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| | + | [[Category:Linux]] |
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| | VIRTUAL PRIVATE NETWORK (VPN) | | VIRTUAL PRIVATE NETWORK (VPN) |
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| | ==Reminder: What is a “VPN”?== | | ==Reminder: What is a “VPN”?== |
| | + | |
| | + | Nice explanations: |
| | | | |
| | * French: http://www.frameip.com/vpn/ | | * French: http://www.frameip.com/vpn/ |
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| − | ==Sources==
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| | | | |
| − | * Linode: https://library.linode.com/networking/openvpn/debian-6-squeeze#sph_id7
| + | As a quick reminder, you can use a VPN for 3 things: |
| − | * WebSite (1) : http://dev.shyd.de/2011/02/dockstar-howto-setup-openvpn-debian/ | + | * Mask your source IP @ |
| | | | |
| | + | [[File:VPN change ip address 1.png|none|VPN change ip address (1)]] |
| | | | |
| | + | [[File:VPN change ip address 2.png|none|VPN change ip address (2)]] |
| | | | |
| − | =Installation=
| |
| | | | |
| | + | * Secure communication through the VPN server |
| | | | |
| − | ==Binary==
| + | [[File:VPN client to client.png|none|VPN client to client]] |
| | | | |
| − | Installation is easy. You just need “openvpn”.
| |
| | | | |
| − | <syntaxhighlight lang="bash">
| + | * Access remote LAN |
| − | apt-get update && apt-get upgrade
| |
| − | apt-get install openvpn easy-rsa
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| − | </syntaxhighlight>
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| | | | |
| − | ==Logs==
| + | [[File:VPN to lan.png|none|VPN to LAN]] |
| | | | |
| − | Create target files
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| | | | |
| − | <syntaxhighlight lang="bash">
| + | Of course you can combine some / all of these usages. |
| − | 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">
| + | ==Sources== |
| − | /var/log/openvpn.log => real time log
| |
| − | /var/log/openvpn-status.log => list of connected clients
| |
| − | </syntaxhighlight>
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| | | | |
| − | | + | * Linode: https://library.linode.com/networking/openvpn/debian-6-squeeze#sph_id7 |
| − |
| + | * WebSite (1) : http://dev.shyd.de/2011/02/dockstar-howto-setup-openvpn-debian/ |
| − | =Public Key Infrastructure=
| |
| − | | |
| − | 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.
| |
| − | | |
| − | 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]
| |
| − | <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
| |
| − | </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/2.0/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="Västergötland"
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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/2.0/
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| − | . /etc/openvpn/easy-rsa/2.0/vars
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| − | . /etc/openvpn/easy-rsa/2.0/clean-all
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| − | . /etc/openvpn/easy-rsa/2.0/build-ca
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| − | </syntaxhighlight>
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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/2.0/
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| − | source /etc/openvpn/easy-rsa/2.0/vars
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| − | . /etc/openvpn/easy-rsa/2.0/build-key-server server
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| − | </syntaxhighlight>
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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/2.0/
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| − | source /etc/openvpn/easy-rsa/2.0/vars
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| − | . /etc/openvpn/easy-rsa/2.0/build-key [clientName]
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| − | <syntaxhighlight lang="bash">
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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/2.0/
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| − | . /etc/openvpn/easy-rsa/2.0/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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| − | | |
| − |
| |
| − | ===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 dh1024.pem
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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/2.0/keys/ca.crt /etc/openvpn/ca.crt
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| − | ln -s /etc/openvpn/easy-rsa/2.0/keys/ca.key /etc/openvpn/ca.key
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| − | ln -s /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem /etc/openvpn/dh1024.pem
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| − | ln -s /etc/openvpn/easy-rsa/2.0/keys/myServer.crt /etc/openvpn/server.crt
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| − | ln -s /etc/openvpn/easy-rsa/2.0/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/2.0/
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| − | . /etc/openvpn/easy-rsa/2.0/vars
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| − | . /etc/openvpn/easy-rsa/2.0/revoke-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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| − | | |
| − | | |
| − | | |
| − | =Server configuration=
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| − | | |
| − | See attached file “server.conf”
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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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| − | | |
| − | | |
| − |
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| − | =Firewall=
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| − | | |
| − | You can use the following firewall script:
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | MODPROBE=`which modprobe`
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| − | IPTABLES=`which iptables`
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| − | INT_ETH = eth0
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| − | INT_VPN = tun0
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| − | IP_LAN_VPN = 10.8.0.0/24
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| − | | |
| − | # --- #
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| − | # VPN #
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| − | # --- #
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| − | $MODPROBE iptable_nat
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| − | | |
| − | echo " ... Enable NAT features"
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| − | echo 1 > /proc/sys/net/ipv4/ip_forward
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| − | | |
| − | echo " ... Allow all VPN communications (no filter)"
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| − | $IPTABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -j ACCEPT
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| − | $IPTABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -j ACCEPT
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| − | | |
| − | echo " ... Allowing VPN forwarding"
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| − | # Allow forwarding
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| − | $IPTABLES -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
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| − | $IPTABLES -A FORWARD -i $INT_VPN -s $IP_LAN_VPN -j ACCEPT
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| − | $IPTABLES -A FORWARD -j REJECT
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| − | # Allow devices communication $ETH0 <--> tun0
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| − | $IPTABLES -t nat -A POSTROUTING -s $IP_LAN_VPN -o $INT_ETH -j MASQUERADE
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| − | # Forward Established, Related
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| − | $IPTABLES -A FORWARD -s $IP_LAN_VPN -p tcp -m state --state RELATED,ESTABLISHED --sport 1024:65535 --dport 1024:65535 -j ACCEPT
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| − | $IPTABLES -A FORWARD -s $IP_LAN_VPN -p udp -m state --state RELATED,ESTABLISHED --sport 1024:65535 --dport 1024:65535 -j ACCEPT
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| − | | |
| − | Off course, you should also have:
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| − | echo -e " ... Keep$GREEN ESTABLISHED$BLACK connections "
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| − | # Keep established connections
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| − | $IPTABLES -A INPUT -m state --state ESTABLISHED -j ACCEPT
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| − | $IPTABLES -A OUTPUT -m state --state ESTABLISHED -j ACCEPT
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| − | | |
| − | # keep related connections
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| − | echo -e " ... Keep$GREEN RELATED$BLACK connections"
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| − | $IPTABLES -A INPUT -m state --state RELATED -j ACCEPT
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| − | $IPTABLES -A OUTPUT -m state --state RELATED -j ACCEPT
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | | |
| − | =Startup=
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| − | | |
| − | ==Restart services==
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | service openvpn restart
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| − | service firewall restart
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | ==Client Software==
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| − | | |
| − | ===Linux===
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| − | | |
| − | <syntaxhighlight lang="bash">
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| − | apt-get install openssl openssh-server openvpn
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| − | </syntaxhighlight>
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| − | | |
| − | ===Windows===
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| − | | |
| − | On windows, many clients are available.
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| − | The best one for Windows 7 and 8 is: « OpenVPN Connect Client Download for Windows »
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| − | https://openvpn.net/index.php?option=com_content&id=357
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| − | | |
| − | Note: The file must be around 15 Mb.
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| − | | |
| − | ===MacOSX===
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| − | The best VPN client is “tunnelblick”
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| − | http://code.google.com/p/tunnelblick
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| − | * Configuration files are in ~/librairies/openvpn
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| − | * That’s the libraries [“bibliothèque”] folder of the current user
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| − | | |
| − | | |
| − | ==Client files==
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| − | | |
| − | The client requires:
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| − | * Authority of certification ca.cert
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| − | * Client private key client.key
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| − | * Client certificate client.crt
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| − | | |
| − | Then, you can setup client configuration.
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| − | * See “client_conf.ovpn”
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| | | | |
| | | | |
| − | '''Notes:'''
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| − | You have to edit the configuration file.
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| | | | |
| − | * Adjust paths on lines 30-38
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| | | | |
| − | * On Windows you must you the double slash \\
| + | =Next steps= |
| | | | |
| − | * On Linux don’t forget to uncomment the following lines for better security:
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| − | <syntaxhighlight lang="bash">
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| − | # Downgrade privileges after initialization (non-Windows only)
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| − | user nobody
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| − | group nobody
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| − | </syntaxhighlight>
| |
| | | | |
| − | * Linux: depending on your distribution you might need to adjust user / group default name. | + | * [[VPN server]] |
| | + | * [[VPN client]] |
