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Setting-up a Simple CA Using the strongSwan PKI Tool » History » Version 13

Andreas Steffen, 24.12.2009 09:37
Warning against keeping CA key on VPN gateway

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h1. Setting-up a simple CA using strongSwan PKI tool
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This How-To sets up a Certificate Authority using strongSwan [[IpsecPKI|PKI]] tool, keeping it as simple as possible.
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h2. CA certificate
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First, [[IpsecPKIGen|generate]] a private key, the default generates a 2048 bit RSA key:
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<pre>
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ipsec pki --gen > caKey.der
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</pre>
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For a real-world setup, make sure to keep this key private.
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Now [[IpsecPKISelf|self-sign]] a CA certificate using the generated key:
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<pre>
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ipsec pki --self --in caKey.der --dn "C=CH, O=strongSwan, CN=strongSwan CA" --ca > caCert.der
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</pre>
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Adjust the distinguished name to your needs, it will be included in all issued certificates.
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That's it, your CA is ready to issue certificates.
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h2. End entity certificates
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For each peer, generate a private key and [[IpsecPKIIssue|issue]] a certificate using your new CA:
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<pre>
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ipsec pki --gen > peerKey.der
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ipsec pki --pub --in peerKey.der | ipsec pki --issue --cacert caCert.der --cakey caKey.der 
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                                             --dn "C=CH, O=strongSwan, CN=peer" > peerCert.der
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</pre>
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The second command [[IpsecPKIPub|extracts the public key]] and issues a certificate using your CA. Distribute private key and certificate to your peer.
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h2. Install certificates
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Certificates and keys are stored in the [[IpsecDirectory|/etc/ipsec.d/]] subdirectory tree:
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* *[[/IpsecDirectoryPrivate|/etc/ipsec.d/private/]]peerKey.der* holds the private key of the peer.
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* *[[/IpsecDirectoryCerts|/etc/ipsec.d/certs/]]peerCert.der* holds the end entitity certificate of the peer.
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* *[[/IpsecDirectoryCacerts|/etc/ipsec.d/cacerts/]]caCert.der* holds the CA certificate which issued and signed all peer certificates.
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Never store the private key *caKey.der* of the Certification Authority (CA) on a VPN gateway with direct access to the Internet since a theft of this key will completely compromise your PKI.