Mohamad Zulfahmy, Author at Mohamad Zulfahmy

OpenVPN CentOS, Ubuntu & Debian Install Script

by Mohamad Zulfahmy | 04/04/2018 | Scripts

#!/bin/bash
# OpenVPN road warrior installer for Debian, Ubuntu and CentOS

# This script will work on Debian, Ubuntu, CentOS and probably other distros
# of the same families, although no support is offered for them. It isn't
# bulletproof but it will probably work if you simply want to setup a VPN on
# your Debian/Ubuntu/CentOS box. It has been designed to be as unobtrusive and
# universal as possible.


# Detect Debian users running the script with "sh" instead of bash
if readlink /proc/$$/exe | grep -qs "dash"; then
	echo "This script needs to be run with bash, not sh"
	exit 1
fi

if [[ "$EUID" -ne 0 ]]; then
	echo "Sorry, you need to run this as root"
	exit 2
fi

if [[ ! -e /dev/net/tun ]]; then
	echo "The TUN device is not available
You need to enable TUN before running this script"
	exit 3
fi

if grep -qs "CentOS release 5" "/etc/redhat-release"; then
	echo "CentOS 5 is too old and not supported"
	exit 4
fi
if [[ -e /etc/debian_version ]]; then
	OS=debian
	GROUPNAME=nogroup
	RCLOCAL='/etc/rc.local'
elif [[ -e /etc/centos-release || -e /etc/redhat-release ]]; then
	OS=centos
	GROUPNAME=nobody
	RCLOCAL='/etc/rc.d/rc.local'
else
	echo "Looks like you aren't running this installer on Debian, Ubuntu or CentOS"
	exit 5
fi

newclient () {
	# Generates the custom client.ovpn
	cp /etc/openvpn/client-common.txt ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	cat /etc/openvpn/easy-rsa/pki/ca.crt >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	cat /etc/openvpn/easy-rsa/pki/issued/$1.crt >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	cat /etc/openvpn/easy-rsa/pki/private/$1.key >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
	cat /etc/openvpn/ta.key >> ~/$1.ovpn
	echo "" >> ~/$1.ovpn
}

# Try to get our IP from the system and fallback to the Internet.
# I do this to make the script compatible with NATed servers (lowendspirit.com)
# and to avoid getting an IPv6.
IP=$(ip addr | grep 'inet' | grep -v inet6 | grep -vE '127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | head -1)
if [[ "$IP" = "" ]]; then
		IP=$(wget -4qO- "http://whatismyip.akamai.com/")
fi

if [[ -e /etc/openvpn/server.conf ]]; then
	while :
	do
	clear
		echo "Looks like OpenVPN is already installed"
		echo ""
		echo "What do you want to do?"
		echo "   1) Add a new user"
		echo "   2) Revoke an existing user"
		echo "   3) Remove OpenVPN"
		echo "   4) Exit"
		read -p "Select an option [1-4]: " option
		case $option in
			1) 
			echo ""
			echo "Tell me a name for the client certificate"
			echo "Please, use one word only, no special characters"
			read -p "Client name: " -e -i client CLIENT
			cd /etc/openvpn/easy-rsa/
			./easyrsa build-client-full $CLIENT nopass
			# Generates the custom client.ovpn
			newclient "$CLIENT"
			echo ""
			echo "Client $CLIENT added, configuration is available at" ~/"$CLIENT.ovpn"
			exit
			;;
			2)
			# This option could be documented a bit better and maybe even be simplimplified
			# ...but what can I say, I want some sleep too
			NUMBEROFCLIENTS=$(tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep -c "^V")
			if [[ "$NUMBEROFCLIENTS" = '0' ]]; then
				echo ""
				echo "You have no existing clients!"
				exit 6
			fi
			echo ""
			echo "Select the existing client certificate you want to revoke"
			tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | nl -s ') '
			if [[ "$NUMBEROFCLIENTS" = '1' ]]; then
				read -p "Select one client [1]: " CLIENTNUMBER
			else
				read -p "Select one client [1-$NUMBEROFCLIENTS]: " CLIENTNUMBER
			fi
			CLIENT=$(tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | sed -n "$CLIENTNUMBER"p)
			cd /etc/openvpn/easy-rsa/
			./easyrsa --batch revoke $CLIENT
			EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
			rm -rf pki/reqs/$CLIENT.req
			rm -rf pki/private/$CLIENT.key
			rm -rf pki/issued/$CLIENT.crt
			rm -rf /etc/openvpn/crl.pem
			cp /etc/openvpn/easy-rsa/pki/crl.pem /etc/openvpn/crl.pem
			# CRL is read with each client connection, when OpenVPN is dropped to nobody
			chown nobody:$GROUPNAME /etc/openvpn/crl.pem
			echo ""
			echo "Certificate for client $CLIENT revoked"
			exit
			;;
			3) 
			echo ""
			read -p "Do you really want to remove OpenVPN? [y/n]: " -e -i n REMOVE
			if [[ "$REMOVE" = 'y' ]]; then
				PORT=$(grep '^port ' /etc/openvpn/server.conf | cut -d " " -f 2)
				PROTOCOL=$(grep '^proto ' /etc/openvpn/server.conf | cut -d " " -f 2)
				if pgrep firewalld; then
					IP=$(firewall-cmd --direct --get-rules ipv4 nat POSTROUTING | grep '\-s 10.8.0.0/24 '"'"'!'"'"' -d 10.8.0.0/24 -j SNAT --to ' | cut -d " " -f 10)
					# Using both permanent and not permanent rules to avoid a firewalld reload.
					firewall-cmd --zone=public --remove-port=$PORT/$PROTOCOL
					firewall-cmd --zone=trusted --remove-source=10.8.0.0/24
					firewall-cmd --permanent --zone=public --remove-port=$PORT/$PROTOCOL
					firewall-cmd --permanent --zone=trusted --remove-source=10.8.0.0/24
					firewall-cmd --direct --remove-rule ipv4 nat POSTROUTING 0 -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
					firewall-cmd --permanent --direct --remove-rule ipv4 nat POSTROUTING 0 -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
				else
					IP=$(grep 'iptables -t nat -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to ' $RCLOCAL | cut -d " " -f 14)
					iptables -t nat -D POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
					sed -i '/iptables -t nat -A POSTROUTING -s 10.8.0.0\/24 ! -d 10.8.0.0\/24 -j SNAT --to /d' $RCLOCAL
					if iptables -L -n | grep -qE '^ACCEPT'; then
						iptables -D INPUT -p $PROTOCOL --dport $PORT -j ACCEPT
						iptables -D FORWARD -s 10.8.0.0/24 -j ACCEPT
						iptables -D FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
						sed -i "/iptables -I INPUT -p $PROTOCOL --dport $PORT -j ACCEPT/d" $RCLOCAL
						sed -i "/iptables -I FORWARD -s 10.8.0.0\/24 -j ACCEPT/d" $RCLOCAL
						sed -i "/iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT/d" $RCLOCAL
					fi
				fi
				if hash sestatus 2>/dev/null; then
					if sestatus | grep "Current mode" | grep -qs "enforcing"; then
						if [[ "$PORT" != '1194' || "$PROTOCOL" = 'tcp' ]]; then
							semanage port -d -t openvpn_port_t -p $PROTOCOL $PORT
						fi
					fi
				fi
				if [[ "$OS" = 'debian' ]]; then
					apt-get remove --purge -y openvpn
				else
					yum remove openvpn -y
				fi
				rm -rf /etc/openvpn
				echo ""
				echo "OpenVPN removed!"
			else
				echo ""
				echo "Removal aborted!"
			fi
			exit
			;;
			4) exit;;
		esac
	done
else
	clear
	echo 'Welcome to this quick OpenVPN "road warrior" installer'
	echo ""
	# OpenVPN setup and first user creation
	echo "I need to ask you a few questions before starting the setup"
	echo "You can leave the default options and just press enter if you are ok with them"
	echo ""
	echo "First I need to know the IPv4 address of the network interface you want OpenVPN"
	echo "listening to."
	read -p "IP address: " -e -i $IP IP
	echo ""
	echo "Which protocol do you want for OpenVPN connections?"
	echo "   1) UDP (recommended)"
	echo "   2) TCP"
	read -p "Protocol [1-2]: " -e -i 1 PROTOCOL
	case $PROTOCOL in
		1) 
		PROTOCOL=udp
		;;
		2) 
		PROTOCOL=tcp
		;;
	esac
	echo ""
	echo "What port do you want OpenVPN listening to?"
	read -p "Port: " -e -i 1194 PORT
	echo ""
	echo "Which DNS do you want to use with the VPN?"
	echo "   1) Current system resolvers"
	echo "   2) Google"
	echo "   3) OpenDNS"
	echo "   4) NTT"
	echo "   5) Hurricane Electric"
	echo "   6) Verisign"
	read -p "DNS [1-6]: " -e -i 1 DNS
	echo ""
	echo "Finally, tell me your name for the client certificate"
	echo "Please, use one word only, no special characters"
	read -p "Client name: " -e -i client CLIENT
	echo ""
	echo "Okay, that was all I needed. We are ready to setup your OpenVPN server now"
	read -n1 -r -p "Press any key to continue..."
	if [[ "$OS" = 'debian' ]]; then
		apt-get update
		apt-get install openvpn iptables openssl ca-certificates -y
	else
		# Else, the distro is CentOS
		yum install epel-release -y
		yum install openvpn iptables openssl wget ca-certificates -y
	fi
	# An old version of easy-rsa was available by default in some openvpn packages
	if [[ -d /etc/openvpn/easy-rsa/ ]]; then
		rm -rf /etc/openvpn/easy-rsa/
	fi
	# Get easy-rsa
	wget -O ~/EasyRSA-3.0.3.tgz "https://github.com/OpenVPN/easy-rsa/releases/download/v3.0.3/EasyRSA-3.0.3.tgz"
	tar xzf ~/EasyRSA-3.0.3.tgz -C ~/
	# Temporal fix for issue #353, which is caused by OpenVPN/easy-rsa#135
	# Will be removed as soon as a new release of easy-rsa is available
	sed -i 's/\[\[/\[/g;s/\]\]/\]/g;s/==/=/g' ~/EasyRSA-3.0.3/easyrsa
	mv ~/EasyRSA-3.0.3/ /etc/openvpn/
	mv /etc/openvpn/EasyRSA-3.0.3/ /etc/openvpn/easy-rsa/
	chown -R root:root /etc/openvpn/easy-rsa/
	rm -rf ~/EasyRSA-3.0.3.tgz
	cd /etc/openvpn/easy-rsa/
	# Create the PKI, set up the CA, the DH params and the server + client certificates
	./easyrsa init-pki
	./easyrsa --batch build-ca nopass
	./easyrsa gen-dh
	./easyrsa build-server-full server nopass
	./easyrsa build-client-full $CLIENT nopass
	EASYRSA_CRL_DAYS=3650 ./easyrsa gen-crl
	# Move the stuff we need
	cp pki/ca.crt pki/private/ca.key pki/dh.pem pki/issued/server.crt pki/private/server.key pki/crl.pem /etc/openvpn
	# CRL is read with each client connection, when OpenVPN is dropped to nobody
	chown nobody:$GROUPNAME /etc/openvpn/crl.pem
	# Generate key for tls-auth
	openvpn --genkey --secret /etc/openvpn/ta.key
	# Generate server.conf
	echo "port $PORT
proto $PROTOCOL
dev tun
sndbuf 0
rcvbuf 0
ca ca.crt
cert server.crt
key server.key
dh dh.pem
auth SHA512
tls-auth ta.key 0
topology subnet
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt" > /etc/openvpn/server.conf
	echo 'push "redirect-gateway def1 bypass-dhcp"' >> /etc/openvpn/server.conf
	# DNS
	case $DNS in
		1) 
		# Obtain the resolvers from resolv.conf and use them for OpenVPN
		grep -v '#' /etc/resolv.conf | grep 'nameserver' | grep -E -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | while read line; do
			echo "push \"dhcp-option DNS $line\"" >> /etc/openvpn/server.conf
		done
		;;
		2) 
		echo 'push "dhcp-option DNS 8.8.8.8"' >> /etc/openvpn/server.conf
		echo 'push "dhcp-option DNS 8.8.4.4"' >> /etc/openvpn/server.conf
		;;
		3)
		echo 'push "dhcp-option DNS 208.67.222.222"' >> /etc/openvpn/server.conf
		echo 'push "dhcp-option DNS 208.67.220.220"' >> /etc/openvpn/server.conf
		;;
		4) 
		echo 'push "dhcp-option DNS 129.250.35.250"' >> /etc/openvpn/server.conf
		echo 'push "dhcp-option DNS 129.250.35.251"' >> /etc/openvpn/server.conf
		;;
		5) 
		echo 'push "dhcp-option DNS 74.82.42.42"' >> /etc/openvpn/server.conf
		;;
		6) 
		echo 'push "dhcp-option DNS 64.6.64.6"' >> /etc/openvpn/server.conf
		echo 'push "dhcp-option DNS 64.6.65.6"' >> /etc/openvpn/server.conf
		;;
	esac
	echo "keepalive 10 120
cipher AES-256-CBC
comp-lzo
user nobody
group $GROUPNAME
persist-key
persist-tun
status openvpn-status.log
verb 3
crl-verify crl.pem" >> /etc/openvpn/server.conf
	# Enable net.ipv4.ip_forward for the system
	sed -i '/\/c\net.ipv4.ip_forward=1' /etc/sysctl.conf
	if ! grep -q "\" /etc/sysctl.conf; then
		echo 'net.ipv4.ip_forward=1' >> /etc/sysctl.conf
	fi
	# Avoid an unneeded reboot
	echo 1 > /proc/sys/net/ipv4/ip_forward
	if pgrep firewalld; then
		# Using both permanent and not permanent rules to avoid a firewalld
		# reload.
		# We don't use --add-service=openvpn because that would only work with
		# the default port and protocol.
		firewall-cmd --zone=public --add-port=$PORT/$PROTOCOL
		firewall-cmd --zone=trusted --add-source=10.8.0.0/24
		firewall-cmd --permanent --zone=public --add-port=$PORT/$PROTOCOL
		firewall-cmd --permanent --zone=trusted --add-source=10.8.0.0/24
		# Set NAT for the VPN subnet
		firewall-cmd --direct --add-rule ipv4 nat POSTROUTING 0 -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
		firewall-cmd --permanent --direct --add-rule ipv4 nat POSTROUTING 0 -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
	else
		# Needed to use rc.local with some systemd distros
		if [[ "$OS" = 'debian' && ! -e $RCLOCAL ]]; then
			echo '#!/bin/sh -e
exit 0' > $RCLOCAL
		fi
		chmod +x $RCLOCAL
		# Set NAT for the VPN subnet
		iptables -t nat -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP
		sed -i "1 a\iptables -t nat -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to $IP" $RCLOCAL
		if iptables -L -n | grep -qE '^(REJECT|DROP)'; then
			# If iptables has at least one REJECT rule, we asume this is needed.
			# Not the best approach but I can't think of other and this shouldn't
			# cause problems.
			iptables -I INPUT -p $PROTOCOL --dport $PORT -j ACCEPT
			iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT
			iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
			sed -i "1 a\iptables -I INPUT -p $PROTOCOL --dport $PORT -j ACCEPT" $RCLOCAL
			sed -i "1 a\iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT" $RCLOCAL
			sed -i "1 a\iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT" $RCLOCAL
		fi
	fi
	# If SELinux is enabled and a custom port or TCP was selected, we need this
	if hash sestatus 2>/dev/null; then
		if sestatus | grep "Current mode" | grep -qs "enforcing"; then
			if [[ "$PORT" != '1194' || "$PROTOCOL" = 'tcp' ]]; then
				# semanage isn't available in CentOS 6 by default
				if ! hash semanage 2>/dev/null; then
					yum install policycoreutils-python -y
				fi
				semanage port -a -t openvpn_port_t -p $PROTOCOL $PORT
			fi
		fi
	fi
	# And finally, restart OpenVPN
	if [[ "$OS" = 'debian' ]]; then
		# Little hack to check for systemd
		if pgrep systemd-journal; then
			systemctl restart [email protected]
		else
			/etc/init.d/openvpn restart
		fi
	else
		if pgrep systemd-journal; then
			systemctl restart [email protected]
			systemctl enable [email protected]
		else
			service openvpn restart
			chkconfig openvpn on
		fi
	fi
	# Try to detect a NATed connection and ask about it to potential LowEndSpirit users
	EXTERNALIP=$(wget -4qO- "http://whatismyip.akamai.com/")
	if [[ "$IP" != "$EXTERNALIP" ]]; then
		echo ""
		echo "Looks like your server is behind a NAT!"
		echo ""
		echo "If your server is NATed (e.g. LowEndSpirit), I need to know the external IP"
		echo "If that's not the case, just ignore this and leave the next field blank"
		read -p "External IP: " -e USEREXTERNALIP
		if [[ "$USEREXTERNALIP" != "" ]]; then
			IP=$USEREXTERNALIP
		fi
	fi
	# client-common.txt is created so we have a template to add further users later
	echo "client
dev tun
proto $PROTOCOL
sndbuf 0
rcvbuf 0
remote $IP $PORT
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
auth SHA512
cipher AES-256-CBC
comp-lzo
setenv opt block-outside-dns
key-direction 1
verb 3" > /etc/openvpn/client-common.txt
	# Generates the custom client.ovpn
	newclient "$CLIENT"
	echo ""
	echo "Finished!"
	echo ""
	echo "Your client configuration is available at" ~/"$CLIENT.ovpn"
	echo "If you want to add more clients, you simply need to run this script again!"
fi

Flash Factory Asus Router (Broadcom) using TFTP

by Mohamad Zulfahmy | 03/04/2018 | Scripts

Push reset button and power on the device. Hold the reset button for 5-10 seconds.

Set up static IP using this range

IP : 192.168.1.2-30
Netmask : 255.255.255.0
Gateway : 192.168.1.1

Open up terminal and run this command

tftp
> connect 192.168.1.1
> verbose
> status
> put firmwarename.trx

Find Email Spam Script On Cpanel Servers

by Mohamad Zulfahmy | 02/04/2018 | Linux

Sometimes, hackers like to upload malicious script inside compromised website to sending out spam. On Cpanel you can check and identify where the spam script is located using the below command.

grep cwd /var/log/exim_mainlog | grep -v /var/spool | awk -F"cwd=" '{print $2}' | awk '{print $1}' | sort | uniq -c | sort -n

To clear out exim queue, simply run

exim -bp | grep frozen | awk {'print $3'} | xargs exim -Mrm

Lock Down SSH – Restrict certain IP to SSH

by Mohamad Zulfahmy | 01/04/2018 | Scripts

Save as sshlockdown.sh

chmod +x sshlockdown.sh

./sshlockdown.sh

##########################
# LOCK DOWN
##########################
SSHPORT=22

for IP in 111.111.111.111 222.222.222.222 333.333.333.333 444.444.444.444/27 ; do
/sbin/iptables -A INPUT -p tcp -s $IP –dport $SSHPORT -j ACCEPT
/sbin/iptables -A OUTPUT -p tcp -d $IP –sport $SSHPORT -j ACCEPT
done
iptables -A INPUT -p tcp –dport $SSHPORT -j DROP
iptables -A OUTPUT -p tcp –sport $SSHPORT -j DROP

#####################

Clear Directadmin Email Per User Limit

by Mohamad Zulfahmy | 28/03/2018 | Linux

You can clear the per user limit logging in to ssh

echo ""> /etc/virtual/domain.com/usage/info