openwrt set wan with random mac

uci set network.wan.macaddr=$(hexdump -n6 -e '6/1 ":%02X"' /dev/urandom | cut -f2- -d ":")
uci commit

Xubuntu abnt2 keyboard

Session and startup -> add ->

setxkbmap -model pc105 -layout br -variant abnt2

phpMyAdmin - Error | The mbstring extension is missing. Ubuntu-16.04

Try using:

sudo apt-get install php-gettext
sudo phpenmod mcrypt 
sudo phpenmod mbstring 
sudo service apache2 restart

Chromium not starting as root in Debian

Problem:

root@debian:~# chromium
[1:1:0614/091456:FATAL:sandbox_linux.cc(178)] Check failed: sandbox::Credentials::MoveToNewUserNS(). 
#0 0x0000b0587b0d 
#1 0x0000b05a01c0 
#2 0x0000b4c6cf33 
#3 0x0000b34d75dc 

Solution:

root@debian:~# chromium --user-data-dir=/root/chromium --no-sandbox 

Debian / Ubuntu: build custom package with checkinstall

Using checkinstall is easy to manage/remove custom packages.

apt-get -y install checkinstall

wget custom-package.tar.gz
tar xfvz custom-package.tar.gz
cd custom-package
./configure
make
checkinstall make install

# list package contents
dpkg -L custom-package

# remove package
dpkg -r custom-package

Force all network traffic pass through OpenVPN tunnel

# Flush all rules
iptables -F

# Let's change the policy to DROP.
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP

# Allow basic INPUT traffic.
iptables -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 8 -m conntrack --ctstate NEW -j ACCEPT

# Allow basic OUTPUT traffic.
iptables -A OUTPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
iptables -A OUTPUT -p icmp -j ACCEPT

# Allow traffic to the OpenVPN server, DNS and via the tunnel.
iptables -A OUTPUT -o tun+ -j ACCEPT
iptables -A OUTPUT -p udp -m udp -d 8.8.8.8 --dport 53 -j ACCEPT
iptables -A OUTPUT -p udp -m udp -d 8.8.4.4 --dport 53 -j ACCEPT
iptables -A OUTPUT -p udp -m udp -d vpn.server.example.com --dport 1194 -j ACCEPT

# Reject everything else.
iptables -A INPUT -m conntrack --ctstate INVALID -j DROP
iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable
iptables -A FORWARD -j REJECT --reject-with icmp-port-unreachable
iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable

Write new system image using bmaptool (beaglebone)

#install
sudo apt-get -y install bmap-tools

# download image and bmap file
wget https://debian.beagleboard.org/images/bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.img.xz
wget https://debian.beagleboard.org/images/bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.bmap

 #write system image
bmaptool copy bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.img.xz /dev/sdb


#results
bmaptool: info: discovered bmap file 'bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.bmap'
bmaptool: info: block map format version 2.0
bmaptool: info: 870400 blocks of size 4096 (3.3 GiB), mapped 743361 blocks (2.8 GiB or 85.4%)
bmaptool: info: copying image 'bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.img.xz' to block device '/dev/sdb' using bmap file 'bone-debian-8.3-lxqt-4gb-armhf-2016-01-24-4gb.bmap'
bmaptool: info: 1% copied

Google Cloud Plataform - Compute engine - comand line examples

#list machine types
gcloud compute machine-types list

#list created instances
gcloud compute instances list

#create a redhat-6 instance with default machine type
gcloud compute instances create example-instance --image rhel-6 --zone us-central1-a

#delete redhat-6 instance
gcloud compute instances delete example-instance --zone us-central1-a

#create a ubuntu 15.10 instance with f1-micro machine type
gcloud compute instances create ubuntu1510-f1micro --image ubuntu-15-10 --zone us-central1-a --machine-type f1-micro

#create a ubuntu 15.10 instance with f1-micro machine type with HTTP/HTTPS enabled
gcloud compute instances create ubuntu1510-f1micro --image ubuntu-15-10 --zone us-central1-a --machine-type f1-micro  --tags http-server,https-server

#stop ubuntu 15.10 instance
gcloud compute instances stop ubuntu1510-f1micro  --zone us-central1-a

#start ubuntu 15.10 instance
gcloud compute instances start ubuntu1510-f1micro  --zone us-central1-a

#hardware reboot ubuntu 15.10 instance
gcloud compute instances reset ubuntu1510-f1micro  --zone us-central1-a


#ubuntu 15.10 instance change machine type to n1-standard-1
gcloud compute instances set-machine-type ubuntu1510-f1micro --machine-type n1-standard-1 --zone us-central1-a

#ubuntu 15.10 instance change machine type to g1-small
gcloud compute instances set-machine-type ubuntu1510-f1micro --machine-type g1-small  --zone us-central1-a

#ubuntu 15.10 instance change machine type to f1-micro
gcloud compute instances set-machine-type ubuntu1510-f1micro --machine-type f1-micro  --zone us-central1-a

#ubuntu 15.10 instance enable HTTP/HTTPS access
gcloud compute instances add-tags ubuntu1510-f1micro --zone us-central1-a --tags http-server,https-server

Ubuntu kernel Rebuild

# Get source

apt-get source linux-image-$(uname -r)

# Get tools

apt-get build-dep linux-image-$(uname -r)

# Copy current config

cp -v /boot/config-$(uname -r)   .config

# Customize config

make menuconfig

# parallel build

make -j

# Install kernel modules first (~260MB with debug symbols stripped)

make INSTALL_MOD_STRIP=1 modules_install

# Install kernel image (~6MB)

make install

# Reboot

References:

https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel

watchdog script for openwrt

Make a multi-resolution favicon.ico from a source image, using ImageMagick

convert favicon.png -define icon:auto-resize=64,48,32,16 favicon.ico