*** Centos 7.15 Configuration to make a persistent bootable USB***

a) Configure IPv4: ifconfig
b) Configure DNS: 172.25.3.50, 172.25.3.55, 8.8.8.8, 8.8.4.4
c) Configure global proxy: http://proxyti.academic.mixcoac.upmx.mx:8080
d) Configure user proxy: vim ~/.bash_profile ; source ~/.bash_profile 
    export http_proxy=http://proxyti.academic.mixcoac.upmx.mx:8080
    export https_proxy=$http_proxy
    export ftp_proxy=$http_proxy
    export rsync_proxy=$http_proxy
    export no_proxy="localhost,127.0.0.1,localaddress,.localdomain.com,.upmx.mx,.up.edu.mx"
e) Configure Yum proxy settings: sudo vim /etc/yum.conf
   [main]
    proxy=http://proxyti.academic.mixcoac.upmx.mx:8080
f) Configure wget proxy settings: sudo vim /etc/wgetrc
    http_proxy = http://proxyti.academic.mixcoac.upmx.mx:8080/
    https_proxy = http://proxyti.academic.mixcoac.upmx.mx:8080/
    ftp_proxy = http://proxyti.academic.mixcoac.upmx.mx:8080/
    use_proxy = on
g) Install epel-release - Extra Packages for Enterprise Linux repository 
    sudo yum install epel-release
h) Install IUS Community Project repository (optional)
    wget https://dl.iuscommunity.org/pub/ius/stable/CentOS/7/x86_64/ius-release-1.0-14.ius.centos7.noarch.rpm
    sudo rpm -Uvh ius-release*.rpm
    sudo yum install yum-plugin-replace
    * Example to replace stock php with IUS php v5.3
    sudo yum replace php --replace-with php53
i) Install
    wget http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-1.el7.nux.noarch.rpm
    wget http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro
    sudo rpm --import RPM-GPG-KEY-nux.ro
    sudo rpm -Uvh nux-dextop-release-0-1.el7.nux.noarch.rpm
j) Install tools for creating a bootable pendrive
    sudo yum -y install syslinux syslinux-extlinux livecd-tools

sudo livecd-iso-to-disk --format --efi --unencrypted-home --swap-size-mb 512 --overlay-size-mb 4095 --home-size-mb 3072 /dev/sr0 /dev/sdb1