Project

General

Profile

Setting-up a Simple CA Using the strongSwan PKI Tool » History » Version 29

Noel Kuntze, 25.04.2016 00:25
Link to Simple CA page.

1 27 Tobias Brunner
{{title(Setting-up a Simple CA Using the strongSwan PKI Tool)}}
2 1 Martin Willi
3 27 Tobias Brunner
h1. Setting-up a Simple CA Using the strongSwan PKI Tool
4 23 michael anderl
5 27 Tobias Brunner
{{>toc}}
6 1 Martin Willi
7 27 Tobias Brunner
This how-to sets up a Certificate Authority using strongSwan's [[IpsecPKI|PKI tool]] (available since [[4.3.5]]), keeping it as simple as possible.
8 1 Martin Willi
9 27 Tobias Brunner
h2. CA Certificate
10 27 Tobias Brunner
11 27 Tobias Brunner
First, [[IpsecPKIGen|generate]] a private key, the default generates a 2048 bit RSA key (if this command blocks, refer to [[IpsecPKIGen#Problems-on-Hosts-with-Low-Entropy|this note about hosts with low entropy]]):
12 26 Tobias Brunner
<pre>
13 1 Martin Willi
ipsec pki --gen > caKey.der
14 1 Martin Willi
</pre>
15 27 Tobias Brunner
16 1 Martin Willi
For a real-world setup, make sure to keep this key absolutely private.
17 1 Martin Willi
18 1 Martin Willi
Now [[IpsecPKISelf|self-sign]] a CA certificate using the generated key:
19 1 Martin Willi
<pre>
20 1 Martin Willi
ipsec pki --self --in caKey.der --dn "C=CH, O=strongSwan, CN=strongSwan CA" --ca > caCert.der
21 2 Andreas Steffen
</pre>
22 1 Martin Willi
23 27 Tobias Brunner
Adjust the _distinguished name (DN)_ to your needs, it will be included in all issued certificates.
24 1 Martin Willi
25 27 Tobias Brunner
That's it, your CA is ready to issue end-entity certificates.
26 17 Jean-Michel Pouré
27 27 Tobias Brunner
h2. End Entity Certificates
28 27 Tobias Brunner
29 1 Martin Willi
For *each* peer, i.e. for all VPN clients and VPN gateways in your network, generate an individual private key and [[IpsecPKIIssue|issue]] a matching certificate using your new CA:
30 1 Martin Willi
31 1 Martin Willi
<pre>
32 1 Martin Willi
ipsec pki --gen > peerKey.der
33 1 Martin Willi
34 1 Martin Willi
ipsec pki --pub --in peerKey.der | ipsec pki --issue --cacert caCert.der --cakey caKey.der \
35 1 Martin Willi
                                             --dn "C=CH, O=strongSwan, CN=peer" > peerCert.der
36 1 Martin Willi
</pre>
37 1 Martin Willi
38 27 Tobias Brunner
The second command [[IpsecPKIPub|extracts the public key]] and [[IpsecPKIIssue|issues a certificate]] using your CA.
39 27 Tobias Brunner
 
40 27 Tobias Brunner
If you want to add _subjectAltName_ extensions to your certificates use the _--san_ option (can be provided multiple times), for instance, @--san vpn.strongswan.org@ or @--san peer@strongswan.org@. It is recommended to include the hostname of a gateway as _subjectAltName_ in its certificate.
41 1 Martin Willi
42 27 Tobias Brunner
Depending on your clients there may be additional requirements imposed on gateway certificates, for instance, the [[Win7CertReq|Windows 7 certificate requirements]] or those for [[IOS_(Apple)#Certificate-requirements-for-iOS-interoperability|iOS and Mac OS X clients]].
43 27 Tobias Brunner
44 27 Tobias Brunner
Distribute each private key and matching certificate to the corresponding peer.
45 27 Tobias Brunner
46 27 Tobias Brunner
h2. Certificate Revocation Lists (CRL)
47 27 Tobias Brunner
48 27 Tobias Brunner
In case end entity certificates have to be revoked, Certificate Revocation Lists (CRLs) may be generated with the [[IpsecPkiSigncrl|ipsec pki --signcrl]] command:
49 27 Tobias Brunner
50 27 Tobias Brunner
<pre>
51 27 Tobias Brunner
ipsec pki --signcrl --cacert caCert.der --cakey caKey.der --reason superseded --cert peerCert.der > crl.der
52 27 Tobias Brunner
</pre>
53 27 Tobias Brunner
54 27 Tobias Brunner
The certificate given with @--cacert@ must be either a CA certificate or a certificate with the _crlSign_ extended key usage (@--flag crlSign@).
55 27 Tobias Brunner
56 27 Tobias Brunner
When [[IpsecPKIIssue|issuing certificates]] an URL to a CRL may be added with the @--crl@ argument.
57 27 Tobias Brunner
58 1 Martin Willi
h2. Install certificates
59 1 Martin Willi
60 1 Martin Willi
On *each* peer store the following certificates and keys in the [[IpsecDirectory|/etc/ipsec.d/]] subdirectory tree:
61 4 Jean-Michel Pouré
62 1 Martin Willi
* *[[/IpsecDirectoryPrivate|/etc/ipsec.d/private/]]peerKey.der* holds the private key of the given peer.
63 18 Andreas Steffen
* *[[/IpsecDirectoryCerts|/etc/ipsec.d/certs/]]peerCert.der* holds the end entitity certificate of the given peer.
64 5 Jean-Michel Pouré
* *[[/IpsecDirectoryCacerts|/etc/ipsec.d/cacerts/]]caCert.der* holds the CA certificate which issued and signed all peer certificates.
65 19 Andreas Steffen
66 19 Andreas Steffen
Never store the private key *caKey.der* of the Certification Authority (CA) on a host with constant direct access to the Internet (e.g. a VPN gateway), since a theft of this master signing key will completely compromise your PKI.
67 27 Tobias Brunner
68 27 Tobias Brunner
Optionally, the CRL may be stored in the following directory (if the certificate contains an URL to a CRL, it will be fetched on demand):
69 27 Tobias Brunner
70 27 Tobias Brunner
* *[[/IpsecDirectoryCrls|/etc/ipsec.d/crls/]]crl.der* holds the CRL signed by the CA (or a certificate containing the _crlSign_ EKU).
71 28 Carl-Daniel Hailfinger
72 28 Carl-Daniel Hailfinger
h3. Install certificates in Android
73 28 Carl-Daniel Hailfinger
74 28 Carl-Daniel Hailfinger
Android needs certificates in PKCS#12 format. You can convert the certificates/keys created above to PKCS#12:
75 28 Carl-Daniel Hailfinger
76 28 Carl-Daniel Hailfinger
<pre>
77 28 Carl-Daniel Hailfinger
openssl x509 -inform der -outform pem -in caCert.der -out caCert.pem
78 28 Carl-Daniel Hailfinger
openssl x509 -inform der -outform pem -in peerCert.der -out peerCert.pem
79 28 Carl-Daniel Hailfinger
openssl rsa -inform der -outform pem -in peerKey.der -out peerKey.pem
80 28 Carl-Daniel Hailfinger
openssl pkcs12 -in peerCert.pem -inkey peerKey.pem -certfile caCert.pem -export -out peer.p12
81 28 Carl-Daniel Hailfinger
</pre>
82 28 Carl-Daniel Hailfinger
83 28 Carl-Daniel Hailfinger
peer.p12 can be imported in Android and contains everything needed by the StrongSwan client.