1 # strongSwan Configuration #
5 strongSwan is an OpenSource IPsec-based VPN solution.
7 This document is just a short introduction of the strongSwan **swanctl** command
8 which uses the modern [**vici**](src/libcharon/plugins/vici/README.md) *Versatile
9 IKE Configuration Interface*. The deprecated **ipsec** command using the legacy
10 **stroke** configuration interface is described [**here**](README_LEGACY.md).
11 For more detailed information consult the man pages and
12 [**our wiki**](https://wiki.strongswan.org).
17 Certificates for users, hosts and gateways are issued by a fictitious
18 strongSwan CA. In our example scenarios the CA certificate `strongswanCert.pem`
19 must be present on all VPN endpoints in order to be able to authenticate the
20 peers. For your particular VPN application you can either use certificates from
21 any third-party CA or generate the needed private keys and certificates yourself
22 with the strongSwan **pki** tool, the use of which will be explained in one of
23 the sections following below.
26 ### Site-to-Site Case ###
28 In this scenario two security gateways _moon_ and _sun_ will connect the
29 two subnets _moon-net_ and _sun-net_ with each other through a VPN tunnel
30 set up between the two gateways:
32 10.1.0.0/16 -- | 192.168.0.1 | === | 192.168.0.2 | -- 10.2.0.0/16
33 moon-net moon sun sun-net
35 Configuration on gateway _moon_:
37 /etc/swanctl/x509ca/strongswanCert.pem
38 /etc/swanctl/x509/moonCert.pem
39 /etc/swanctl/private/moonKey.pem
41 /etc/swanctl/swanctl.conf:
45 remote_addrs = 192.168.0.2
53 id = "C=CH, O=strongSwan, CN=sun.strongswan.org"
57 local_ts = 10.1.0.0/16
58 remote_ts = 10.2.0.0/16
65 Configuration on gateway _sun_:
67 /etc/swanctl/x509ca/strongswanCert.pem
68 /etc/swanctl/x509/sunCert.pem
69 /etc/swanctl/private/sunKey.pem
71 /etc/swanctl/swanctl.conf:
75 remote_addrs = 192.168.0.1
83 id = "C=CH, O=strongSwan, CN=moon.strongswan.org"
87 local_ts = 10.2.0.0/16
88 remote_ts = 10.1.0.0/16
95 The local and remote identities used in this scenario are the
96 *subjectDistinguishedNames* contained in the end entity certificates.
97 The certificates and private keys are loaded into the **charon** daemon with
106 loads the connections defined in `swanctl.conf`. With `start_action = trap` the
107 IPsec connection is automatically set up with the first plaintext payload IP
108 packet wanting to go through the tunnel.
110 ### Host-to-Host Case ###
112 This is a setup between two single hosts which don't have a subnet behind
113 them. Although IPsec transport mode would be sufficient for host-to-host
114 connections we will use the default IPsec tunnel mode.
116 | 192.168.0.1 | === | 192.168.0.2 |
119 Configuration on host _moon_:
121 /etc/swanctl/x509ca/strongswanCert.pem
122 /etc/swanctl/x509/moonCert.pem
123 /etc/swanctl/private/moonKey.pem
125 /etc/swanctl/swanctl.conf:
129 remote_addrs = 192.168.0.2
137 id = "C=CH, O=strongSwan, CN=sun.strongswan.org"
147 Configuration on host _sun_:
149 /etc/swanctl/x509ca/strongswanCert.pem
150 /etc/swanctl/x509/sunCert.pem
151 /etc/swanctl/private/sunKey.pem
153 /etc/swanctl/swanctl.conf:
157 remote_addrs = 192.168.0.1
165 id = "C=CH, O=strongSwan, CN=moon.strongswan.org"
176 ### Roadwarrior Case ###
178 This is a very common case where a strongSwan gateway serves an arbitrary
179 number of remote VPN clients usually having dynamic IP addresses.
181 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x |
184 Configuration on gateway _moon_:
186 /etc/swanctl/x509ca/strongswanCert.pem
187 /etc/swanctl/x509/moonCert.pem
188 /etc/swanctl/private/moonKey.pem
190 /etc/swanctl/swanctl.conf:
197 id = moon.strongswan.org
204 local_ts = 10.1.0.0/16
210 Configuration on roadwarrior _carol_:
212 /etc/swanctl/x509ca/strongswanCert.pem
213 /etc/swanctl/x509/carolCert.pem
214 /etc/swanctl/private/carolKey.pem
216 /etc/swanctl/swanctl.conf:
220 remote_addrs = moon.strongswan.org
224 certs = carolCert.pem
225 id = carol@strongswan.org
229 id = moon.strongswan.org
233 local_ts = 10.1.0.0/16
240 For `remote_addrs` the hostname `moon.strongswan.org` was chosen which will be
241 resolved by DNS at runtime into the corresponding IP destination address.
242 In this scenario the identity of the roadwarrior `carol` is the email address
243 `carol@strongswan.org` which must be included as a *subjectAlternativeName* in
244 the roadwarrior certificate `carolCert.pem`.
247 ### Roadwarrior Case with Virtual IP ###
249 Roadwarriors usually have dynamic IP addresses assigned by the ISP they are
250 currently attached to. In order to simplify the routing from _moon-net_ back
251 to the remote access client _carol_ it would be desirable if the roadwarrior had
252 an inner IP address chosen from a pre-defined pool.
254 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x | -- 10.3.0.1
255 moon-net moon carol virtual IP
257 In our example the virtual IP address is chosen from the address pool
258 `10.3.0.0/16` which can be configured by adding the section
266 to the gateway's `swanctl.conf` from where they are loaded into the **charon**
267 daemon using the command
271 To request an IP address from this pool a roadwarrior can use IKEv1 mode config
272 or IKEv2 configuration payloads. The configuration for both is the same
276 Configuration on gateway _moon_:
278 /etc/swanctl/x509ca/strongswanCert.pem
279 /etc/swanctl/x509/moonCert.pem
280 /etc/swanctl/private/moonKey.pem
282 /etc/swanctl/swanctl.conf:
291 id = moon.strongswan.org
298 local_ts = 10.1.0.0/16
310 Configuration on roadwarrior _carol_:
312 /etc/swanctl/x509ca/strongswanCert.pem
313 /etc/swanctl/x509/carolCert.pem
314 /etc/swanctl/private/carolKey.pem
316 /etc/swanctl/swanctl.conf:
320 remote_addrs = moon.strongswan.org
325 certs = carolCert.pem
326 id = carol@strongswan.org
330 id = moon.strongswan.org
334 local_ts = 10.1.0.0/16
342 ### Roadwarrior Case with EAP Authentication ###
344 This is a very common case where a strongSwan gateway serves an arbitrary
345 number of remote VPN clients which authenticate themselves via a password
346 based *Extended Authentication Protocol* as e.g. *EAP-MD5* or *EAP-MSCHAPv2*.
348 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x |
351 Configuration on gateway _moon_:
353 /etc/swanctl/x509ca/strongswanCert.pem
354 /etc/swanctl/x509/moonCert.pem
355 /etc/swanctl/private/moonKey.pem
357 /etc/swanctl/swanctl.conf:
364 id = moon.strongswan.org
371 local_ts = 10.1.0.0/16
378 The `swanctl.conf` file additionally contains a `secrets` section defining all
383 id = carol@strongswan.org
387 id = dave@strongswan.org
392 Configuration on roadwarrior _carol_:
394 /etc/swanctl/x509ca/strongswanCert.pem
396 /etc/swanctl/swanctl.conf:
400 remote_addrs = moon.strongswan.org
404 id = carol@strongswan.org
408 id = moon.strongswan.org
412 local_ts = 10.1.0.0/16
421 id = carol@strongswan.org
427 ### Roadwarrior Case with EAP Identity ###
429 Often a client EAP identity is exchanged via EAP which differs from the
430 external IKEv2 identity. In this example the IKEv2 identity defaults to
431 the IPv4 address of the client.
433 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x |
436 Configuration on gateway _moon_:
438 /etc/swanctl/x509ca/strongswanCert.pem
439 /etc/swanctl/x509/moonCert.pem
440 /etc/swanctl/private/moonKey.pem
442 /etc/swanctl/swanctl.conf:
449 id = moon.strongswan.org
457 local_ts = 10.1.0.0/16
475 Configuration on roadwarrior _carol_:
477 /etc/swanctl/x509ca/strongswanCert.pem
479 /etc/swanctl/swanctl.conf:
483 remote_addrs = moon.strongswan.org
491 id = moon.strongswan.org
495 local_ts = 10.1.0.0/16
510 ## Generating Certificates and CRLs ##
512 This section is not a full-blown tutorial on how to use the strongSwan **pki**
513 tool. It just lists a few points that are relevant if you want to generate your
514 own certificates and CRLs for use with strongSwan.
517 ### Generating a CA Certificate ###
521 pki --gen --type ed25519 --outform pem > strongswanKey.pem
523 generates an elliptic Edwards-Curve key with a cryptographic strength of 128
524 bits. The corresponding public key is packed into a self-signed CA certificate
525 with a lifetime of 10 years (3652 days)
527 pki --self --ca --lifetime 3652 --in strongswanKey.pem \
528 --dn "C=CH, O=strongSwan, CN=strongSwan Root CA" \
529 --outform pem > strongswanCert.pem
531 which can be listed with the command
533 pki --print --in strongswanCert.pem
535 subject: "C=CH, O=strongSwan, CN=strongSwan Root CA"
536 issuer: "C=CH, O=strongSwan, CN=strongSwan Root CA"
537 validity: not before May 18 08:32:06 2017, ok
538 not after May 18 08:32:06 2027, ok (expires in 3651 days)
539 serial: 57:e0:6b:3a:9a:eb:c6:e0
540 flags: CA CRLSign self-signed
541 subjkeyId: 2b:95:14:5b:c3:22:87:de:d1:42:91:88:63:b3:d5:c1:92:7a:0f:5d
542 pubkey: ED25519 256 bits
543 keyid: a7:e1:6a:3f:e7:6f:08:9d:89:ec:23:92:a9:a1:14:3c:78:a8:7a:f7
544 subjkey: 2b:95:14:5b:c3:22:87:de:d1:42:91:88:63:b3:d5:c1:92:7a:0f:5d
546 If you prefer the CA private key and X.509 certificate to be in binary DER format
547 then just omit the `--outform pem` option. The directory `/etc/swanctl/x509ca`
548 contains all required CA certificates either in binary DER or in Base64 PEM
549 format. Irrespective of the file suffix the correct format will be determined
550 by strongSwan automagically.
553 ### Generating a Host or User End Entity Certificate ###
555 Again we are using the command
557 pki --gen --type ed25519 --outform pem > moonKey.pem
559 to generate an Ed25519 private key for the host `moon`. Alternatively you could
562 pki --gen --type rsa --size 3072 > moonKey.der
564 to generate a traditional 3072 bit RSA key and store it in binary DER format.
565 As an alternative a **TPM 2.0** *Trusted Platform Module* available on every
566 recent Intel platform could be used as a virtual smartcard to securely store an
567 RSA or ECDSA private key. For details, refer to the TPM 2.0
568 [HOWTO](https://wiki.strongswan.org/projects/strongswan/wiki/TpmPlugin).
570 In a next step the command
572 pki --req --type priv --in moonKey.pem \
573 --dn "C=CH, O=strongswan, CN=moon.strongswan.org" \
574 --san moon.strongswan.org --outform pem > moonReq.pem
576 creates a PKCS#10 certificate request that has to be signed by the CA.
577 Through the [multiple] use of the `--san` parameter any number of desired
578 *subjectAlternativeNames* can be added to the request. These can be of the
581 --san sun.strongswan.org # fully qualified host name
582 --san carol@strongswan.org # RFC822 user email address
583 --san 192.168.0.1 # IPv4 address
584 --san fec0::1 # IPv6 address
586 Based on the certificate request the CA issues a signed end entity certificate
587 with the following command
589 pki --issue --cacert strongswanCert.pem --cakey strongswanKey.pem \
590 --type pkcs10 --in moonReq.pem --serial 01 --lifetime 1826 \
591 --outform pem > moonCert.pem
593 If the `--serial` parameter with a hexadecimal argument is omitted then a random
594 serial number is generated. Some third party VPN clients require that a VPN
595 gateway certificate contains the *TLS Server Authentication* Extended Key Usage
596 (EKU) flag which can be included with the following option
600 If you want to use the dynamic CRL fetching feature described in one of the
601 following sections then you may include one or several *crlDistributionPoints*
602 in your end entity certificates using the `--crl` parameter
604 --crl http://crl.strongswan.org/strongswan.crl
605 --crl "ldap://ldap.strongswan.org/cn=strongSwan Root CA, o=strongSwan,c=CH?certificateRevocationList"
607 The issued host certificate can be listed with
609 pki --print --in moonCert.pem
611 subject: "C=CH, O=strongSwan, CN=moon.strongswan.org"
612 issuer: "C=CH, O=strongSwan, CN=strongSwan Root CA"
613 validity: not before May 19 10:28:19 2017, ok
614 not after May 19 10:28:19 2022, ok (expires in 1825 days)
616 altNames: moon.strongswan.org
618 CRL URIs: http://crl.strongswan.org/strongswan.crl
619 authkeyId: 2b:95:14:5b:c3:22:87:de:d1:42:91:88:63:b3:d5:c1:92:7a:0f:5d
620 subjkeyId: 60:9d:de:30:a6:ca:b9:8e:87:bb:33:23:61:19:18:b8:c4:7e:23:8f
621 pubkey: ED25519 256 bits
622 keyid: 39:1b:b3:c2:34:72:1a:01:08:40:ce:97:75:b8:be:ce:24:30:26:29
623 subjkey: 60:9d:de:30:a6:ca:b9:8e:87:bb:33:23:61:19:18:b8:c4:7e:23:8f
625 Usually, a Windows, OSX, Android or iOS based VPN client needs its private key,
626 its host or user certificate and the CA certificate. The most convenient way
627 to load this information is to put everything into a PKCS#12 container:
629 openssl pkcs12 -export -inkey carolKey.pem \
630 -in carolCert.pem -name "carol" \
631 -certfile strongswanCert.pem -caname "strongSwan Root CA" \
634 The strongSwan **pki** tool currently is not able to create PKCS#12 containers
635 so that **openssl** must be used.
638 ### Generating a CRL ###
640 An empty CRL that is signed by the CA can be generated with the command
642 pki --signcrl --cacert strongswanCert.pem --cakey strongswanKey.pem \
643 --lifetime 30 > strongswan.crl
645 If you omit the `--lifetime` option then the default value of 15 days is used.
646 CRLs can either be uploaded to a HTTP or LDAP server or put in binary DER or
647 Base64 PEM format into the `/etc/swanctl/x509crl` directory from where they are
648 loaded into the **charon** daemon with the command
653 ### Revoking a Certificate ###
655 A specific end entity certificate is revoked with the command
657 pki --signcrl --cacert strongswanCert.pem --cakey strongswanKey.pem \
658 --lifetime 30 --lastcrl strongswan.crl \
659 --reason key-compromise --cert moonCert.pem > new.crl
661 Instead of the certificate file (in our example moonCert.pem), the serial number
662 of the certificate to be revoked can be indicated using the `--serial`
663 parameter. The `pki --signcrl --help` command documents all possible revocation
664 reasons but the `--reason` parameter can also be omitted. The content of the new
665 CRL file can be listed with the command
667 pki --print --type crl --in new.crl
669 issuer: "C=CH, O=strongSwan, CN=strongSwan Root CA"
670 update: this on May 19 11:13:01 2017, ok
671 next on Jun 18 11:13:01 2017, ok (expires in 29 days)
673 authKeyId: 2b:95:14:5b:c3:22:87:de:d1:42:91:88:63:b3:d5:c1:92:7a:0f:5d
674 1 revoked certificate:
675 01: May 19 11:13:01 2017, key compromise
678 ### Local Caching of CRLs ###
680 The `strongswan.conf` option
686 activates the local caching of CRLs that were dynamically fetched from an
687 HTTP or LDAP server. Cached copies are stored in `/etc/swanctl/x509crl` using a
688 unique filename formed from the issuer's *subjectKeyIdentifier* and the
691 With the cached copy the CRL is immediately available after startup. When the
692 local copy has become stale, an updated CRL is automatically fetched from one of
693 the defined CRL distribution points during the next IKEv2 authentication.