat POSTROUTING 0 -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to "$ip6"
		# Create a service to set up persistent iptables rules
		iptables_path=$(command -v iptables)
		ip6tables_path=$(command -v ip6tables)
		# nf_tables is not available as standard in OVZ kernels. So use iptables-legacy
		# if we are in OVZ, with a nf_tables backend and iptables-legacy is available.
		if [[ $(systemd-detect-virt) == "openvz" ]] && readlink -f "$(command -v iptables)" | grep -q "nft" && hash iptables-legacy 2>/dev/null; then
			iptables_path=$(command -v iptables-legacy)
			ip6tables_path=$(command -v ip6tables-legacy)
		echo "[Unit]
ExecStart=$iptables_path -t nat -A POSTROUTING -s ! -d -j SNAT --to $ip
ExecStart=$iptables_path -I INPUT -p $protocol --dport $port -j ACCEPT
ExecStart=$iptables_path -I FORWARD -s -j ACCEPT
ExecStart=$iptables_path -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
ExecStop=$iptables_path -t nat -D POSTROUTING -s ! -d -j SNAT --to $ip
ExecStop=$iptables_path -D INPUT -p $protocol --dport $port -j ACCEPT
ExecStop=$iptables_path -D FORWARD -s -j ACCEPT
ExecStop=$iptables_path -D FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT" > /etc/systemd/system/openvpn-iptables.service
		if [[ -n "$ip6" ]]; then
			echo "ExecStart=$ip6tables_path -t nat -A POSTROUTING -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to $ip6
ExecStart=$ip6tables_path -I FORWARD -s fddd:1194:1194:1194::/64 -j ACCEPT
ExecStart=$ip6tables_path -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
ExecStop=$ip6tables_path -t nat -D POSTROUTING -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to $ip6
ExecStop=$ip6tables_path -D FORWARD -s fddd:1194:1194:1194::/64 -j ACCEPT
ExecStop=$ip6tables_path -D FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT" >> /etc/systemd/system/openvpn-iptables.service
		echo "RemainAfterExit=yes
[Install]" >> /etc/systemd/system/openvpn-iptables.service
		systemctl enable --now openvpn-iptables.service
	# If SELinux is enabled and a custom port was selected, we need this
	if sestatus 2>/dev/null | grep "Current mode" | grep -q "enforcing" && [[ "$port" != 1194 ]]; then
		# Install semanage if not already present
		if ! hash semanage 2>/dev/null; then
			if [[ "$os_version" -eq 7 ]]; then
				# Centos 7
				yum install -y policycoreutils-python
				# CentOS 8 or Fedora
				dnf install -y policycoreutils-python-utils
		semanage port -a -t openvpn_port_t -p "$protocol" "$port"
	# If the server is behind NAT, use the correct IP address
	[[ -n "$public_ip" ]] && ip="$public_ip"
	# client-common.txt is created so we have a template to add further users later
	echo "client
dev tun
proto $protocol
remote $ip $port
resolv-retry infinite
remote-cert-tls server
auth SHA512
cipher AES-256-CBC
ignore-unknown-option block-outside-dns
verb 3" > /etc/openvpn/server/client-common.txt
	# Enable and start the OpenVPN service
	systemctl enable --now openvpn-server@server.service
	# Generates the custom client.ovpn
	echo "Finished!"
	echo "The client configuration is available in:" ~/"$client.ovpn"
	echo "New clients can be added by running this script again."
	echo "OpenVPN is already installed."
	echo "Select an option:"
	echo "   1) Add a new client"
	echo "   2) Revoke an existing client"
	echo "   3) Remove OpenVPN"
	echo "   4) Exit"
	read -p "Option: " option
	until [[ "$option" =~ ^[1-4]$ ]]; do
		echo "$option: invalid selection."
		read -p "Option: " option
	case "$option" in
			echo "Provide a name for the client:"
			read -p "Name: " unsanitized_client
			client=$(sed 's/[^0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-]/_/g' <<< "$unsanitized_client")
			while [[ -z "$client" || -e /etc/openvpn/server/easy-rsa/pki/issued/"$client".crt ]]; do
				echo "$client: invalid name."
				read -p "Name: " unsanitized_client
				client=$(sed 's/[^0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-]/_/g' <<< "$unsanitized_client")
			cd /etc/openvpn/server/easy-rsa/
			EASYRSA_CERT_EXPIRE=3650 ./easyrsa build-client-full "$client" nopass
			# Generates the custom client.ovpn
			echo "$client added. Configuration available in:" ~/"$client.ovpn"
			# This option could be documented a bit better and maybe even be simplified
			# ...but what can I say, I want some sleep too
			number_of_clients=$(tail -n +2 /etc/openvpn/server/easy-rsa/pki/index.txt | grep -c "^V")
			if [[ "$number_of_clients" = 0 ]]; then
				echo "There are no existing clients!"
			echo "Select the client to revoke:"
			tail -n +2 /etc/openvpn/server/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | nl -s ') '
			read -p "Client: " client_number
			until [[ "$client_number" =~ ^[0-9]+$ && "$client_number" -le "$number_of_clients" ]]; do
				echo "$client_number: invalid selection."
				read -p "Client: " client_number
			client=$(tail -n +2 /etc/openvpn/server/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | sed -n "$client_number"p)
			read -p "Confirm $client revocation? [y/N]: " revoke
			until [[ "$revoke" =~ ^[yYnN]*$ ]]; do
				echo "$revoke: invalid selection."
				read -p "Confirm $client revocation? [y/N]: " revoke
			if [[ "$revoke" =~ ^[yY]$ ]]; then
				cd /etc/openvpn/server/easy-rsa/
				./easyrsa --batch revoke "$client"
				EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
				rm -f /etc/openvpn/server/crl.pem
				cp /etc/openvpn/server/easy-rsa/pki/crl.pem /etc/openvpn/server/crl.pem
				# CRL is read with each client connection, when OpenVPN is dropped to nobody
				chown nobody:"$group_name" /etc/openvpn/server/crl.pem
				echo "$client revoked!"
				echo "$client revocation aborted!"
			read -p "Confirm OpenVPN removal? [y/N]: " remove
			until [[ "$remove" =~ ^[yYnN]*$ ]]; do
				echo "$remove: invalid selection."
				read -p "Confirm OpenVPN removal? [y/N]: " remove
			if [[ "$remove" =~ ^[yY]$ ]]; then
				port=$(grep '^port ' /etc/openvpn/server/server.conf | cut -d " " -f 2)
				protocol=$(grep '^proto ' /etc/openvpn/server/server.conf | cut -d " " -f 2)
				if systemctl is-active --quiet firewalld.service; then
					ip=$(firewall-cmd --direct --get-rules ipv4 nat POSTROUTING | grep '\-s '"'"'!'"'"' -d' | grep -oE '[^ ]+$')
					# Using both permanent and not permanent rules to avoid a firewalld reload.
					firewall-cmd --remove-port="$port"/"$protocol"
					firewall-cmd --zone=trusted --remove-source=
					firewall-cmd --permanent --remove-port="$port"/"$protocol"
					firewall-cmd --permanent --zone=trusted --remove-source=
					firewall-cmd --direct --remove-rule ipv4 nat POSTROUTING 0 -s ! -d -j SNAT --to "$ip"
					firewall-cmd --permanent --direct --remove-rule ipv4 nat POSTROUTING 0 -s ! -d -j SNAT --to "$ip"
					if grep -qs "server-ipv6" /etc/openvpn/server/server.conf; then
						ip6=$(firewall-cmd --direct --get-rules ipv6 nat POSTROUTING | grep '\-s fddd:1194:1194:1194::/64 '"'"'!'"'"' -d fddd:1194:1194:1194::/64' | grep -oE '[^ ]+$')
						firewall-cmd --zone=trusted --remove-source=fddd:1194:1194:1194::/64
						firewall-cmd --permanent --zone=trusted --remove-source=fddd:1194:1194:1194::/64
						firewall-cmd --direct --remove-rule ipv6 nat POSTROUTING 0 -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to "$ip6"
						firewall-cmd --permanent --direct --remove-rule ipv6 nat POSTROUTING 0 -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to "$ip6"
					systemctl disable --now openvpn-iptables.service
					rm -f /etc/systemd/system/openvpn-iptables.service
				if sestatus 2>/dev/null | grep "Current mode" | grep -q "enforcing" && [[ "$port" != 1194 ]]; then
					semanage port -d -t openvpn_port_t -p "$protocol" "$port"
				systemctl disable --now openvpn-server@server.service
				rm -rf /etc/openvpn/server
				rm -f /etc/systemd/system/openvpn-server@server.service.d/disable-limitnproc.conf
				rm -f /etc/sysctl.d/30-openvpn-forward.conf
				if [[ "$os" = "debian" || "$os" = "ubuntu" ]]; then
					apt-get remove --purge -y openvpn
					# Else, OS must be CentOS or Fedora
					yum remove -y openvpn
				echo "OpenVPN removed!"
				echo "OpenVPN removal aborted!"

OBS (Open Broadcasting Software) As Video source (for Zoom, Google Meet, Skype, etc) in Ubuntu 20.04

I used to use my Android smartphone as webcam for Zoom / Skype / Google Meet / etc because my laptop’s webcam is so bad. This is possible thanks to the Droidcam app.

But sometimes there are problems, like the wifi got interference so the video would slow down or freeze for a while. And for long conference / meeting, it got my phone pretty hot because sometimes I have to charge it. And of course I can’t use my phone while it’s being used as webcam.

So I bought Logitech C920 Pro webcam, and started using it instead. In Linux it’s recognized and can bs used straight away.
But you may need to tweak its image quality a bit using guvcview before being used for work.

The picture quality is not as good as my smartphone’s , because my smartphone is heavily processing the images, so it came out even with HDR quality, in real-time. But as a daily work webcam, this Logitech webcam is good enough.

Then I need to start using Green screen as well with this webcam. There’s one problem – my Green screen is not wide enough to cover the webcam’s wide angle.

With Droidcam, this is not a problem, there’s a “Zoom” feature. So I just Zoom-in, until the green screen fills the view.
But since Logitech does not provide any kind of software for this webcam on Linux, I use OBS instead.

Using OBS, I can set up green screen in it, so we don’t need to use Zoom’s green screen / Virtual Background feature. And also that means all other software (Google Meet, Skype, etc) will automatically got the already green screened video from OBS.

To zoom-in in OBS, I just enlarge the webcam’s image box, until the green screen fill the view.
To activate green screen, I use the Chroma key filter.

choose Tools – V4L2 Video Output to enable OBS as Video Source for other software
Make sure to tick the “Auto Start” option
(no green screen tho when I took this screenshot)

To make OBS become a video source, we’ll need to install obs-v4l2sink :

Turned out there are a few problems installing it in Ubuntu 20.04 , we’ll discuss here the workaround for those:

# Another possible solution is using Snap's version of OBS, 
# which already include v4l2loopback kernel module 
# & obs-v4l2sink plugin
# sudo snap install obs-studio.
# sudo modprobe v4l2loopback video_nr=10 card_label=โ€OBS Video Sourceโ€ exclusive_caps=1

# If by any reason you can't use this Snap-based solution, 
# then continue : 

# download needed software for compilation
sudo apt-get update ; sudo apt-get install -y install obs-studio git cmake build-essential libobs-dev ffmpeg qtbase5-dev

cd /tmp ; mkdir myobscode ; cd myobscode

# get OBS' source code
git clone --recursive

# get plugin's source code
git clone

# compile the OBS plugin
cd ~/obs-v4l2sink
mkdir build && cd build
cmake -DLIBOBS_INCLUDE_DIR="../../obs-studio/libobs" -DCMAKE_INSTALL_PREFIX=/usr ..

make -j4
sudo make install
sudo cp /usr/lib/obs-plugins/
sudo cp /usr/lib/obs-plugins/ /usr/lib/x86_64-linux-gnu/obs-plugins/

# Turned out we need to compile and build v4l2loopback by ourselves - this is because the Ubuntu's version is too old
# Thanks to user jplandrain : 
cd ..
sudo apt-get remove v4l2loopback-dkms
git clone --branch v0.12.5
cd v4l2loopback
make && sudo make install

# make v4l2loopback automatically loaded by kernel after reboot
echo "v4l2loopback" >> /etc/modules-load.d/modules.conf
echo 'options v4l2loopback video_nr=2' >> /etc/modprobe.d/v4l2loopback.conf

echo 'options v4l2loopback card_label="VirtualCam"' >> /etc/modprobe.d/v4l2loopback.conf

echo 'options v4l2loopback exclusive_caps=1' >> /etc/modprobe.d/v4l2loopback.conf

# load the loopback module into kernel now
sudo modprobe v4l2loopback video_nr=10 card_label="OBS Video Source" exclusive_caps=1

# start OBS - now there should be a new menu : 
#     Tools - V4L2 Video Output
# also you'll need to tick "Autostart" option after choosing that menu
obs &

How to run Proxmox with only a single public IP address

IPv4 address is becoming rarer by each day. In some cases, it can be pretty hard to get multiple IPv4 address for your Proxmox server.

Thankfully, Proxmox is basically a Debian Linux OS with Proxmox layer on top of that. So that gives us quite a lot of flexibility.

This tutorial will help you to create a fully functional Proxmox server running multiple containers & virtual machines, using only a single IPv4 address.

These are the main steps :

  1. Create port forwarding rules
  2. Make sure it’s executed automatically everytime the server is restarted
  3. Setup a reverse-proxy server : to forward HTTP/S requests to the correct container / virtual machine
  4. Setup HTTPS

For CT (container) / VM (virtual machine) that contains webserver, point 3 is important – because there’s only one public IP address, so there’s only one port 80 and 443 that’s facing the Internet.

By forwarding port 80 and 443 to a reverse-proxy in a CT, then we’ll be able to forward incoming visitors, by hostname / domain name, to the correct CT/VM.


Modify the following to match your host’s interface name & CT/VM’s internal IP addresses, then copy-paste to terminal :

###### All HTTP/S traffic are forwarded to reverse proxy
iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 80 -j DNAT --to

iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 443 -j DNAT --to

###### SSH ports to each existing CT/VM
iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 22101 -j DNAT --to

iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 22102 -j DNAT --to

iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 22103 -j DNAT --to

iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 22104 -j DNAT --to

Then we save it :

iptables-save > /etc/iptables.rules


Edit /etc/network/interfaces file, find your network interface name that’s facing the Internet (in my case, vmbr0) – then add the pre-up line as follows :

auto vmbr0
pre-up iptables-restore < /etc/iptables.rules


In a CT, install Nginx. Then for each domain, create a configuration file like this, for example: /etc/nginx/sites-available/ :

server {
listen 80;

location / {
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;


To activate it (assuming you’re using Ubuntu) link it to /etc/nginx/sites-enabled/ , then restart Nginx :

ln -s /etc/nginx/sites-available/ /etc/nginx/sites-enabled/

/etc/init.d/nginx restart

note: as noted before, all HTTP/s traffic will have to go through this reverse-proxy. You may wish to tune this Nginx installation accordingly.


It’s very easy with Let’s Encrypt once you’ve done point 3 above. Do the following on the reverse-proxy CT :

sudo apt-get update ; sudo apt-get install -y certbot python3-certbot-nginx

sudo certbot --nginx

sudo /etc/init.d/nginx restart


Installing HTTrack on Ubuntu from Source

Today I needed to have the latest version of HTTrack installed to make a (static) mirror of a website that I managed

After a few attempts, this is how you compile & install HTTrack from source on Ubuntu :

wget ""

mv cserv.php3\?File\=httrack.tar.gz  httrack.tar.gz

tar xzvf httrack.tar.gz

cd httrack-3.49.2/

### the following is the key to a successful install
apt-get install zlib1g-dev libssl-dev build-essential

./configure && make && make install

Cutting a Table out of a mysqldump output file

I was restoring the backup of a MySQL 5.x server into MySQL 8.x server – and found out that it corrupt the MySQL 8.x ‘s mysql table

Which stores the usernames and passwords.

So I had to delete the mysql table from the backup, before trying to restore it again

Turn out it’s pretty easy, just will take some time since it’s a pretty big backup :

# search for beginning of 'mysql' table
cat backup.mysql | grep -n Current Database: `mysql`

# 155604:-- Current Database: `mysql`

# search for ending of 'mysql' table
tail -n +155604 backup.mysql | grep -n "Current Database"

# 1:  -- Current Database: `mysql`
# 916:-- Current Database: `phpmyadmin`

# cut that table out
head -155603 backup.mysql                > new.mysql
tail -n +$(( 155603+916 )) backup.mysql >> new.mysql

# voila !

Crontab runs on different timezone : here’s the fix

A few days ago I got reports that a server is running its cron jobs at strange times. Logged in, and indeed it was. A huge backup was running during peak hours. Saying that it disrupt people’s work is an understatement.

To my surprise, the explanation for this issue can not be found straightaway. Took some googling to find the cause. And even more time to find the correct solution.

So to cut the chase – /etc/localtime was a link to /usr/share/zoneinfo/America/NewYork

Changed it to /usr/share/zoneinfo/Asia/Jakarta – and voila, now the cronjobs are running at the correct times.

Hope it helps

XCTB – X Compression Tool Benchmarker

I deal with a lot of big files at work. While storage capacity is not infinite indeed. So it’s in my interest to keep the file sizes as low as possible.

One way to achieve that is by using compression. Especially when dealing with log files, or database archive, you can save a ton of space with the right compression tool.

But space saving is not the only consideration.

You also need to weighs in other factors. Such as :

  • File type : different tool will compress different type of file differently
  • CPU multi-core capabilities
  • Compression speed
  • Compression size
  • Decompression time

But there are so many great compression tools available in Unix / Linux. It can be really confusing to choose which one to use even for a seasoned expert.

So I created X Compression Tool Benchmarker to help with this.

Features :

  • Test any kind of file : just put the file’s name as the parameter when calling the script. Then it will be tested against all the specified compression tools.
  • Add more compression tool easily : just edit the compressor_list & ext_file variable, and that’s it
  • Fire and forget : just run the script, and forget it. It will run without needing any intervention
  • CSV output : ready to be opened with Libre Office / Excel, and made into graphs in seconds.

Here’s a sample result for a Database archive file (type MySQL dump) :

The bar chart on top of this article is based from this result.

As you can see, currently this script will benchmark the following compression tools automatically : pigz – gzip – bzip2 – pbzip2 – lrzip – rzip – zstd – pixz – plzip – xz

The result, for each different file types, may surprise you ๐Ÿ™‚

For example ; I was surprised to see rzip beat lrzip – because lrzip is supposed to be the enhancement of rzip.

Then I was even more surprised to find out that :

  • I was testing Debian Buster’s version of rzip, which turned out to be pretty old – it does not even have multi-thread/core capability
  • But when I tested the latest version of rzip, which can use all the 16 cores in my server – it turned out to be slower than the old rzip from Debian Buster !
  • No, disk speed is not an issue – I made sure that all the benchmark was run from NVME SSD

So I was grinning at how Debian Buster packaged a very old version of rzip instead of the new one – turned out the joke’s on me : the old rzip perform better than the new one. Even without the multi-core capability.

Also it was amazing to see how really REALLY fast zstd is, while still giving decent compression size. When you absolutely need compression speed, this not so well known compression tool turned out to be the clear winner.

And so on, etc

Yes, indeed I had fun ๐Ÿ™‚

I hope you will too. Enjoy !

UPDATE : My friend , Eko Juniarto, published his results here and have permitted me to publish it here as well – thanks. Very interesting, indeed.

BCA – daftar bank korespondensi di Amerika

Suatu hari saya ditanyakan hal ini (bank korespondensi BCA di Amerika) setelah selesai seminar di Hawaii, untuk mentransfer honorarium saya.

Ternyata info ini tidak ketemu dimana-mana.

Tanya via Call center BCA di 1500888, mereka juga tidak tahu.

Akhirnya ketika istri saya kebetulan ada perlu ke BCA, dia tanyakan sekalian. Dijawab bahwa musti saya sendiri yang datang menanyakan.

Istri saya marah besar ๐Ÿ˜€ hahahaha

Apa logikanya cuma menanya “informasi bank korespondensi BCA” dengan saya musti datang sendiri ke BCA ๐Ÿ˜€ ha ha ha

Kalau karena musti nasabah BCA – istri saya juga nasabah BCA, dia juga punya rekening di BCA.

Akhirnya customer service BCA menyerah, dan memberitahu informasi tsb, hahaha. Ada-ada saja.

Saya lampirkan informasi tsb disini. Maka moga yang membutuhkannya tidak perlu mengalami kekonyolan serupa & terbuang-buang waktunya juga.

NAMA BANK : Bank of New York

NAMA BANK : Bank of America

NAMA BANK : Wells Fargo Bank

NAMA BANK : JP Morgan Chase Bank

NAMA BANK : Citibank

NAMA BANK : Standard Chartered Bank

Instalasi w3af

w3af (Web Application Attack and Audit Framework) adalah software yang bisa Anda gunakan untuk memeriksa keamanan aplikasi / website Anda.

Cara instalasi & penggunaannya sangat mudah, silakan ikuti panduan ini :

sudo apt-get update ; sudo apt-get -y install python-pip git

git clone
cd w3af/
# install semua paket yang diminta, lalu


Maka kini w3af & semua paket software yang dibutuhkannya telah terpasang.

Lalu buat file bernama MyScript.w3af, dengan isi sbb :

(CATATAN : jangan gunakan dulu plugin “redos” – terakhir saya gunakan, plugin redos ini berjalan selama 2 hari dan menghabiskan disk space di server saya. Hati-hati)

# -----------------------------------------------------------------------------------------------------------
# -----------------------------------------------------------------------------------------------------------
#Configure HTTP settings
set timeout 30
#Configure scanner global behaviors
set timeout 20
set max_requests_per_second 100
set max_discovery_time 20
set fuzz_cookies True
set fuzz_form_files True
set fuzz_url_parts True
set fuzz_url_filenames True
#Configure entry point (CRAWLING) scanner
crawl web_spider
crawl config web_spider
set only_forward False
set ignore_regex (?i)(logout|disconnect|signout|exit)+
#Configure vulnerability scanners
##Specify list of AUDIT plugins type to use
audit blind_sqli, buffer_overflow, cors_origin, csrf, eval, file_upload, ldapi, lfi, os_commanding, phishing_vector, response_splitting, sqli, xpath, xss, xst
##Customize behavior of each audit plugin when needed
audit config file_upload
set extensions jsp,php,php2,php3,php4,php5,asp,aspx,pl,cfm,rb,py,sh,ksh,csh,bat,ps,exe
##Specify list of GREP plugins type to use (grep plugin is a type of plugin that can find also vulnerabilities or informations disclosure)
grep analyze_cookies, click_jacking, code_disclosure, cross_domain_js, csp, directory_indexing, dom_xss, error_500, error_pages,
html_comments, objects, path_disclosure, private_ip, strange_headers, strange_http_codes, strange_parameters, strange_reason, url_session, xss_protection_header
##Specify list of INFRASTRUCTURE plugins type to use (infrastructure plugin is a type of plugin that can find informations disclosure)
infrastructure server_header, server_status, domain_dot, dot_net_errors
#Configure target authentication
#Configure reporting in order to generate an HTML report
output console, html_file
output config html_file
set output_file /tmp/W3afReport.html
set verbose False
output config console
set verbose False
#Set target informations, do a cleanup and run the scan
set target
set target_os unix
set target_framework php

Simpan file tersebut, lalu jalankan perintah sbb :

./w3af_console ยญ-s MyScript.w3af

Kini tinggal Anda tunggu sampai selesai, dan setelah itu laporannya bisa dilihat di /tmp/W3afReport.html

Enjoy !

Setup Varnish on Port 80

Sometimes you need to quickly setup Varnish, usually in an emergency (like, your website got featured on Reddit’s frontpage ๐Ÿ˜€ ), to quickly absorb most of the hits hitting your website.

But the webserver is already using port 80.
Now what ?

Pretty easy actually :

  1. Setup Varnish on other port, say, 6081
  2. Run an iptables command : to forward incoming traffic from port 80 to port 6081
  3. Make sure Varnish uses as the backend

Presto – now all the traffic hits Varnish first – which will process them in lightning speed.

Alright, so here’s the gory detail, also available on :

Enjoy !


apt-get update ; apt-get -y install varnish

# Varnish should be already configured to list on port 6081
# if in doubt, check /etc/default/varnish,
# and look for the following line :
# DAEMON_OPTS="-a :6081

# edit varnish config
vi /etc/varnish/default.vcl

# make sure the .port line is set to 80, like this :
# .port = "80";
# then save & exit

# enable Apache's expires & headers module
a2enmod expires
a2enmod headers

# setup caching for static files
# via .htaccess file
echo "Header unset ETag" >> /var/www/.htaccess
echo "FileETag None" >> /var/www/.htaccess
echo "<ifmodule mod_expires.c>" >> /var/www/.htaccess
echo "<filesmatch \"(?i)^.*\\.(ico|flv|jpg|jpeg|png|gif|js|css)$\">" >> /var/www/.htaccess
echo "ExpiresActive On" >> /var/www/.htaccess
echo "ExpiresDefault \"access plus 2 minute\"" >> /var/www/.htaccess
echo "</filesmatch>" >> /var/www/.htaccess
echo "</ifmodule>" >> /var/www/.htaccess

# enable caching in php.ini
vi /etc/php/7.0/apache2/php.ini

# make sure session.cache_limiter = public
# save & exit

# restart Apache
/etc/init.d/apache2 restart

###### now let's start forwarding traffic to Varnish ######

# enable port forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward
vi /etc/sysctl.conf

# add this line at the end of the file :
# net.ipv4.ip_forward = 1

# now here's the command that will actually forward the traffic from port 80 to Varnish
# change eth0 to your computer's network interface name
iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 6081

# make sure this iptables setting will become permanent
apt-get -y install iptables-persistent

WordPress Auto-Backup via SSH

This script will enable you to backup your WordPress websites automatically. Just put it in a crontab / automatic scheduling software somewhere.

Also available on Pastebin :



# 1/ You can do SSH password-less login to the server
# How :
# 2/ You have created a correct ~/.my.cnf file
# How :

# ====== START BACKUP ============

today=`date +%A`

# backup database
ssh $wordpress_server "mysqldump -h $mysql_server $mysql_database > $wordpress_location/db-$today.mysql"
ssh $wordpress_server "gzip $wordpress_location/db-$today.mysql"

# download everything
rsync -avuz --delete $wordpress_server:$wordpress_location/* $backup_location/

# delete database backup
# so no one can download it via the website
ssh $wordpress_server "rm $wordpress_location/db-$today.mysql.gz"

# done !

Chuck Norris Facts – Science Version

:: Chuck Norris counted to infinity… Twice.

Chuck Norris knows the last digit of pi.

According to Einstein's theory of relativity, Chuck Norris can actually roundhouse kick you yesterday.

Chuck Norris roundhouse kicks don't really kill people. They wipe out their entire existence from the space-time continuum.

Human cloning is outlawed because if Chuck Norris were cloned, then it would be possible for a Chuck Norris roundhouse kick to meet another chuck Norris roundhouse kick. Physicists theorize that this contact would end the universe.

It is scientifically impossible for Chuck Norris to have had a mortal father. The most popular theory is that he went back in time and fathered himself.

Chuck Norris destroyed the periodic table, because Chuck Norris only recognizes the element of surprise.

It is believed dinosaurs are extinct due to a giant meteor. That's true if you want to call Chuck Norris a giant meteor.

There is no theory of evolution. Just a list of animals Chuck Norris allows to live.

Chuck Norrisโ€™ roundhouse kick is so powerful, it can be seen from outer space by the naked eye.

Chuck Norris has already been to Mars; that's why there are no signs of life there.

Scientists have estimated that the energy given off during the Big Bang is roughly equal to 1CNRhK (Chuck Norris Roundhouse Kick)

Chuck Norris can divide by zero.

Thousands of years ago Chuck Norris came across a bear. It was so terrified that it fled north into the arctic. It was also so terrified that all of its decendents now have white hair.

The First Law of Thermodynamics states that energy can neither be created nor destroyed… unless it meets Chuck Norris.

The chemical formula for the highly toxic cyanide ion is CN-. These are also Chuck Norris' initials. This is not a coincidence.

Aliens DO indeed exist. They just know better than to visit a planet that Chuck Norris is on.

We live in an expanding universe. All of it is trying to get away from Chuck Norris.

The Manhattan Project was not intended to create nuclear weapons, it was meant to recreate the destructive power in a Chuck Norris Roundhouse Kick. They didn't even come close.

Chuck Norris' pulse is measured on the richter scale.

Chuck Norris can sneeze with his eyes open.

Earth's emergency defence plan in case of alien invasion is Chuck Norris.

Chuck Norris can split the atom. With his bare hands.

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HTI – Hizbut Tahrir Indonesia, Mengajak Untuk Memberontak

:: Di sebuah grup Whatsapp pernah ada kawan yang menyatakan bahwa HTI adalah kelompok pemberontak. Nampaknya ybs mendapat kesimpulan tsb antara lain dari artikel terlampir ini :

Diserukan kepada para jenderal yang beragama Islam, untuk melakukan kudeta (mengambil kekuasaan) – dan lalu menyerahkannya pada HTI.

Dan kemudian ditebarkan janji-janji manis, bahwa Khilafah ala HTI akan menyelesaikan semua masalah yang sudah ada selama bertahun-tahun dengan mudah saja.

Bahkan dengan #sombong menyatakan, bahwa akan mengalahkan Israel hanya dalam waktu 1 hari.

Walaupun fakta sudah membuktikan, bahwa bahkan berbagai peperangan yang dilakukan oleh Rasulullah saw sekalipun kadang butuh waktu berhari-hari. Apa mereka mengira mereka ini lebih baik daripada utusan Allah ?

Sifat pemberontak seperti ini bertentangan dengan sangat banyak perintah Nabi saw, untuk taat kepada pemimpin.

Ini adalah antara lain sifat kaum Khawarij, seperti yang dipaparkan oleh imam Hasan al Bashri :

Seorang lelaki dari kaum khawarij mendatangi Hasan Al Bashri rahimahullah, si khawarij ini bertanya kepada beliau,

"Apa pendapatmu mengenai khawarij?"

Hasan Al Bashri menjawab,
"Mereka adalah para pencari dunia."

Lelaki itu berkata,
"Mengapa engkau berkata demikian, tidakkah kau tahu bahwa salah seorang di antara mereka itu rela berjalan (untuk memerangi penguasa yang tidak adil) dengan tombaknya hingga patah tombak tersebut, ia bahkan pergi meninggalkan keluarga dan anaknya."

Hasan Al Bashri berkata,
"Coba jawab pertanyaanku mengenai penguasa ini, adakah dia melarangmu untuk sholat, menunaikan zakat, haji dan umrah?"

Lelaki itu menjawab,

Hasan Al Bashri kemudian menjawab,
"Aku melihat bahwa ia menahan dunia darimu, sehingga kau pun memeranginya karena menginginkan dunia tersebut."

ุงู„ุจุตุงุฆุฑ ูˆ ุงู„ุฏุฎุงุฆุฑ ู„ุฃุจูŠ ุญูŠุงู†

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I/O Load Monitoring

:: A few days ago a client of mine complained about slowdown on his website. I checked his server, and later noticed that the server seemed to be burdened with heavy I/O operations.

When checked with tools such as "top", the row showing "%wa" (meaning: I/O wait) was very high. Normally < 10%, it was ranging from 50% up to 98% instead.

This is a very alarming information. Because the server is using SSD disks ๐Ÿ™‚ so its I/O (input/output) should be #really fast. Not bogged down like this.

I checked the daemons (server software) such as Apache, MySQL, Varnish, etc – and they were all idling. None were busy.

So the I/O load came from somewhere else. Probably from the hypervisor (physical server) itself. Which means it's a possible hardware problem.

Because the datacenter has concluded that it was not a "noisy neighbour" – another VM (virtual machine) in the same physical server that's hogging all the I/O resources. Pretty much all of them were idling, just like mine.

However I'll need some data to convince the datacenter to do hardware check on its SSD storage cluster. So I wrote this little bash script :

The script logs server's I/O status into a CSV (Excel) format. So it can be very easily graphed later.

Using iostat tool, it probed the server's current I/O load.
Then the script is executed every minute, by running in as a cronjob.

You may notice that iostat is executed with "-d 1 3" parameter. Which means "run 3 times, with 1 second delay in between"

This is because iostat's first run always cause a spike in I/O load ๐Ÿ™‚ so the numbers would be inaccurate. I noticed the numbers tend to stabilize after the 3rd run, so I set it up that way.

Of course, you can very easily modify this script to monitor something totally different ๐Ÿ™‚ just change the iostat / head / tail / cut part to something else – voila.

Attached is a graph created from one of the log. The X axis is timestamp, in military format (24 hours)

I submitted the logs to the datacenter.

It convinced them to do checks on the storage cluster – and voila, they found some degraded disks in that cluster ๐Ÿ™‚

Damaged disks replaced, storage cluster rebuilt – and everyone lives happily ever after ? ๐Ÿ™‚ Fingers crossed. Happy ending !

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Kita Bisa Lawan Hoax

:: Gambar terlampir ini memberikan harapan ๐Ÿ™‚ bukti bahwa kita #bisa melawan hoax. Lingkaran di sebelah kiri menampilkan hanya 2 titik oranye, para aktivis anti hoax – namun, sudah cukup untuk nyaris melenyapkan titik ungu; yaitu berita hoax ๐Ÿ˜€

Ini adalah hasil penelitian Professor Filippo Menczer dan koleganya. Sangat relevan dengan situasi di Indonesia, yaitu dimana mayoritas hoax menyebar melalui komunitas-komunitas tertutup di BBM atau Whatsapp.

Tanpa aktivis anti hoax, maka akan terjadi lingkaran di sebelah kanan – virus hoax bebas merajalela.

Mari bersama-sama kita BISA melawan hoax. (y)

Sumber :

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Happy Ending

:: Di tahun 2013, dibahas tentang perburuan sebuah penyakit misterius, yang membunuhi anak-anak di India sejak 1995 ๐Ÿ™ setiap bulan Mei :O :O Bagaimana mereka mati-matian bekerja keras untuk mengungkap sumber penyakit yang misterius ini.

Di tahun 2017, akhirnya muncul kabar gembira : mereka sudah berhasil menemukan penyebabnya ๐Ÿ˜€ yaitu, buah leci (lychee) :O :O :O

Siapa sangka ?? ๐Ÿ™‚ ternyata buah leci bisa membunuh anak kecil ๐Ÿ™

Ternyata ada 3 kondisi yang kebetulan muncul di setiap bulan Mei :

(1) Pohon leci berbuah, dan dimakan oleh anak-anak

(2) Anak-anak banyak yang kekurangan gizi : salah satu dampaknya adalah kadar gula darah yang rendah.

(3) Buah leci mengandung racun Hypoglycin & MCPG : keduanya membuat tubuh sulit mengubah glukosa/gula menjadi gula darah.

Poin 2 ditambah poin 3, membuat sebagian anak-anak yang memakan buah leci menjadi drop kadar gula darahnya sampai ke tingkat yang fatal ๐Ÿ™

Masalah ini jadi kini bisa diatasi dengan mengajarkan 2 hal kepada para orang tua :

(1) Anak-anak harus mendapat asupan gizi yang cukup

(2) Batasi konsumsi buah leci oleh anak-anak

Alhamdulillah, kini jumlah kasus ini jadi drop dengan sangat signifikan ๐Ÿ˜€ <3

Berkat metode investigasi yang ilmiah, bukan cuma berdasarkan perasaan, maka misteri yang sudah ada selama 20 tahun ini akhirnya jadi bisa dipecahkan dalam waktu sekitar 2 tahun.

Salut kepada para pahlawan yang telah menyelamatkan nyawa anak-anak ini ๐Ÿ™‚ semoga kita bisa tiru teladan mereka (y)

Dangerous Fruit: Mystery of Deadly Outbreaks in India Is Solved –

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