Implementación y configuración de OpenVPN [Debian9]

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Qué es OpenVPN?

OpenVPN es una herramienta de conectividad basada en software libre: SSL (Secure Sockets Layer), VPN Virtual Private Network (red virtual privada). OpenVPN ofrece conectividad punto-a-punto con validación jerárquica de usuarios y host conectados remotamente. Resulta una muy buena opción en tecnologías Wi-Fi (redes inalámbricas IEEE 802.11) y soporta una amplia configuración, entre ellas balanceo de cargas. Está publicado bajo la licencia GPL, de software libre.

Prerequisitos

En este tutorial se explicará cómo implementar un servidor OpenVPN de múltiples túneles. Las configuraciones expuestas en la guía permitirán escalabilizar la solución de su servidor a cuantos túneles virtuales sobre openvpn usted quiera desplegar, siempre y cuando los recursos hardware de su servidor lo permita. Son necesarias algunas modificaciones, como la creación de algunos directorios que serán necesarios para esta estructura escalable, así como la habilitación del reenvío de paquetes.

Habilitamos el reenvío de paquetes de manera permanente:

nano /etc/sysctl.conf

Descomentamos la siguiente línea:

net.ipv4.ip_forward=1

Preparamos los directorios necesarios:

-Directorio para salvas temporales de los certificados generados por ovpnN (donde N hace referencia al # que identifica al servidor openvpn)

mkdir -p /mnt/backup/ovpn1

-Directorio para configurar la reservación de IP por el tunel ovpnN:

mkdir -p /etc/openvpn/ovpn1/ccd

-Directorio para albergar las herramientas para la PKI:

mkdir -p /config/ovpn1-easy-rsa

-Directorio que albergará la ca, dh y llave del servidor:

mkdir -p /config/auth/ovpn1

-Directorio para scripts del sistema. Aquí habrá un script que explicaremos más adelante, para que la gestión de los múltiples servidores ovpnN sea más cómoda:

mkdir -p /config/scripts

1-Instalación de OpenVPN por repositorios

apt-get install openvpn easy-rsa

2-Configuración de OpenVPN

Copiando fichero de configuración del servidor de los ejemplos de openvpn:

gunzip -c /usr/share/doc/openvpn/examples/sample-config-files/server.conf.gz > /etc/openvpn/ovpn1-server.conf

Editando el fichero de configuración del servidor:

nano /etc/openvpn/ovpn1-server.conf

Adaptando a su entorno:

#################################################
# Sample OpenVPN 2.0 config file for #
# multi-client server. #
# #
# This file is for the server side #
# of a many-clients <-> one-server #
# OpenVPN configuration. #
# #
# OpenVPN also supports #
# single-machine <-> single-machine #
# configurations (See the Examples page #
# on the web site for more info). #
# #
# This config should work on Windows #
# or Linux/BSD systems. Remember on #
# Windows to quote pathnames and use #
# double backslashes, e.g.: #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
# #
# Comments are preceded with '#' or ';' #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d
local 172.16.12.2

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one. You will need to
# open up this port on your firewall.
port 11941

# TCP or UDP server?
;proto tcp
proto udp

# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one. On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key). Each client
# and the server must have their own cert and
# key file. The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys. Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
;ca ca.crt
;cert server.crt
;key server.key # This file should be kept secret
ca /config/auth/ovpn1/ca.crt
cert /config/auth/ovpn1/server.crt
key /config/auth/ovpn1/server.key

# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh2048.pem 2048
;dh dh2048.pem
dh /config/auth/ovpn1/dh2048.pem

# Network topology
# Should be subnet (addressing via IP)
# unless Windows clients v2.0.9 and lower have to
# be supported (then net30, i.e. a /30 per client)
# Defaults to net30 (not recommended)
;topology subnet

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
;server 10.8.0.0 255.255.255.0
server 192.168.10.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file. If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface. Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0. Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients. Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses. You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge

# Push routes to the client to allow it
# to reach other private subnets behind
# the server. Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
# iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN. This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
# ifconfig-push 10.9.0.1 10.9.0.2
client-config-dir /etc/openvpn/ovpn1/ccd

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients. There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
# group, and firewall the TUN/TAP interface
# for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
# modify the firewall in response to access
# from different clients. See man
# page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
;push "redirect-gateway def1 bypass-dhcp"

# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
;push "dhcp-option DNS 208.67.222.222"
;push "dhcp-option DNS 208.67.220.220"
push "dhcp-option DNS 192.168.9.2"

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client
client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names. This is recommended
# only for testing purposes. For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120

# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
# openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
# Note that 2.4 client/server will automatically
# negotiate AES-256-GCM in TLS mode.
# See also the ncp-cipher option in the manpage
cipher AES-256-CBC

# Enable compression on the VPN link and push the
# option to the client (2.4+ only, for earlier
# versions see below)
;compress lz4-v2
;push "compress lz4-v2"

# For compression compatible with older clients use comp-lzo
# If you enable it here, you must also
# enable it in the client config file.
;comp-lzo
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody
;group nogroup
user nobody
group nogroup

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
;status openvpn-status.log
status /etc/openvpn/ovpn1/openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it. Use one
# or the other (but not both).
;log openvpn.log
;log-append openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3

# Silence repeating messages. At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20

# Notify the client that when the server restarts so it
# can automatically reconnect.
explicit-exit-notify 1

Configurando IP estática para el cliente (reservación de IP). Esto es necesario cuando configura servidores, los cuales deberían tener siempre la misma IP por dentro del tunel. Para ello editamos el siguiente fichero:

nano /etc/openvpn/ovpn1/ccd/client

Agregar lo siguiente (adaptar a su entorno de red):

#ifconfig-push [local] [remote]

ifconfig-push 192.168.10.3 192.168.10.4

3-Configuración de la PKI

Copiando el directorio «/usr/share/easy-rsa/» y pegarlo en «/config/ovpn1-easy-rsa/»:

cp -rv /usr/share/easy-rsa/* /config/ovpn1-easy-rsa/

Acceder al directorio «/config/ovpn1-easy-rsa/easy-rsa»:

cd /config/ovpn1-easy-rsa/

Editamos el fichero «vars»:

nano vars

Modificamos las siguientes líneas, según el entorno de la red:

export CA_EXPIRE=3650
export KEY_EXPIRE=3650
export KEY_COUNTRY="CU"
export KEY_PROVINCE="HA"
export KEY_CITY="LaHabana"
export KEY_ORG="NODO"
export KEY_EMAIL="[email protected]"
export KEY_OU="REDES"
export KEY_NAME="ovpn1-server"

Inicializando la PKI:

source ./vars

NOTA: Si da 8un error que no se encuentra el fichero «openssl.cnf» tomar uno de los que está de ejemplos y cambiarle el nombre
cp openssl-1.0.0.cnf openssl.cnf

Intentamos nuevamente inicializar la PKI:

source ./vars
./clean-all

NOTA: Más adelante se presentará un script para automatizar el trabajo con la PKI y la manera en que se copian los certificados. Si usted ya tiene ese script y desea agregar un nuevo tunel ovpnN, hasta este paso es necesario todo lo anterior (adaptanto al nuevo ovpnN, tanto en directorios como en fichero de configuración), ya que en lo adelante todo lo hace el script.

Construimos la ca, el dh, llaves y certificados (No pondremos contraseña a los certificados):

./build-ca
./build-dh
./build-key-server ovpn1-server

Copiar los archivos del servidor:

cp /config/ovpn1-easy-rsa/keys/ca.crt /config/auth/ovpn1/
cp /config/ovpn1-easy-rsa/keys/dh2048.pem /config/auth/ovpn1/
cp /config/ovpn1-easy-rsa/keys/ovpn1-server.key /config/auth/ovpn1/
cp /config/ovpn1-easy-rsa/keys/ovpn1-server.crt /config/auth/ovpn1/

4-Generación de certificados para los clientes

cd /config/ovpn1-easy-rsa/
source ./vars
./build-key client

Obtener los archivos para el cliente («ca.crt», «client.key», «client.crt»). Hay varias formas de enviar estos archivos, en este caso se hace uso de la herramienta de Windows WinSCP. Se loguea por SSH y se copia por SCP:

5-Inicializar ovpn1 en el servidor

Reiniciamos openvpn:

service openvpn restart

Conectándonos al tunel vtun0 (ovpn1):

cd /etc/openvpn/
openvpn ovpn1-server.conf

6-Instalación y configuración del cliente OpenVPN en un host Linux

Instalando OpenVPN:

apt-get install openvpn

Copiando fichero de configuracion de cliente ovpn de los ejemplos

cp /usr/share/doc/openvpn/examples/sample-config-files/client.conf /etc/openvpn/ovpn1-client.conf

Editamos el fichero de configuración del cliente ovpn1:

nano /etc/openvpn/ovpn1-client.conf

Dentro modificamos según convenga. A continuación configuramos el cliente para que se conecte al servidor ovpn1:

##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server. #
# #
# This configuration can be used by multiple #
# clients, however each client should have #
# its own cert and key files. #
# #
# On Windows, you might want to rename this #
# file so it has a .ovpn extension #
##############################################

# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client

# Use the same setting as you are using on
# the server.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel
# if you have more than one. On XP SP2,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap

# Are we connecting to a TCP or
# UDP server? Use the same setting as
# on the server.
;proto tcp
proto udp

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
;remote my-server-1 1194
;remote my-server-2 1194
remote 172.16.4.2 11941

# Choose a random host from the remote
# list for load-balancing. Otherwise
# try hosts in the order specified.
;remote-random

# Keep trying indefinitely to resolve the
# host name of the OpenVPN server. Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite

# Most clients don't need to bind to
# a specific local port number.
nobind

# Downgrade privileges after initialization (non-Windows only)
;user nobody
;group nogroup
user nobody
group nogroup

# Try to preserve some state across restarts.
persist-key
persist-tun

# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here. See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]

# Wireless networks often produce a lot
# of duplicate packets. Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings

# SSL/TLS parms.
# See the server config file for more
# description. It's best to use
# a separate .crt/.key file pair
# for each client. A single ca
# file can be used for all clients.
ca /etc/openvpn/ovpn1/ca.crt
cert /etc/openvpn/ovpn1/client.crt
key /etc/openvpn/ovpn1/client.key

# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server". This is an
# important precaution to protect against
# a potential attack discussed here:
# http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server". The build-key-server
# script in the easy-rsa folder will do this.
ns-cert-type server

# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1

# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x

# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo

# Set log file verbosity.
verb 3

# Silence repeating messages
;mute 20

7-Inicializar ovpn1 en el cliente

Copiar los certificados generados para el cliente y pegarlos en el directorio especificado por el cliente. En este caso «/etc/openvpn/ovpn1». Una forma de hacerlo, ademas de WinSCp, es por scp:

scp root@ovpn_server_ip:/config/ovpn1-easy-rsa/keys/ca.crt /etc/openvpn/ovpn1
scp root@ovpn_server_ip:/config/ovpn1-easy-rsa/keys/client.crt /etc/openvpn/ovpn1
scp root@ovpn_server_ip:/config/ovpn1-easy-rsa/keys/client.key /etc/openvpn/ovpn1

Reiniciamos el cliente ovpn:

service openvpn restart

Conectarse al tunel ovpn1:

cd /etc/openvpn
openvpn ovpn1-client.conf

Esto hará que se ejecute el cliente, pero si queremos que inicie automáticamente, basta con reiniciar el servidor y el programa se iniciará, sin imposibilitarnos trabajar en la consola. Usted puede repetir el procedimiento hecho para ovpn1, para tantos ovpnN sus recursos hardware lo permitan en el servidor. Respetando la estructura descrita para los directorios, usted puede lograr múltiples servidores ovpn, en un mismo servidor OpenVPN. La siguiente imagen muestar un ejemplo de un servidor OpenVPN con 4 túneles, como si de un router VyOS o RouterOS se tratase:

8-Automazación de OpenVPN

Creando script para automatizar openvpn:

mkdir -p /config/scripts
nano /config/scripts/cert.sh

Agregar lo siguiente:

#!/bin/bash

#----------------------------------------------------------------------------------------------------------------------
# Este script tiene como objetivo automatizar la creacion de certificados y llaves para los ovpnx que se tienen en el
#servidor. El script logra automatizar este proceso y empaquetando el certificado y guardandolo via scp en el host que
#contiene los directorios de salvas "ftp1.nodo.local". Si se crea una nueva ca, dh y server.key, sera necesario reiniciar
#el servicio de openvpn.
#----------------------------------------------------------------------------------------------------------------------

###################
# VARIABLES FIJAS #
###################

scripts="/config/scripts"
FECHA="$(date +%d-%b-%Y)"
#
USUARIO="ftpadmin" # usuario del ftp
PASSWORD="ftpadmin" # password del usuario del ftp
HOSTREMOTO="ftp1.nodo.local" # ip o hostname del ftp
DIR="salvaguarda/fw1/$1" # directorio del ftp

if [ $1 = "-h" ];
          then
                 clear
                 echo ""
                 echo "================================"
                 echo "Script para Automatizar de ovpnN"
                 echo "================================"
                 echo ""
                 echo "Ayuda:"
                 echo "sitaxis: <. ./camino_al_script> <var1> <var2> <var3>"
                 echo ""
                 echo "<var1>:"
                 echo "-h Muestra esta ayuda"
                 echo "ovpnN Especifica el servidor ovpn, donde N puede ser: 0, 1, 2, ..."
                 echo ""
                 echo "<var2>:"
                 echo "-s Crea la CA, DH, llave y certificado del servidor"
                 echo "-u Crea llave y certificado del cliente"
                 echo ""
                 echo "<var3>:"
                 echo "<texto> uid para nombrar certificado del cliente"
                 echo ""
          exit 0
fi

if [ $1 == "ovpn1" ];
          then
                 easyrsa="/config/ovpn1-easy-rsa"
                 ovpn="/config/auth/ovpn1"
                 backup="/mnt/backup/ovpn1"
fi

if [ $1 == "ovpn2" ];
          then
                 easyrsa="/config/ovpn2-easy-rsa"
                 ovpn="/config/auth/ovpn2"
                 backup="/mnt/backup/ovpn2"
fi

if [ $1 == "ovpn3" ];
          then
                 easyrsa="/config/ovpn3-easy-rsa"
                 ovpn="/config/auth/ovpn3"
                 backup="/mnt/backup/ovpn3"
fi

if [ $1 == "ovpn4" ];
          then
                 easyrsa="/config/ovpn4-easy-rsa"
                 ovpn="/config/auth/ovpn4"
                 backup="/mnt/backup/ovpn4"
fi

if [ $2 == "-s" ];
          then
                 clear
                 echo ""
                 echo "=============================="
                 echo "Deteniendo el Servicio openvpn"
                 echo "=============================="
                 service openvpn stop
                 echo ""
                 echo "===================================================="
                 echo "Borrando Ficheros de Configuracion Antiguos de ovpn0"
                 echo "===================================================="
                 rm -f $ovpn/*
                 rm -f $backup/*
                 cd $easyrsa
                 source ./vars
                 ./clean-all
                 echo ""
                 echo "==============="
                 echo "Generando la CA"
                 echo "==============="
                 ./build-ca
                 echo ""
                 echo "==============="
                 echo "Generando el DH"
                 echo "==============="
                 ./build-dh
                 echo ""
                 echo "=========================================="
                 echo "Generando Llave y Certificado del Servidor"
                 echo "=========================================="
                 ./build-key-server server
                 echo ""
                 echo "============================"
                 echo "Guardando Ficheros Generados"
                 echo "============================"
                 cp keys/ca* $ovpn
                 cp keys/dh* $ovpn
                 cp keys/server* $ovpn
                 echo ""
                 echo "=============================="
                 echo "Iniciando el Servicion openvpn"
                 echo "=============================="
                 service openvpn start
                 echo ""
                 echo "=============="
                 echo "Fin del Script"
                 echo "=============="
                 echo ""
                 cd $scripts
fi

if [ $2 == "-u" ];
         then
                 clear
                 echo ""
                 echo "================================"
                 echo "Eliminando Antiguos Certificados"
                 echo "================================"
                 rm -rf $backup
                 rm -rf $ovpn/$3*
                 cd $easyrsa
                 source ./vars
                 echo ""
                 echo "========================================="
                 echo "Generando Llave y Certificado del Cliente"
                 echo "========================================="
                 ./build-key $3
                 echo ""
                 echo "============================"
                 echo "Guardando Ficheros Generados"
                 echo "============================"
                 mkdir -p $ovpn
                 cp keys/$3* $ovpn
                 mkdir -p $backup
                 cp keys/ca.crt $backup
                 cp keys/$3* $backup
                 chmod 777 $backup/*
                 cd $backup
                 echo ""
                 echo "=============================="
                 echo "Creando Fichero Unico de Salva"
                 echo "=============================="
                 tar -zcf $3-$1-$FECHA.tgz $backup
          else
                 exit 1
fi

echo "====================================="
echo "Guardando en el FTP de $HOSTREMOTO"
echo "====================================="
ftp -inv << BUKAERA
open $HOSTREMOTO
user $USUARIO $PASSWORD
pwd
hash
cd $DIR
put $3-$1-$FECHA.tgz
bye
BUKAERA

NOTA: El script requiere de un servidor ftp que responde en este caso al nombre «ftp1.nodo.local». Usted puede crearlo en el propio localhost o o con otro nombre

Dando permisos de ejecución al script:

chmod +x /config/scripts/cert.sh

Probando la ayuda del script

/config/scripts/cert.script -h

Debe devolvernos lo siguiente:

================================
Script para Automatizar de ovpnN
================================

Ayuda:
sitaxis: <. ./camino_al_script> <var1> <var2> <var3>

<var1>:
-h Muestra esta ayuda
ovpnN Especifica el servidor ovpn, donde N puede ser: 0, 1, 2, ...

<var2>:
-s Crea la CA, DH, llave y certificado del servidor
-u Crea llave y certificado del cliente

<var3>:
<texto> uid para nombrar certificado del cliente

Creando un servidor ovpn2

/config/scripts/cert.script ovpn2 -s

Debe devolvernos lo siguiente:

==============================
Deteniendo el Servicio openvpn
==============================

====================================================
Borrando Ficheros de Configuracion Antiguos de ovpn0
====================================================
NOTE: If you run ./clean-all, I will be doing a rm -rf on /config/ovpn2-easy-rsa/keys

===============
Generando la CA
===============
Generating a 2048 bit RSA private key
.................................................+++
.............................................................+++
writing new private key to 'ca.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [CU]:
State or Province Name (full name) [HA]:
Locality Name (eg, city) [LaHabana]:
Organization Name (eg, company) [NODO]:
Organizational Unit Name (eg, section) [REDES]:
Common Name (eg, your name or your server's hostname) [NODO CA]:
Name [ovpn2-server]:
Email Address [[email protected]]:

===============
Generando el DH
===============
Generating DH parameters, 2048 bit long safe prime, generator 2
This is going to take a long time
........................+..............................................+...+...........+...+..............................................................................................................................+.......................................................................................................................................................................................++*++*

==========================================
Generando Llave y Certificado del Servidor
==========================================
Generating a 2048 bit RSA private key
..+++
.....+++
writing new private key to 'server.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [CU]:
State or Province Name (full name) [HA]:
Locality Name (eg, city) [LaHabana]:
Organization Name (eg, company) [NODO]:
Organizational Unit Name (eg, section) [REDES]:
Common Name (eg, your name or your server's hostname) [server]:
Name [ovpn2-server]:
Email Address [[email protected]]:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /config/ovpn2-easy-rsa/openssl.cnf
Can't open /config/ovpn2-easy-rsa/keys/index.txt.attr for reading, No such file or directory
140184640554240:error:02001002:system library:fopen:No such file or directory:../crypto/bio/bss_file.c:74:fopen('/config/ovpn2-easy-rsa/keys/index.txt.attr','r')
140184640554240:error:2006D080:BIO routines:BIO_new_file:no such file:../crypto/bio/bss_file.c:81:
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName :PRINTABLE:'CU'
stateOrProvinceName :PRINTABLE:'HA'
localityName :PRINTABLE:'LaHabana'
organizationName :PRINTABLE:'NODO'
organizationalUnitName:PRINTABLE:'REDES'
commonName :PRINTABLE:'server'
name :PRINTABLE:'ovpn2-server'
emailAddress :IA5STRING:'[email protected]'
Certificate is to be certified until Aug 19 19:35:27 2029 GMT (3650 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

============================
Guardando Ficheros Generados
============================

==============================
Iniciando el Servicion openvpn
==============================

==============
Fin del Script
==============

Iniciando el servidor

openvpn ovpn2-server.conf

Debe devolver algo como esto:

Thu Aug 22 16:16:19 2019 OpenVPN 2.4.0 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on Jul 18 2017
Thu Aug 22 16:16:19 2019 library versions: OpenSSL 1.0.2l 25 May 2017, LZO 2.08
Thu Aug 22 16:16:19 2019 Diffie-Hellman initialized with 2048 bit key
Thu Aug 22 16:16:19 2019 ROUTE_GATEWAY 172.16.12.1/255.255.255.252 IFACE=eth0 HWADDR=ca:51:5e:94:05:88
Thu Aug 22 16:16:19 2019 TUN/TAP device tun0 opened
Thu Aug 22 16:16:19 2019 TUN/TAP TX queue length set to 100
Thu Aug 22 16:16:19 2019 do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Thu Aug 22 16:16:19 2019 /sbin/ip link set dev tun0 up mtu 1500
Thu Aug 22 16:16:19 2019 /sbin/ip addr add dev tun0 local 192.168.20.1 peer 192.168.20.2
Thu Aug 22 16:16:19 2019 /sbin/ip route add 192.168.20.0/24 via 192.168.20.2
Thu Aug 22 16:16:19 2019 Could not determine IPv4/IPv6 protocol. Using AF_INET
Thu Aug 22 16:16:19 2019 Socket Buffers: R=[212992->212992] S=[212992->212992]
Thu Aug 22 16:16:19 2019 UDPv4 link local (bound): [AF_INET]172.16.12.2:11941
Thu Aug 22 16:16:19 2019 UDPv4 link remote: [AF_UNSPEC]
Thu Aug 22 16:16:19 2019 GID set to nogroup
Thu Aug 22 16:16:19 2019 UID set to nobody
Thu Aug 22 16:16:19 2019 MULTI: multi_init called, r=256 v=256
Thu Aug 22 16:16:19 2019 IFCONFIG POOL: base=192.168.20.4 size=62, ipv6=0
Thu Aug 22 16:16:19 2019 ifconfig_pool_read(), in='pdc,192.168.20.4', TODO: IPv6
Thu Aug 22 16:16:19 2019 succeeded -> ifconfig_pool_set()
Thu Aug 22 16:16:19 2019 IFCONFIG POOL LIST
Thu Aug 22 16:16:19 2019 pdc,192.168.20.4
Thu Aug 22 16:16:19 2019 Initialization Sequence Completed

Al reinicar el servidor todos los servidores ovpnN que se encuentren configurados iniciarán automáticamente.

A continuación, imágenes que muestran cómo se exportó satisfactoriamente los certificados al ftp que los albergará:

Usted puede configurar el cliente con proxy apoyándose en la documentación realizada por Luis Felipe Domínguez Vega aquí.