ein Beispiel um einen OpenVPN Server einzurichten und Client anzulegen
apt install openvpn easy-rsa
in Datei diesen Wert setzen
/etc/sysctl.conf
net/ipv4/ip_forward=1
interface Name "ens6 " anpassen und IP setzen “IP-vom-OpenVPN-Server”
das muss bei jedem reboot geladen werden, sollte rc.local nicht installiert sein gibt es auch andere wege um das beim reboot zu laden
/etc/rc.local
#!/bin/bash
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -A POSTROUTING -o ens6 -j SNAT --to IP-vom-OpenVPN-Server
iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o ens6 -s 10.8.0.0/24 -j MASQUERADE
exit 0
Systemdienst erstellen
ln -s /lib/systemd/system/openvpn@.service /etc/systemd/system/openvpn@vpn-srv.service
systemctl daemon-reload
systemctl enable openvpn@vpn-srv.service
easy-rsa Default Dateien kopieren und in das Verzeichnis wechseln
cp -rp /usr/share/easy-rsa/ /etc/openvpn/easy-rsa3
cp -r /etc/openvpn/easy-rsa3/vars.example /etc/openvpn/easy-rsa3/vars
cd /etc/openvpn/easy-rsa3
Datei erstellen
/etc/openvpn/easy-rsa3/make_config.sh
#!/bin/bash
# .ovpn Konfiguration erstellen, ausführen, script + client-name (./make_config.sh openvpn-client1)
BASE_CONFIG=/etc/openvpn/easy-rsa3/base.conf
CA_DIR=/etc/openvpn/easy-rsa3/pki
CERT_DIR=/etc/openvpn/easy-rsa3/pki/issued
KEY_DIR=/etc/openvpn/easy-rsa3/pki/private
OUTPUT_DIR=/etc/openvpn/easy-rsa3/client
cat ${BASE_CONFIG} \
<(echo -e '<ca>') \
${CA_DIR}/ca.crt \
<(echo -e '</ca>\n<cert>') \
${CERT_DIR}/${1}.crt \
<(echo -e '</cert>\n<key>') \
${KEY_DIR}/${1}.key \
<(echo -e '</key>\n<tls-auth>') \
${KEY_DIR}/ta.key \
<(echo -e '</tls-auth>') \
> ${OUTPUT_DIR}/${1}.ovpn
Beispiel Server Konfiguration erstellen, könnte ohne weitere Anpassung genutzt werden
/etc/openvpn/vpn-srv.conf
#################################################
# 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 ip-oder-domain-vom-vpn-server
mode server
# 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 1194
# TCP or UDP server?
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 /etc/openvpn/easy-rsa3/pki/ca.crt
cert /etc/openvpn/easy-rsa3/pki/issued/openvpn-server.crt
key /etc/openvpn/easy-rsa3/pki/private/openvpn-server.key # This file should be kept secret
# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh1024.pem 1024
# Substitute 2048 for 1024 if you are using
# 2048 bit keys.
dh /etc/openvpn/easy-rsa3/pki/dh.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
# 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:
;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.
client-config-dir ccd
# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;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
# 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 1.1.1.1" # Cloudflare
push "dhcp-option DNS 1.0.0.1" # Cloudflare
# 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
# 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 /etc/openvpn/easy-rsa3/pki/private/ta.key 0 # This file is secret
key-direction 0
tls-server
tls-version-min 1.2
remote-cert-tls client
tls-cipher TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384
# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
cipher AES-256-GCM
ecdh-curve secp521r1
# Die HMAC-Authentication
auth SHA512
crl-verify /etc/openvpn/easy-rsa3/pki/crl.pem
# Enable compression on the VPN link and push the
# option to the client (v2.4+ only, for earlier
# versions see below)
;compress lz4-v2
;push "compress lz4-v2"
# The maximum number of concurrently connected
# clients we want to allow.
max-clients 10
# 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
# 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 /var/log/openvpn/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 /var/log/openvpn/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 4
# 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
#sndbuf 393216
#rcvbuf 393216
#push "sndbuf 393216"
#push "rcvbuf 393216"
auth-nocache
Default Client Konfiguration erstellen
IP vom VPN-Server muss angepasst werden in der Zeile
“remote ip-oder-domain-vom-vpn-server 1194”
/etc/openvpn/easy-rsa3/base.conf
##############################################
# client-side OpenVPN 2.x config file #
# 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 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 udp
# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote ip-oder-domain-vom-vpn-server 1194
;remote my-server-2 1194
# 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
# 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
# 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
remote-cert-tls server
# If a tls-auth key is used on the server
# then every client must also have the key.
tls-auth ta.key 1
key-direction 1
tls-version-min 1.2
tls-client
tls-cipher TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384
# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
cipher AES-256-GCM
# Die HMAC-Authentication
auth SHA512
auth-nocache
# 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 2
# Silence repeating messages
;mute 20
Zeilen hinzufügen wen nicht vorhanden und anpassen an eigene Umgebung
/etc/openvpn/easy-rsa3/vars
set_var EASYRSA_PKI "$PWD/pki"
set_var EASYRSA_DN "org"
set_var EASYRSA_REQ_COUNTRY "DE"
set_var EASYRSA_REQ_PROVINCE "Bundesland"
set_var EASYRSA_REQ_CITY "Stadt"
set_var EASYRSA_REQ_ORG "Organisation"
set_var EASYRSA_REQ_EMAIL "email@adresse.de"
set_var EASYRSA_REQ_OU "Abteilung"
set_var EASYRSA_ALGO ec
set_var EASYRSA_CURVE secp521r1
set_var EASYRSA_KEY_SIZE 4096
set_var EASYRSA_CA_EXPIRE 3650
set_var EASYRSA_CERT_EXPIRE 3650
#set_var EASYRSA_CERT_RENEW 30
#set_var EASYRSA_CRL_DAYS 90
set_var EASYRSA_DIGEST "sha512"
neu initialisieren “alles wird gelöscht” kann auch zum zurücksetzen der Einstellungen und Zertifikate genutzt werden
/etc/openvpn/easy-rsa3/easyrsa init-pki
neue CA erstellen
/etc/openvpn/easy-rsa3/easyrsa build-ca
Diffie-Hellman-Parameter erstellen
/etc/openvpn/easy-rsa3/easyrsa gen-dh
TA.key erstellen
openvpn --genkey secret /etc/openvpn/easy-rsa3/pki/private/ta.key
Server Zertifikat erstellen, Das nopass ist wichtig, da auf dem Server voraussichtlich nicht bei jedem Start von OpenVPN das Passwort von dem privaten Schlüssel des Zertifikat eingegeben werden soll.
/etc/openvpn/easy-rsa3/easyrsa gen-req openvpn-server nopass
/etc/openvpn/easy-rsa3/easyrsa sign-req server openvpn-server
Zusätzlich erstellen wir noch die CRL-Datei für den Server, welche für widerrufene Zertifikate benötigt wird.
/etc/openvpn/easy-rsa3/easyrsa gen-crl
Client Zertifikate erstellen, anschließend ist die fertige Client Konfiguration im Verzeichnis /etc/openvpn/easy-rsa3/client und kann auf den Client übertragen werden, gespeichert wird als client1.vpn.ovpn wen man das unter Linux nutzen möchte, einfach umbenennen in client1.vpn.conf
Das nopass kann auf den Clients weggelassen werden, wenn die Verbindung manuell aktiviert wird. Dann muss aber bei jedem Start das Passwort vom privaten Schlüssel eingegeben werden.
/etc/openvpn/easy-rsa3/easyrsa gen-req client1.vpn nopass
/etc/openvpn/easy-rsa3/easyrsa sign-req client client1.vpn
/etc/openvpn/easy-rsa3/make_config.sh client1.vpn
Zertifikat widerrufen, wen einem Client die Berechtigung entzogen wird mit dem OpenVPN Server zu verbinden, “Zertifikat ist danach Ungültig und kann nicht rückgängig gemacht werden, Zertifikat muss neu erstellt werden”
/etc/openvpn/easy-rsa3/easyrsa revoke client1.vpn
/etc/openvpn/easy-rsa3/easyrsa gen-crl
die CRL ist nur für 180 Tage Gültig ab Ausstellungsdatum, danach kann sich kein Client mehr anmelden bis die CRL neu generiert wurde, es ist zu empfehlen die CRL alle paar Monate neu zu generieren, sonst wundert man sich später warum man plötzlich nicht mehr auf den VPN Server verbinden kann.
“Optional”
2 weitere Optionen für den Client , Verzeichnis auf dem Server anlegen wen noch nicht vorhanden /etc/openvpn/ccd
Datei erstellen in /etc/openvpn/ccd z.b. client1.vpn
mit dem Internen Routing über einen Client kann man z.b. an einem Standort der keine öffentliche IP hat über diesen Client der mit dem Server verbunden ist auf das Netzwerk dahinter zugreifen, man verbindet sich also ganz normal auf den VPN Server und kann auf das Lokale Netzwerk vom Client ohne Öffentliche IP zugreifen.
# Feste IP für den Client (Client-IP Subnet)
ifconfig-push 10.8.0.5 10.8.0.6
# Internes Routing zum Heimnetz über diesen Client
iroute 192.168.1.0 255.255.255.0
auf dem Client der als Bridge genutzt wird für das Interne Routing müssen noch ein paar Anpassungen gemacht werden
/etc/sysctl.conf
net/ipv4/ip_forward=1
Interface Name "ens6 " an eigene Umgebung anpassen
/etc/rc.local
#!/bin/bash
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -s 10.8.0.0/24 -j ACCEPT
iptables -A FORWARD -j REJECT
iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o ens6 -s 10.8.0.0/24 -j MASQUERADE
exit 0
wen alles eingerichtet ist kann der Server gestartet werden,
systemctl start openvpn@vpn-srv.service
Dienst Neustarten, vorsorglich wen neue Zertifikate erstellt oder das CRL neu generiert wurde
systemctl restart openvpn@vpn-srv.service