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| − | =Introduction=
| + | [[File:Introduction-icon.png|link=VPN|64px|caption|VPN introduction]] |
| | + | [[VPN|VPN introduction]] |
| | | | |
| − | See [[VPN|VPN introduction]]
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| | + | [[File:Vpn-server-config-icon.png|link=VPN server configuration|64px|caption|VPN server configuration]] |
| | + | [[VPN server configuration|OpenVPN server configuration (server.conf)]] |
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| | + | [[File:Ssl certificate icon.jpg|link=VPN certificates management|64px|caption|VPN certificates management]] |
| | + | [[VPN certificates management]] |
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| − | =Server installation=
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| − | | + | [[File:Internet security.png|link=VPN security|64px|caption|VPN security]] |
| − | ==Binary==
| + | [[VPN security]] |
| − | | |
| − | Installation is easy. You just need “openvpn”.
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | apt-get update && apt-get upgrade
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| − | apt-get install openvpn easy-rsa
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| − | </syntaxhighlight>
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| − | | |
| − | ==Logs==
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| − | | |
| − | Create target files
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| − | <syntaxhighlight lang="bash">
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| − | touch /var/log/openvpn.log
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| − | touch /var/log/openvpn-status.log
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| − | chmod 777 /var/log/openvpn*
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| − | </syntaxhighlight>
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| − | Create symlinks
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | ln -s /var/log/openvpn.log /etc/openvpn/openvpn.log
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| − | ln -s /var/log/openvpn-status.log /etc/openvpn/openvpn-status.log
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| − | </syntaxhighlight>
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| − | Adjust '/etc/openvpn/server.conf' accordingly
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | /var/log/openvpn.log => real time log
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| − | /var/log/openvpn-status.log => list of connected clients
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| − | </syntaxhighlight>
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| − | =Public Key Infrastructure=
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| − | | |
| − | The OpenVPN package provides a set of encryption-related tools called "easy-rsa".
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| − | | |
| − | These scripts are located by default in the ''/usr/share/doc/openvpn/examples/easy-rsa/'' directory.
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| − | | |
| − | However, in order to function properly, these scripts should be located in the /etc/openvpn directory.
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| − | ==Installation==
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| − | Copy these files with the following command:
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| − | | |
| − | [Old Ubuntu - before 14.04]
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| − | <syntaxhighlight lang="bash">
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| − | cp -R /usr/share/doc/openvpn/examples/easy-rsa/ /etc/openvpn
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| − | </syntaxhighlight>
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| − | | |
| − | [New Ubuntu distro - 14.04 and later]
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| − | <syntaxhighlight lang="bash">
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| − | cp -R /usr/share/easy-rsa/ /etc/openvpn
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| − | </syntaxhighlight>
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| − | | |
| − | ==Configure Public Key Infrastructure Variables==
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| − | ===Default values===
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| − | Before you can generate the public key infrastructure for OpenVPN, you must configure a few variables that the easy-rsa scripts will use to generate the scripts.
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| − | These variables are set near the end of the /etc/openvpn/easy-rsa/2.0/vars file.
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| − | [Old Ubuntu]
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| − | Don't forget to add /etc/openvpn/easy-rsa/'''2.0/''' everywhere !!
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | vim /etc/openvpn/easy-rsa/vars
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | Here is an example of the relevant values:
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | export KEY_COUNTRY="SE"
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| − | export KEY_PROVINCE="Västra Götaland"
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| − | export KEY_CITY="Goteborg"
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| − | export KEY_ORG="daxiongmao.eu"
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| − | export KEY_EMAIL="guillaume@qin-diaz.com"
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| − | </syntaxhighlight>
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| − | | |
| − | >> Alter the examples to reflect your configuration.
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| − | | |
| − | This information will be included in certificates you create!
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| − | That must be accurate, particularly the KEY_ORG and KEY_EMAIL values.
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| − | | |
| − | ===Initialize the Public Key Infrastructure (PKI)===
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| − | Generate the Authority of Certification (AC):
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/easy-rsa/
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| − | . /etc/openvpn/easy-rsa/vars
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| − | . /etc/openvpn/easy-rsa/clean-all
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| − | . /etc/openvpn/easy-rsa/build-ca
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| − | </syntaxhighlight>
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| − | | |
| − | When asked, use your COMPANY name as "common name".
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| − | | |
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| − | | |
| − | ===Generate OpenVPN Server Certificates and Private Key===
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/easy-rsa/
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| − | source /etc/openvpn/easy-rsa/vars
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| − | . /etc/openvpn/easy-rsa/build-key-server [server]
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| − | </syntaxhighlight>
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| − | [server] replace server by your actual server name !
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| − | | |
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| − | This script will also prompt you for additional information.
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| − | Common Name = Name of the current server (server DNS name)
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| − | ===Generate Clients certificates and private keys===
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/easy-rsa/
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| − | source /etc/openvpn/easy-rsa/vars
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| − | . /etc/openvpn/easy-rsa/build-key [clientName]
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| − | </syntaxhighlight>
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| − | Replace the ''[clientName]'' parameter with a relevant identifier for each client.
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| − | * The client common name must be unique
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| − | * It helps you to identify each client. Don’t hesitate to use meaningful name.
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| − | The name is put inside the certificate.
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| − | All other information can remain the same
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| − | ===Generate Diffie Hellman Parameters===
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| − | The "Diffie Hellman Parameters" govern the method of key exchange and authentication used by the OpenVPN server.
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/easy-rsa/
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| − | . /etc/openvpn/easy-rsa/build-dh
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ===Generate shared security key===
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| − | '''NOT TESTED – July 2013'''
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| − | To increase security, you can use a share common key between server and clients.
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| − | Each client will need the shared key + its own key to communicate.
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| − | <syntaxhighlight lang="bash">
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| − | openvpn --genkey --secret ./keys/ta.key
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| − | </syntaxhighlight>
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| − | ==Distribute keys==
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| − | ===Client files===
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| − | In order to authenticate to the VPN, you'll need to copy a number of certificate and key files to the remote client machines.
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| − | They are:
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| − | * Authority of certification ca.crt
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| − | * Client certificate [clientName].crt
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| − | * Client private key [clientName].key
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| − | | |
| − | !!! These keys should transferred with the utmost attention to security.
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| − | Anyone who has the key is able to gain full access to your virtual private network !!!
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| − |
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| − | ===Server files===
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| − | The keys and certificates for the server need to be relocated to the /etc/openvpn directory so the OpenVPN server process can access them.
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| − | These files are:
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| − | * Authority of certification ca.crt
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| − | * Authority private key ca.key
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| − | * Diffie Hellman props dh2048.pem !! on new distro it might be higher by default !!
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| − | * Server certificate server.crt
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| − | * Server private key server.key
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/
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| − | ln -s /etc/openvpn/easy-rsa/keys/ca.crt /etc/openvpn/ca.crt
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| − | ln -s /etc/openvpn/easy-rsa/keys/ca.key /etc/openvpn/ca.key
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| − | ln -s /etc/openvpn/easy-rsa/keys/dh2048.pem /etc/openvpn/dh2048.pem
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| − | ln -s /etc/openvpn/easy-rsa/keys/myServer.crt /etc/openvpn/server.crt
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| − | ln -s /etc/openvpn/easy-rsa/keys/myServer.key /etc/openvpn/server.key
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| − | </syntaxhighlight>
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| − | !! Apart 'ca.crt', all these files mustn't leave your server!!
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| − | ==Revoking Client Certificates==
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| − | ''How to remove a user's access to the VPN server?''
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| − | <syntaxhighlight lang="bash">
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| − | cd /etc/openvpn/easy-rsa/
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| − | . /etc/openvpn/easy-rsa/vars
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| − | . /etc/openvpn/easy-rsa/evoke-full [clientName]
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| − | </syntaxhighlight>
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| − | This will revoke the ability of users who have the [clientName] certificate to access the VPN.
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| − | For this reason, keeping track of which users are in possession of which certificates is crucial.
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| − | =Server configuration=
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| − | ==Configuration file==
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| − | ===Basic setup===
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| − | <syntaxhighlight lang="bash">
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| − | cp /usr/share/doc/openvpn/examples/sample-config-files/server.conf.gz /etc/openvpn
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| − | cd /etc/openvpn/
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| − | gzip -d server.conf.gz
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| − | </syntaxhighlight>
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| − | ===Security algorithms and hash===
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| − | '''Cryptographic algorithms'''
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| − | <syntaxhighlight lang="bash">
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| − | openvpn --show-ciphers
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| − | </syntaxhighlight>
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| − | Search for: AES-128-CBC, AES-256-CBC
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| − | '''Hash algorithms'''
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| − | <syntaxhighlight lang="bash">
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| − | openvpn --show-digests
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| − | </syntaxhighlight>
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| − | Search for: MD5
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| − | '''Handshake algorithms'''
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| − | <syntaxhighlight lang="bash">
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| − | openvpn --show-tls
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| − | </syntaxhighlight>
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| − | ==Configuration example==
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| − | This is how you configuration should look like:
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| − | <syntaxhighlight lang="bash">
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| − | #################################################
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| − | # OpenVPN 2.0 config file #
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| − | # --------------------------------------------- #
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| − | # version 1.0 - April 2011 - Guillaume Diaz
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| − | # version 1.2 - June 2013 - Guillaume Diaz
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| − | # conf update + chroot
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| − | #################################################
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| − | | |
| − | # OpenVPN configuration
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| − | ##########################
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| − | # Which local IP address should OpenVPN listen on? (optional)
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| − | local 192.168.1.2
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| − | | |
| − | # VPN interface
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| − | # Which TCP/UDP port should OpenVPN listen on?
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| − | # TCP or UDP server?
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| − | dev tun
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| − | proto udp
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| − | port 8080
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| − | # SECURITY - Crypto
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| − | ########################
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| − | # SSL/TLS root certificate (ca)
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| − | # Server certificate and private key
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| − | # Diffie hellman parameters
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| − | ca /etc/openvpn/ca.crt
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| − | cert /etc/openvpn/server.crt
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| − | key /etc/openvpn/server.key
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| − | dh /etc/openvpn/dh2048.pem
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| − | # Shared secret key by both server and clients
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| − | ;tls-auth /etc/openvpn/ta.key 0
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| − | | |
| − | # Crypto settings
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| − | cipher AES-128-CBC
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| − | auth MD5
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| − | # Reduce OpenVPN daemon rights after application start
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| − | # To chroot OpenVPN to its own folder
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| − | user nobody
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| − | group nogroup
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| − | chroot /etc/openvpn/
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| − | # SERVER CONF
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| − | ##########################
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| − | # Server mode and VPN subset
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| − | server 192.168.15.0 255.255.255.0
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| − | # Maintain a record of client <-> virtual IP address associations in this file.
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| − | ifconfig-pool-persist ipp.txt
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| − | # Keepalive (ping-like)
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| − | # 1 ping every 10s. 120s timeout = disconnect client
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| − | keepalive 10 120
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| − | # Keep server connection up and running
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| − | persist-key
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| − | persist-tun
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| − | # Compression of data exchange
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| − | comp-lzo
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| − | # CLIENTS CONF
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| − | ##########################
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| − | # Maximum number of concurrently connected clients
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| − | ;max-clients 100
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| − | | |
| − | # Allow different clients to be able to "see" each other.
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| − | client-to-client
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| − | # One certificate, multiple clients
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| − | # Do not use 'duplicate-cn' with 'ifconfig-pool-persist'
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| − | ;duplicate-cn
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| − | # Fix for Microsoft Windows clients
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| − | mssfix
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| − | # Server security level
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| − | script-security 2
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| − | # Push routes to the client
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| − | # >> VPN route. required to allow connections
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| − | push "route 192.168.15.0 255.255.255.0"
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| − | # >> Set the VPN server as global gateway
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| − | push "redirect-gateway def1"
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| − | # >> set the DNS Server
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| − | push "dhcp-option DNS 8.8.8.8"
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| − | push "dhcp-option DNS 8.8.4.4"
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| − | # LOGS
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| − | ##########################
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| − | # Short status file showing current connections
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| − | # this is truncated and rewritten every minute.
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| − | status /etc/openvpn/openvpn-status.log
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| − | | |
| − | # Log in a dedicated file instead of /var/log/messages
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| − | log /etc/openvpn/openvpn.log
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| − | log-append /etc/openvpn/openvpn.log
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| − | | |
| − | # Log level
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| − | # 0 is silent, except for fatal errors
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| − | # 4 is reasonable for general usage
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| − | # 5 and 6 can help to debug connection problems
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| − | # 9 is extremely verbose
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| − | verb 6
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| − | | |
| − | # Silence repeating messages.
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| − | # At most xx sequential same messages will be output to the log file.
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| − | mute 10
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| − | </syntaxhighlight>
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| − | You can either use TCP or UDP. Performances are the same, UDP is a bit easier to install.
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| − | | |
| − | Be careful when you choose the port number!
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| − | Common open ports:
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| − | * 80 (http)
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| − | * 443 (HTTPS)
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| − | * 8080 (Proxy / JEE servers)
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| − | =Server security: Fail2ban=
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| − | It's a good idea to protect your server against brute force attacks and intruders.
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| − | | |
| − | See [[Fail2ban#VPN rule]]
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| − | =Server: Advanced stuff=
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| − | Logrotate
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| − | http://guillaume.vaillant.me/?p=393
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| − | | |
| − | -- TO BE FINISHED --
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| − | =Firewall=
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| − | | |
| − | See [[Firewall VPN]]
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