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@@ -1,82 +1,35 @@ - ---------------------------- - strongSwan - Configuration - ---------------------------- - - -Contents --------- - - 1. Overview - 2. Quickstart - 2.1 Site-to-Site case - 2.2 Host-to-Host case - 2.3 Roadwarrior case - 2.4 Roadwarrior case with virtual IP - 3. Generating X.509 certificates and CRLs - 3.1 Generating a CA certificate - 3.2 Generating a host or user certificate - 3.3 Generating a CRL - 3.4 Revoking a certificate - 4. Configuring the connections - ipsec.conf - 4.1 Configuring my side - 4.2 Multiple certificates - 4.3 Configuring the peer side using CA certificates - 4.4 Handling Virtual IPs and wildcard subnets - 4.5 Protocol and port selectors - 4.6 IPsec policies based on wildcards - 4.7 IPsec policies based on CA certificates - 5. Configuring certificates and CRLs - 5.1 Installing CA certificates - 5.2 Installing optional Certificate Revocation Lists (CRLs) - 5.3 Dynamic update of certificates and CRLs - 5.4 Local caching of CRLs - 5.5 Online Certificate Status Protocol (OCSP) - 5.6 CRL policy - 5.7 Configuring the peer side using locally stored certificates - 6. Configuring the private keys - ipsec.secrets - 6.1 Loading private key files in PKCS#1 format - 6.2 Entering passphrases interactively - 6.3 Multiple private keys - 7. Configuring CA properties - ipsec.conf - 8. Monitoring functions - 9. Firewall support functions - 9.1 Environment variables in the updown script - 9.2 Automatic insertion and deletion of iptables firewall rules - - -1. Overview - -------- - -strongSwan is an OpenSource IPsec solution for Unix based operating systems. +# strongSwan Configuration # + +## Overview ## + +strongSwan is an OpenSource IPsec-based VPN solution. This document is just a short introduction, for more detailed information -consult the manual pages and our wiki: +consult the man pages and [**our wiki**](http://wiki.strongswan.org). - http://wiki.strongswan.org +## Quickstart ## -2. Quickstart - ---------- +In the following examples we assume, for reasons of clarity, that **left** +designates the **local** host and that **right** is the **remote** host. -In the following examples we assume for reasons of clarity that left designates -the local host and that right is the remote host. Certificates for users, -hosts and gateways are issued by a fictitious strongSwan CA. How to generate -private keys and certificates using OpenSSL or the strongSwan PKI tool will be -explained in section 3. The CA certificate "strongswanCert.pem" must be present -on all VPN end points in order to be able to authenticate the peers. +Certificates for users, hosts and gateways are issued by a fictitious +strongSwan CA. How to generate private keys and certificates using OpenSSL or +the strongSwan PKI tool will be explained in one of the sections below. +The CA certificate `strongswanCert.pem` must be present on all VPN endpoints +in order to be able to authenticate the peers. -2.1 Site-to-site case - ----------------- +### Site-to-site case ### -In this scenario two security gateways moon and sun will connect the -two subnets moon-net and sun-net with each other through a VPN tunnel +In this scenario two security gateways _moon_ and _sun_ will connect the +two subnets _moon-net_ and _sun-net_ with each other through a VPN tunnel set up between the two gateways: 10.1.0.0/16 -- | 192.168.0.1 | === | 192.168.0.2 | -- 10.2.0.0/16 moon-net moon sun sun-net -Configuration on gateway moon: +Configuration on gateway _moon_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -96,7 +49,7 @@ Configuration on gateway moon: rightid="C=CH, O=strongSwan, CN=sun.strongswan.org" auto=start -Configuration on gateway sun: +Configuration on gateway _sun_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -117,8 +70,7 @@ Configuration on gateway sun: auto=start -2.2 Host-to-host case - ----------------- +### Host-to-host case ### This is a setup between two single hosts which don't have a subnet behind them. Although IPsec transport mode would be sufficient for host-to-host @@ -127,7 +79,7 @@ connections we will use the default IPsec tunnel mode. | 192.168.0.1 | === | 192.168.0.2 | moon sun -Configuration on host moon: +Configuration on host _moon_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -145,7 +97,7 @@ Configuration on host moon: rightid="C=CH, O=strongSwan, CN=sun.strongswan.org" auto=start -Configuration on host sun: +Configuration on host _sun_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -164,8 +116,7 @@ Configuration on host sun: auto=start -2.3 Roadwarrior case - ---------------- +### Roadwarrior case ### This is a very common case where a strongSwan gateway serves an arbitrary number of remote VPN clients usually having dynamic IP addresses. @@ -173,7 +124,7 @@ number of remote VPN clients usually having dynamic IP addresses. 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x | moon-net moon carol -Configuration on gateway moon: +Configuration on gateway _moon_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -191,7 +142,7 @@ Configuration on gateway moon: right=%any auto=add -Configuration on roadwarrior carol: +Configuration on roadwarrior _carol_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -211,29 +162,28 @@ Configuration on roadwarrior carol: auto=start -2.6 Roadwarrior case with virtual IP - -------------------------------- +### Roadwarrior case with virtual IP ### Roadwarriors usually have dynamic IP addresses assigned by the ISP they are -currently attached to. In order to simplify the routing from moon-net back -to the remote access client carol it would be desirable if the roadwarrior had -an inner IP address chosen from a pre-assigned pool. +currently attached to. In order to simplify the routing from _moon-net_ back +to the remote access client _carol_ it would be desirable if the roadwarrior had +an inner IP address chosen from a pre-defined pool. 10.1.0.0/16 -- | 192.168.0.1 | === | x.x.x.x | -- 10.3.0.1 moon-net moon carol virtual IP In our example the virtual IP address is chosen from the address pool -10.3.0.0/16 which can be configured by adding the parameter +`10.3.0.0/16` which can be configured by adding the parameter rightsourceip=10.3.0.0/16 -to the gateway's ipsec.conf. To request an IP address from this pool a +to the gateway's `ipsec.conf`. To request an IP address from this pool a roadwarrior can use IKEv1 mode config or IKEv2 configuration payloads. The configuration for both is the same leftsourceip=%config -Configuration on gateway moon: +Configuration on gateway _moon_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -252,7 +202,7 @@ Configuration on gateway moon: rightsourceip=10.3.0.0/16 auto=add -Configuration on roadwarrior carol: +Configuration on roadwarrior _carol_: /etc/ipsec.d/cacerts/strongswanCert.pem @@ -273,29 +223,28 @@ Configuration on roadwarrior carol: auto=start -3. Generating certificates and CRLs - -------------------------------- +## Generating certificates and CRLs ## This section is not a full-blown tutorial on how to use OpenSSL or the strongSwan PKI tool. It just lists a few points that are relevant if you want to generate your own certificates and CRLs for use with strongSwan. -3.1 Generating a CA certificate - --------------------------- +### Generating a CA certificate ### The OpenSSL statement openssl req -x509 -days 1460 -newkey rsa:4096 \ -keyout strongswanKey.pem -out strongswanCert.pem -creates a 4096 bit RSA private key strongswanKey.pem and a self-signed CA -certificate strongswanCert.pem with a validity of 4 years (1460 days). +creates a 4096 bit RSA private key `strongswanKey.pem` and a self-signed CA +certificate `strongswanCert.pem` with a validity of 4 years (1460 days). openssl x509 -in cert.pem -noout -text -lists the properties of a X.509 certificate cert.pem. It allows you to verify -whether the configuration defaults in openssl.cnf have been inserted correctly. +lists the properties of a X.509 certificate `cert.pem`. It allows you to verify +whether the configuration defaults in `openssl.cnf` have been inserted +correctly. If you prefer the CA certificate to be in binary DER format then the following command achieves this transformation: @@ -311,28 +260,27 @@ The statements ipsec pki --print --in strongswanCert.der achieve about the same with the strongSwan PKI tool. Unlike OpenSSL the tool -stores keys and certificates in the binary DER format by default. The --outform -option may be used to write PEM encoded files. +stores keys and certificates in the binary DER format by default. +The `--outform` option may be used to write PEM encoded files. -The directory /etc/ipsec.d/cacerts contains all required CA certificates either -in binary DER or in base64 PEM format, irrespective of the file suffix the -correct format will be determined. +The directory `/etc/ipsec.d/cacerts` contains all required CA certificates +either in binary DER or in Base64 PEM format, irrespective of the file suffix +the correct format will be determined. -3.2 Generating a host or user certificate - ------------------------------------- +### Generating a host or user certificate ### The OpenSSL statement openssl req -newkey rsa:2048 -keyout hostKey.pem \ -out hostReq.pem -generates a 2048 bit RSA private key hostKey.pem and a certificate request -hostReq.pem which has to be signed by the CA. +generates a 2048 bit RSA private key `hostKey.pem` and a certificate request +`hostReq.pem` which has to be signed by the CA. -If you want to add a subjectAltName field to the host certificate you must edit -the OpenSSL configuration file openssl.cnf and add the following line in the -[ usr_cert ] section: +If you want to add a _subjectAltName_ field to the host certificate you must +edit the OpenSSL configuration file `openssl.cnf` and add the following line in +the `[ usr_cert ]` section: subjectAltName=DNS:moon.strongswan.org @@ -340,7 +288,7 @@ if you want to identify the host by its Fully Qualified Domain Name (FQDN), or subjectAltName=IP:192.168.0.1 -if you want the ID to be of type IPV4_ADDR. Of course you could include both +if you want the ID to be of type _IPV4_ADDR_. Of course you could include both ID types with subjectAltName=DNS:moon.strongswan.org,IP:192.168.0.1 @@ -348,7 +296,7 @@ ID types with but the use of an IP address for the identification of a host should be discouraged anyway. -For user certificates the appropriate ID type is RFC822_ADDR which can be +For user certificates the appropriate ID type is _RFC822_ADDR_ which can be specified as subjectAltName=email:carol@strongswan.org @@ -361,15 +309,15 @@ Now the certificate request can be signed by the CA with the command openssl ca -in hostReq.pem -days 730 -out hostCert.pem -notext -If you omit the -days option then the default_days value (365 days) specified -in openssl.cnf is used. The -notext option avoids that a human readable -listing of the certificate is prepended to the base64 encoded certificate -body. +If you omit the `-days` option then the `default_days` value (365 days) +specified in `openssl.cnf` is used. The `-notext` option avoids that a human +readable listing of the certificate is prepended to the Base64 encoded +certificate body. -If you want to use the dynamic CRL fetching feature described in section 4.7 -then you may include one or several crlDistributionPoints in your end -certificates. This can be done in the [ usr_cert ] section of the openssl.cnf -configuration file: +If you want to use the dynamic CRL fetching feature described in one of the +following sections then you may include one or several _crlDistributionPoints_ +in your end certificates. This can be done in the `[ usr_cert ]` section of the +`openssl.cnf` configuration file: crlDistributionPoints=@crl_dp @@ -394,11 +342,11 @@ Again the statements --san moon.strongswan.org --san 192.168.0.1 \ --crl http://crl.strongswan.org/strongswan.crl > moonCert.der -do something thing similar using the strongSwan PKI tool. +do something similar using the strongSwan PKI tool. Usually, a Windows or Mac OS X (or iOS) based VPN client needs its private key, -its host or user certificate, and the CA certificate. The most convenient way -to load this information is to put everything into a PKCS#12 file: +its host or user certificate, and the CA certificate. The most convenient way +to load this information is to put everything into a PKCS#12 container: openssl pkcs12 -export -inkey carolKey.pem \ -in carolCert.pem -name "carol" \ @@ -406,32 +354,30 @@ to load this information is to put everything into a PKCS#12 file: -out carolCert.p12 -3.3 Generating a CRL - ---------------- +### Generating a CRL ### An empty CRL that is signed by the CA can be generated with the command openssl ca -gencrl -crldays 15 -out crl.pem -If you omit the -crldays option then the default_crl_days value (30 days) -specified in openssl.cnf is used. +If you omit the `-crldays` option then the `default_crl_days` value (30 days) +specified in `openssl.cnf` is used. If you prefer the CRL to be in binary DER format then this conversion can be achieved with openssl crl -in crl.pem -outform DER -out cert.crl -The strongSwan PKI tool provides the ipsec pki --signcrl command to sign CRLs. +The strongSwan PKI tool provides the `--signcrl` command to sign CRLs. -The directory /etc/ipsec.d/crls contains all CRLs either in binary DER -or in base64 PEM format, irrespective of the file suffix the correct format +The directory `/etc/ipsec.d/crls` contains all CRLs either in binary DER +or in Base64 PEM format, irrespective of the file suffix the correct format will be determined. -3.4 Revoking a certificate - ---------------------- +### Revoking a certificate ### -A specific host certificate stored in the file host.pem is revoked with the +A specific host certificate stored in the file `host.pem` is revoked with the command openssl ca -revoke host.pem @@ -444,30 +390,28 @@ The content of the CRL file can be listed with the command openssl crl -in crl.pem -noout -text -in the case of a base64 CRL, or alternatively for a CRL in DER format +in the case of a Base64 CRL, or alternatively for a CRL in DER format openssl crl -inform DER -in cert.crl -noout -text -Again the ipsec pki --signcrl command may be used to create new CRLs containing -additional certificates. +Again the `--signcrl` command of the strongSwan PKI tool may also be used to +create new CRLs containing additional certificates. -4. Configuring the connections - ipsec.conf - ---------------------------------------- +## Configuring the connections - ipsec.conf ## -4.1 Configuring my side - ------------------- +### Configuring my side ### -Usually the local side is the same for all connections. Therefore it makes +Usually the **local** side is the same for all connections. Therefore it makes sense to put the definitions characterizing the strongSwan security gateway into -the conn %default section of the configuration file /etc/ipsec.conf. If we -assume throughout this document that the strongSwan security gateway is left and -the peer is right then we can write +the `conn %default` section of the configuration file `/etc/ipsec.conf`. If we +assume throughout this document that the strongSwan security gateway is **left** +and the peer is **right** then we can write -conn %default - leftcert=moonCert.pem - # load connection definitions automatically - auto=add + conn %default + leftcert=moonCert.pem + # load connection definitions automatically + auto=add The X.509 certificate by which the strongSwan security gateway will authenticate itself by sending it in binary form to its peers as part of the Internet Key @@ -475,23 +419,16 @@ Exchange (IKE) is specified in the line leftcert=moonCert.pem -The certificate can either be stored in base64 PEM-format or in the binary +The certificate can either be stored in Base64 PEM-format or in the binary DER-format. Irrespective of the file suffix the correct format will be -determined. Therefore - - leftcert=moonCert.der - -or - - leftcert=moonCert.cer - +determined. Therefore `leftcert=moonCert.der` or `leftcert=moonCert.cer` would also be valid alternatives. When using relative pathnames as in the examples above, the certificate files -must be stored in in the directory /etc/ipsec.d/certs. In order to distinguish -strongSwan's own certificates from locally stored trusted peer certificates -(see section 5.5 for details), they could also be stored in a subdirectory -below /etc/ipsec.d/certs as e.g. in +must be stored in in the directory `/etc/ipsec.d/certs`. In order to +distinguish strongSwan's own certificates from locally stored trusted peer +certificates (see below for details), they could also be stored in a +subdirectory below `/etc/ipsec.d/certs` as e.g. in leftcert=mycerts/moonCert.pem @@ -502,173 +439,142 @@ Absolute pathnames are also possible as in As an ID for the VPN gateway we recommend the use of a Fully Qualified Domain Name (FQDN) of the form -conn rw - right=%any - leftid=@moon.strongswan.org + conn rw + right=%any + leftid=moon.strongswan.org -Important: When a FQDN identifier is used it must be explicitly included as a -so called subjectAltName of type dnsName (DNS:) in the certificate indicated -by leftcert. For details on how to generate certificates with subjectAltNames, -please refer to section 3.2. +**Important**: When a FQDN identifier is used it must be explicitly included as +a so called _subjectAltName_ of type _dnsName_ (`DNS:`) in the certificate +indicated by `leftcert`. For details on how to generate certificates with +_subjectAltNames_, please refer to the sections above. -If you don't want to mess with subjectAltNames, you can use the certificate's -Distinguished Name (DN) instead, which is an identifier of type DER_ASN1_DN +If you don't want to mess with _subjectAltNames_, you can use the certificate's +Distinguished Name (DN) instead, which is an identifier of type _DER_ASN1_DN_ and which can be written e.g. in the LDAP-type format -conn rw - right=%any - leftid="C=CH, O=strongSwan, CN=moon.strongswan.org" + conn rw + right=%any + leftid="C=CH, O=strongSwan, CN=moon.strongswan.org" -Since the subject's DN is part of the certificate, the leftid does not have to +Since the subject's DN is part of the certificate, the `leftid` does not have to be declared explicitly. Thus the entry -conn rw - right=%any + conn rw + right=%any -automatically assumes the subject DN of leftcert to be the host ID. +automatically assumes the subject DN of `leftcert` to be the host ID. -4.2 Multiple certificates - --------------------- +### Multiple certificates ### strongSwan supports multiple local host certificates and corresponding RSA private keys: -conn rw1 - right=%any - rightid=@peer1.domain1 - leftcert=myCert1.pem - # leftid is DN of myCert1 + conn rw1 + right=%any + rightid=peer1.domain1 + leftcert=myCert1.pem + # leftid is DN of myCert1 -conn rw2 - right=%any - rightid=@peer2.domain2 - leftcert=myCert2.pem - # leftid is DN of myCert2 + conn rw2 + right=%any + rightid=peer2.domain2 + leftcert=myCert2.pem + # leftid is DN of myCert2 -When peer1 initiates a connection then strongSwan will send myCert1 and will -sign with myKey1 defined in /etc/ipsec.secrets (see section 6.2) whereas -myCert2 and myKey2 will be used in a connection setup started from peer2. +When _peer1_ initiates a connection then strongSwan will send _myCert1_ and will +sign with _myKey1_ defined in `/etc/ipsec.secrets` (see below) whereas +_myCert2_ and _myKey2_ will be used in a connection setup started from _peer2_. -4.3 Configuring the peer side using CA certificates - ----------------------------------------------- +### Configuring the peer side using CA certificates ### Now we can proceed to define our connections. In many applications we might have dozens of road warriors connecting to a central strongSwan security gateway. The following most simple statement: -conn rw - right=%any + conn rw + right=%any -defines the general roadwarrior case. The line right=%any literally means that -any IPsec peer is accepted, regardless of its current IP source address and its -ID, as long as the peer presents a valid X.509 certificate signed by a CA the -strongSwan security gateway puts explicit trust in. Additionally, the signature -during IKE gives proof that the peer is in possession of the private RSA key -matching the public key contained in the transmitted certificate. +defines the general roadwarrior case. The line `right=%any` literally means +that any IPsec peer is accepted, regardless of its current IP source address and +its ID, as long as the peer presents a valid X.509 certificate signed by a CA +the strongSwan security gateway puts explicit trust in. Additionally, the +signature during IKE gives proof that the peer is in possession of the private +key matching the public key contained in the transmitted certificate. The ID by which a peer is identifying itself during IKE can by any of the ID -types IPV[46]_ADDR, FQDN, RFC822_ADDR or DER_ASN1_DN. If one of the first -three ID types is used, then the accompanying X.509 certificate of the peer -must contain a matching subjectAltName field of the type ipAddress (IP:), -dnsName (DNS:) or rfc822Name (email:), respectively. With the fourth type -DER_ASN1_DN the identifier must completely match the subject field of the -peer's certificate. One of the two possible representations of a +types _IPV[46]_ADDR_, _FQDN_, _RFC822_ADDR_ or _DER_ASN1_DN_. If one of the +first three ID types is used, then the accompanying X.509 certificate of the +peer must contain a matching _subjectAltName_ field of the type _ipAddress_ +(`IP:`), _dnsName_ (`DNS:`) or _rfc822Name_ (`email:`), respectively. With the +fourth type, _DER_ASN1_DN_, the identifier must completely match the subject +field of the peer's certificate. One of the two possible representations of a Distinguished Name (DN) is the LDAP-type format rightid="C=CH, O=strongSwan IPsec, CN=sun.strongswan.org" Additional whitespace can be added everywhere as desired since it will be -automatically eliminated by the X.509 parser. An exception is the single -whitespace between individual words, like e.g. in strongSwan IPsec, which is -preserved by the parser. +automatically eliminated by the parser. An exception is the single whitespace +between individual words, like e.g. in `strongSwan IPsec`, which is preserved. The Relative Distinguished Names (RDNs) can alternatively be separated by a -slash '/' instead of a comma ',' +slash `/` instead of a comma `,` rightid="/C=CH/O=strongSwan IPsec/CN=sun.strongswan.org" This is the representation extracted from the certificate by the OpenSSL -command line option +`-subject` command line option openssl x509 -in sunCert.pem -noout -subject The following RDNs are supported by strongSwan -+-------------------------------------------------------+ -| DC Domain Component | -|-------------------------------------------------------| -| C Country | -|-------------------------------------------------------| -| ST State or province | -|-------------------------------------------------------| -| L Locality or town | -|-------------------------------------------------------| -| O Organization | -|-------------------------------------------------------| -| OU Organizational Unit | -|-------------------------------------------------------| -| CN Common Name | -|-------------------------------------------------------| -| ND NameDistinguisher, used with CN | -|-------------------------------------------------------| -| N Name | -|-------------------------------------------------------| -| G Given name | -|-------------------------------------------------------| -| S Surname | -|-------------------------------------------------------| -| I Initials | -|-------------------------------------------------------| -| T Personal title | -|-------------------------------------------------------| -| E E-mail | -|-------------------------------------------------------| -| Email E-mail | -|-------------------------------------------------------| -| emailAddress E-mail | -|-------------------------------------------------------| -| SN Serial number | -|-------------------------------------------------------| -| serialNumber Serial number | -|-------------------------------------------------------| -| D Description | -|-------------------------------------------------------| -| ID X.500 Unique Identifier | -|-------------------------------------------------------| -| UID User ID | -|-------------------------------------------------------| -| TCGID [Siemens] Trust Center Global ID | -|-------------------------------------------------------| -| UN Unstructured Name | -|-------------------------------------------------------| -| unstructuredName Unstructured Name | -|-------------------------------------------------------| -| UA Unstructured Address | -|-------------------------------------------------------| -| unstructuredAddress Unstructured Address | -|-------------------------------------------------------| -| EN Employee Number | -|-------------------------------------------------------| -| employeeNumber Employee Number | -|-------------------------------------------------------| -| dnQualifier DN Qualifier | -+-------------------------------------------------------+ +| Name | Description | +|--------------------|----------------------------------| +| DC | Domain Component | +| C | Country | +| ST | State or province | +| L | Locality or town | +| O | Organization | +| OU | Organizational Unit | +| CN | Common Name | +| ND | NameDistinguisher, used with CN | +| N | Name | +| G | Given name | +| S | Surname | +| I | Initials | +| T | Personal title | +| E | E-mail | +| Email | E-mail | +| emailAddress | E-mail | +| SN | Serial number | +| serialNumber | Serial number | +| D | Description | +| ID | X.500 Unique Identifier | +| UID | User ID | +| TCGID | [Siemens] Trust Center Global ID | +| UN | Unstructured Name | +| unstructuredName | Unstructured Name | +| UA | Unstructured Address | +| unstructuredAddress| Unstructured Address | +| EN | Employee Number | +| employeeNumber | Employee Number | +| dnQualifier | DN Qualifier | With the roadwarrior connection definition listed above, an IPsec SA for -the strongSwan security gateway moon.strongswan.org itself can be established. -If any roadwarrior should be able to reach e.g. the two subnets 10.1.0.0/24 -and 10.1.3.0/24 behind the security gateway then the following connection +the strongSwan security gateway `moon.strongswan.org` itself can be established. +If the roadwarriors should be able to reach e.g. the two subnets `10.1.0.0/24` +and `10.1.3.0/24` behind the security gateway then the following connection definitions will make this possible -conn rw1 - right=%any - leftsubnet=10.1.0.0/24 + conn rw1 + right=%any + leftsubnet=10.1.0.0/24 -conn rw3 - right=%any - leftsubnet=10.1.3.0/24 + conn rw3 + right=%any + leftsubnet=10.1.3.0/24 For IKEv2 connections this can even be simplified by using @@ -677,199 +583,192 @@ For IKEv2 connections this can even be simplified by using If not all peers in possession of a X.509 certificate signed by a specific certificate authority shall be given access to the Linux security gateway, then either a subset of them can be barred by listing the serial numbers of -their certificates in a certificate revocation list (CRL) as specified in -section 5.2 or as an alternative, access can be controlled by explicitly -putting a roadwarrior entry for each eligible peer into ipsec.conf: +their certificates in a certificate revocation list (CRL) or as an alternative, +access can be controlled by explicitly putting a roadwarrior entry for each +eligible peer into `ipsec.conf`: -conn sun - right=%any - rightid=@sun.strongswan.org + conn sun + right=%any + rightid=sun.strongswan.org -conn carol - right=%any - rightid=carol@strongswan.org + conn carol + right=%any + rightid=carol@strongswan.org -conn dave - right=%any - rightid="C=CH, O=strongSwan, CN=dave@strongswan.org" + conn dave + right=%any + rightid="C=CH, O=strongSwan, CN=dave@strongswan.org" When the IP address of a peer is known to be stable, it can be specified as well. This entry is mandatory when the strongSwan host wants to act as the initiator of an IPsec connection. -conn sun - right=192.168.0.2 - rightid=@sun.strongswan.org + conn sun + right=192.168.0.2 + rightid=sun.strongswan.org -conn carol - right=192.168.0.100 - rightid=carol@strongswan.org + conn carol + right=192.168.0.100 + rightid=carol@strongswan.org -conn dave - right=192.168.0.200 - rightid="C=CH, O=strongSwan, CN=dave@strongswan.org" + conn dave + right=192.168.0.200 + rightid="C=CH, O=strongSwan, CN=dave@strongswan.org" -conn venus - right=192.168.0.50 + conn venus + right=192.168.0.50 -In the last example the ID types FQDN, RFC822_ADDR, DER_ASN1_DN and IPV4_ADDR, -respectively, were used. Of course all connection definitions presented so far -have included the lines in the conn %defaults section, comprising among other -a leftcert entry. +In the last example the ID types _FQDN_, _RFC822_ADDR_, _DER_ASN1_DN_ and +_IPV4_ADDR_, respectively, were used. Of course all connection definitions +presented so far have included the lines in the `conn %defaults` section, +comprising among other a `leftcert` entry. -4.4 Handling Virtual IPs and narrowing - ---------------------------------- +### Handling Virtual IPs and narrowing ### -Often roadwarriors are behind NAT-boxes with IPsec passthrough, which causes -the inner IP source address of an IPsec tunnel to be different from the -outer IP source address usually assigned dynamically by the ISP. -Whereas the varying outer IP address can be handled by the right=%any -construct, the inner IP address or subnet must always be declared in a -connection definition. Therefore for the three roadwarriors rw1 to rw3 -connecting to a strongSwan security gateway the following entries are -required in /etc/ipsec.conf: +Often roadwarriors are behind NAT-boxes, which causes the inner IP source +address of an IPsec tunnel to be different from the outer IP source address +usually assigned dynamically by the ISP. Whereas the varying outer IP address +can be handled by the `right=%any` construct, the inner IP address or subnet +must always be declared in a connection definition. Therefore for the three +roadwarriors _rw1_ to _rw3_ connecting to a strongSwan security gateway the +following entries are required in `/etc/ipsec.conf`: -conn rw1 - right=%any - righsubnet=10.4.0.5/32 + conn rw1 + right=%any + righsubnet=10.4.0.5/32 -conn rw2 - right=%any - rightsubnet=10.4.0.47/32 + conn rw2 + right=%any + rightsubnet=10.4.0.47/32 -conn rw3 - right=%any - rightsubnet=10.4.0.128/28 + conn rw3 + right=%any + rightsubnet=10.4.0.128/28 Because the charon daemon uses narrowing (even for IKEv1) these three entries can be reduced to the single connection definition -conn rw - right=%any - rightsubnet=10.4.0.0/24 + conn rw + right=%any + rightsubnet=10.4.0.0/24 Any host will be accepted (of course after successful authentication based on the peer's X.509 certificate only) if it declares a client subnet lying totally -within the brackets defined by the subnet definition (in our example -10.4.0.0/24). +within the boundaries defined by the subnet definition (in our example +`10.4.0.0/24`). This strongSwan feature can also be helpful with VPN clients getting a dynamically assigned inner IP from a DHCP server located on the NAT router box. +Since the private IP address of roadwarriors will often not be known they are +usually assigned virtual IPs from a predefined pool. This also makes routing +traffic back to the roadwarriors easier. For example, to assign each client an +IP address from the `10.5.0.0/24` subnet `conn rw` can be defined as -4.5 Protocol and Port Selectors - --------------------------- + conn rw + right=%any + rightsourceip=10.5.0.0/24 -strongSwan offer the possibility to restrict the protocol and optionally the -ports in an IPsec SA using the rightprotoport and leftprotoport parameters. -Some examples: +### Protocol and Port Selectors ### -conn icmp - right=%any - rightprotoport=icmp - leftid=@moon.strongswan.org - leftprotoport=icmp - -conn http - right=%any - rightprotoport=6 - leftid=@moon.strongswan.org - leftprotoport=6/80 - -conn l2tp # with port wildcard for Mac OS X Panther interoperability - right=%any - rightprotoport=17/%any - leftid=@moon.strongswan.org - leftprotoport=17/1701 - -conn dhcp - right=%any - rightprotoport=udp/bootpc - leftid=@moon.strongswan.org - leftsubnet=0.0.0.0/0 #allows DHCP discovery broadcast - leftprotoport=udp/bootps - rekey=no - keylife=20s - rekeymargin=10s - auto=add +strongSwan offers the possibility to restrict the protocol and optionally the +ports in an IPsec SA using the `rightprotoport` and `leftprotoport` parameters. +For IKEv2 multiple such restrictions can also be configured in +`leftsubnet` and `rightsubnet`. -Protocols and ports can be designated either by their numerical values -or by their acronyms defined in /etc/services. - - ipsec status +Some examples: -shows the following connection definitions: + conn icmp + right=%any + rightprotoport=icmp + leftid=moon.strongswan.org + leftprotoport=icmp + + conn http + right=%any + rightprotoport=6 + leftid=moon.strongswan.org + leftprotoport=6/80 + + conn l2tp + right=%any + # with port wildcard for interoperability with certain L2TP clients + rightprotoport=17/%any + leftid=moon.strongswan.org + leftprotoport=17/1701 + + conn dhcp + right=%any + rightprotoport=udp/bootpc + leftid=moon.strongswan.org + leftsubnet=0.0.0.0/0 #allows DHCP discovery broadcast + leftprotoport=udp/bootps -"icmp": 192.168.0.1[@moon.strongswan.org]:1/0...%any:1/0 -"http": 192.168.0.1[@moon.strongswan.org]:6/80...%any:6/0 -"l2tp": 192.168.0.1[@moon.strongswan.org]:17/1701...%any:17/%any -"dhcp": 0.0.0.0/0===192.168.0.1[@moon.strongswan.org]:17/67...%any:17/68 +Protocols and ports can be designated either by their numerical values +or by their acronyms defined in `/etc/services`. Based on the protocol and port selectors appropriate policies will be set up, so that only the specified payload types will pass through the IPsec tunnel. -4.6 IPsec policies based on wildcards - --------------------------------- +### IPsec policies based on wildcards ### In large VPN-based remote access networks there is often a requirement that access to the various parts of an internal network must be granted selectively, e.g. depending on the group membership of the remote access user. strongSwan makes this possible by applying wildcard filtering on the VPN user's -distinguished name (ID_DER_ASN1_DN). +distinguished name (_ID_DER_ASN1_DN_). Let's make a practical example: -An organization has a sales department (OU=Sales) and a research group -(OU=Research). In the company intranet there are separate subnets for Sales -(10.0.0.0/24) and Research (10.0.1.0/24) but both groups share a common web -server (10.0.2.100). The VPN clients use Virtual IP addresses that are either +An organization has a sales department (_OU=Sales_) and a research group +(_OU=Research_). In the company intranet there are separate subnets for Sales +(`10.0.0.0/24`) and Research (`10.0.1.0/24`) but both groups share a common web +server (`10.0.2.100`). The VPN clients use Virtual IP addresses that are either assigned statically or from a dynamic pool. The sales and research departments -use IP addresses from separate address pools (10.1.0.0/24) and (10.1.1.0/24), -respectively. An X.509 certificate is issued to each employee, containing in -its subject distinguished name the country (C=CH), the company (O=ACME), -the group membership(OU=Sales or OU=Research) and the common name (e.g. -CN=Bart Simpson). +use IP addresses from separate address pools (`10.1.0.0/24`) and +(`10.1.1.0/24`), respectively. An X.509 certificate is issued to each employee, +containing in its subject distinguished name the country (_C=CH_), the company +(_O=ACME_), the group membership (_OU=Sales_ or _OU=Research_) and the common +name (e.g. _CN=Bart Simpson_). The IPsec policy defined above can now be enforced with the following three IPsec security associations: -conn sales - right=%any - rightid="C=CH, O=ACME, OU=Sales, CN=*" - rightsubnet=10.1.0.0/24 # Sales IP range - leftsubnet=10.0.0.0/24 # Sales subnet - -conn research - right=%any - rightid="C=CH, O=ACME, OU=Research, CN=*" - rightsubnet=10.1.1.0/24 # Research IP range - leftsubnet=10.0.1.0/24 # Research subnet - -conn web - right=%any - rightid="C=CH, O=ACME, OU=*, CN=*" - rightsubnet=10.1.0.0/23 # Remote access IP range - leftsubnet=10.0.2.100/32 # Web server - rightprotoport=tcp # TCP protocol only - leftprotoport=tcp/http # TCP port 80 only - -The '*' character is used as a wildcard in relative distinguished names (RDNs). -In order to match a wildcard template, the ID_DER_ASN1_DN of a peer must contain -the same number of RDNs (selected from the list in section 4.3) appearing in the -exact order defined by the template. + conn sales + right=%any + rightid="C=CH, O=ACME, OU=Sales, CN=*" + rightsourceip=10.1.0.0/24 # Sales IP range + leftsubnet=10.0.0.0/24 # Sales subnet + + conn research + right=%any + rightid="C=CH, O=ACME, OU=Research, CN=*" + rightsourceip=10.1.1.0/24 # Research IP range + leftsubnet=10.0.1.0/24 # Research subnet + + conn web + right=%any + rightid="C=CH, O=ACME, OU=*, CN=*" + rightsubnet=10.1.0.0/23 # Remote access IP range + leftsubnet=10.0.2.100/32 # Web server + rightprotoport=tcp # TCP protocol only + leftprotoport=tcp/http # TCP port 80 only + +The `*` character is used as a wildcard in relative distinguished names (RDNs). +In order to match a wildcard template, the _ID_DER_ASN1_DN_ of a peer must +contain the same number of RDNs (selected from the list given earlier) appearing +in the exact order defined by the template. "C=CH, O=ACME, OU=Research, OU=Special Effects, CN=Bart Simpson" matches the templates "C=CH, O=ACME, OU=Research, OU=*, CN=*" - "C=CH, O=ACME, OU=*, OU=Special Effects, CN=*" - "C=CH, O=ACME, OU=*, OU=*, CN=*" but not the template @@ -879,79 +778,74 @@ but not the template which doesn't have the same number of RDNs. -4.7 IPsec policies based on CA certificates - --------------------------------------- - -As an alternative to the wildcard based IPsec policies described in section 4.6, -access to specific client host and subnets can be controlled on the basis of -the CA that issued the peer certificate +### IPsec policies based on CA certificates ### +As an alternative to the wildcard based IPsec policies described above, access +to specific client host and subnets can be controlled on the basis of the CA +that issued the peer certificate -conn sales - right=%any - rightca="C=CH, O=ACME, OU=Sales, CN=Sales CA" - rightsubnet=10.1.0.0/24 # Sales IP range - leftsubnet=10.0.0.0/24 # Sales subnet + conn sales + right=%any + rightca="C=CH, O=ACME, OU=Sales, CN=Sales CA" + rightsourceip=10.1.0.0/24 # Sales IP range + leftsubnet=10.0.0.0/24 # Sales subnet -conn research - right=%any - rightca="C=CH, O=ACME, OU=Research, CN=Research CA" - rightsubnet=10.1.1.0/24 # Research IP range - leftsubnet=10.0.1.0/24 # Research subnet + conn research + right=%any + rightca="C=CH, O=ACME, OU=Research, CN=Research CA" + rightsourceip=10.1.1.0/24 # Research IP range + leftsubnet=10.0.1.0/24 # Research subnet -conn web - right=%any - rightca="C=CH, O=ACME, CN=ACME Root CA" - rightsubnet=10.1.0.0/23 # Remote access IP range - leftsubnet=10.0.2.100/32 # Web server - rightprotoport=tcp # TCP protocol only - leftprotoport=tcp/http # TCP port 80 only + conn web + right=%any + rightca="C=CH, O=ACME, CN=ACME Root CA" + rightsubnet=10.1.0.0/23 # Remote access IP range + leftsubnet=10.0.2.100/32 # Web server + rightprotoport=tcp # TCP protocol only + leftprotoport=tcp/http # TCP port 80 only -In the example above, the connection "sales" can be used by peers +In the example above, the connection _sales_ can be used by peers presenting certificates issued by the Sales CA, only. In the same way, -the use of the connection "research" is restricted to owners of certificates -issued by the Research CA. The connection "web" is open to both "Sales" and -"Research" peers because the required "ACME Root CA" is the issuer of the -Research and Sales intermediate CAs. If no rightca parameter is present +the use of the connection _research_ is restricted to owners of certificates +issued by the Research CA. The connection _web_ is open to both "Sales" and +"Research" peers because the required _ACME Root CA_ is the issuer of the +Research and Sales intermediate CAs. If no `rightca` parameter is present then any valid certificate issued by one of the trusted CAs in -/etc/ipsec.d/cacerts can be used by the peer. +`/etc/ipsec.d/cacerts` can be used by the peer. -The leftca parameter usually doesn't have to be set explicitly because +The `leftca` parameter usually doesn't have to be set explicitly because by default it is set to the issuer field of the certificate loaded via -leftcert. The statement +`leftcert`. The statement rightca=%same sets the CA requested from the peer to the CA used by the left side itself as e.g. in -conn sales - right=%any - rightca=%same - leftcert=mySalesCert.pem + conn sales + right=%any + rightca=%same + leftcert=mySalesCert.pem -5. Configuring certificates and CRLs - --------------------------------- +## Configuring certificates and CRLs ## -5.1 Installing the CA certificates - ------------------------------ +### Installing the CA certificates ### X.509 certificates received by strongSwan during the IKE protocol are automatically authenticated by going up the trust chain until a self-signed root CA certificate is reached. Usually host certificates are directly signed by a root CA, but strongSwan also supports multi-level hierarchies with intermediate CAs in between. All CA certificates belonging to a trust chain -must be copied in either binary DER or base64 PEM format into the directory +must be copied in either binary DER or Base64 PEM format into the directory /etc/ipsec.d/cacerts/ -5.2 Installing optional certificate revocation lists (CRLs) - ------------------------------------------------------- +### Installing optional certificate revocation lists (CRLs) ### -By copying a CA certificate into /etc/ipsec.d/cacerts/, automatically all user +By copying a CA certificate into `/etc/ipsec.d/cacerts/`, automatically all user or host certificates issued by this CA are declared valid. Unfortunately, private keys might get compromised inadvertently or intentionally, personal certificates of users leaving a company have to be blocked immediately, etc. @@ -960,97 +854,85 @@ contain the serial numbers of all user or host certificates that have been revoked due to various reasons. After successful verification of the X.509 trust chain, strongSwan searches its -list of CRLs either obtained by loading them from the /etc/ipsec.d/crls/ -directory or fetching them dynamically from a HTTP or LDAP server for the +list of CRLs, either obtained by loading them from the `/etc/ipsec.d/crls/` +directory, or fetching them dynamically from a HTTP or LDAP server, for the presence of a CRL issued by the CA that has signed the certificate. If the serial number of the certificate is found in the CRL then the public key -contained in the certificate is declared invalid and the IPsec SA will not be -established. If no CRL is found or if the deadline defined in the nextUpdate +contained in the certificate is declared invalid and the IKE SA will not be +established. If no CRL is found or if the deadline defined in the _nextUpdate_ field of the CRL has been reached, a warning is issued but the public key will -nevertheless be accepted. CRLs must be stored either in binary DER or base64 -PEM format in the crls directory. +nevertheless be accepted (this behavior can be changed, see below). CRLs must +be stored either in binary DER or Base64 PEM format in the `crls` directory. -5.3 Dynamic update of certificates and CRLs - --------------------------------------- +### Dynamic update of certificates and CRLs ### strongSwan reads certificates and CRLs from their respective files during system startup and keeps them in memory. X.509 certificates have a finite life span defined by their validity field. Therefore it must be possible to replace CA or OCSP certificates kept in system memory without disturbing established IKE SAs. Certificate revocation lists should also be updated in the regular intervals -indicated by the nextUpdate field in the CRL body. The following interactive +indicated by the _nextUpdate_ field in the CRL body. The following interactive commands allow the manual replacement of the various files: -+---------------------------------------------------------------------------+ -| ipsec rereadsecrets reload file /etc/ipsec.secrets | -|---------------------------------------------------------------------------| -| ipsec rereadcacerts reload all files in /etc/ipsec.d/cacerts/ | -|---------------------------------------------------------------------------| -| ipsec rereadaacerts reload all files in /etc/ipsec.d/aacerts/ | -|---------------------------------------------------------------------------| -| ipsec rereadocspcerts reload all files in /etc/ipsec.d/ocspcerts/ | -|---------------------------------------------------------------------------| -| ipsec rereadacerts reload all files in /etc/ipsec.d/acerts/ | -|---------------------------------------------------------------------------| -| ipsec rereadcrls reload all files in /etc/ipsec.d/crls/ | -|---------------------------------------------------------------------------| -| ipsec rereadall ipsec rereadsecrets | -| rereadcacerts | -| rereadaacerts | -| rereadocspcerts | -| rereadacerts | -| rereadcrls | -|---------------------------------------------------------------------------| -| ipsec purgeocsp purge the OCSP cache and fetching requests | -+---------------------------------------------------------------------------+ + +| Command | Action | +|-------------------------|-------------------------------------------------| +| ipsec rereadaacerts | reload all files in `/etc/ipsec.d/aacerts/` | +| ipsec rereadacerts | reload all files in `/etc/ipsec.d/acerts/` | +| ipsec rereadcacerts | reload all files in `/etc/ipsec.d/cacerts/` | +| ipsec rereadcrls | reload all files in `/etc/ipsec.d/crls/` | +| ipsec rereadocspcerts | reload all files in `/etc/ipsec.d/ocspcerts/` | +| ipsec rereadsecrets | reload `/etc/ipsec.secrets` and configured keys | +| ipsec rereadall | all the commands above combined | +| ipsec purgecerts | purge all cached certificates | +| ipsec purgecrl | purge all cached CRLs | +| ipsec purgeocsp | purge the OCSP cache | + CRLs can also be automatically fetched from an HTTP or LDAP server by using the CRL distribution points contained in X.509 certificates. -5.4 Local caching of CRLs - --------------------- +### Local caching of CRLs ### -The the ipsec.conf option +The `ipsec.conf` option - config setup - cachecrls=yes + config setup + cachecrls=yes activates the local caching of CRLs that were dynamically fetched from an -HTTP or LDAP server. Cached copies are stored in /etc/ipsec.d/crls using a -unique filename formed from the issuer's SubjectKeyIdentifier and the -suffix .crl. +HTTP or LDAP server. Cached copies are stored in `/etc/ipsec.d/crls` using a +unique filename formed from the issuer's _subjectKeyIdentifier_ and the +suffix `.crl`. With the cached copy the CRL is immediately available after startup. When the local copy is about to expire it is automatically replaced with an updated CRL fetched from one of the defined CRL distribution points. -5.5 Online Certificate Status Protocol (OCSP) - ----------------------------------------- +### Online Certificate Status Protocol (OCSP) ### -The Online Certificate Status Protocol is defined by RFC 2560. It can be +The _Online Certificate Status Protocol_ is defined by RFC 2560. It can be used to query an OCSP server about the current status of an X.509 certificate and is often used as a more dynamic alternative to a static Certificate Revocation List (CRL). Both the OCSP request sent by the client and the OCSP response messages returned by the server are transported via a standard -TCP/HTTP connection. Therefore cURL support must be enabled during -configuration. +TCP/HTTP connection. In the simplest OCSP setup, a default URI under which the OCSP server for a -given CA can be accessed is defined in ipsec.conf: +given CA can be accessed is defined in `ipsec.conf`: - ca strongswan - cacert=strongswanCert.pem - ocspuri=http://ocsp.strongswan.org:8880 - auto=add + ca strongswan + cacert=strongswanCert.pem + ocspuri=http://ocsp.strongswan.org:8880 + auto=add The HTTP port can be freely chosen. OpenSSL implements an OCSP server that can be used in conjunction with an -openssl-based Public Key Infrastructure. The OCSP server is started with the +OpenSSL-based Public Key Infrastructure. The OCSP server is started with the following command: openssl ocsp -index index.txt -CA strongswanCert.pem -port 8880 \ @@ -1059,34 +941,35 @@ following command: The command consists of the parameters - -index index.txt is a copy of the OpenSSL index file containing the list of - all issued certificates. The certificate status in index.txt - is designated either by V for valid or R for revoked. If a new - certificate is added or if a certificate is revoked using the - openssl ca command, the OCSP server must be restarted in order for - the changes in index.txt to take effect. + -index index.txt is a copy of the OpenSSL index file containing the list + of all issued certificates. The certificate status in index.txt + is designated either by V for valid or R for revoked. If a new + certificate is added or if a certificate is revoked using the + openssl ca command, the OCSP server must be restarted in order for + the changes in index.txt to take effect. - -CA the CA certificate + -CA the CA certificate - -port the HTTP port the OCSP server is listening on. + -port the HTTP port the OCSP server is listening on. - -rkey the private key used to sign the OCSP response. The use of the - sensitive CA private key is not recommended since this could - jeopardize the security of your production PKI if the OCSP - server is hacked. It is much better to generate a special - RSA private key just for OCSP signing use instead. + -rkey the private key used to sign the OCSP response. The use of the + sensitive CA private key is not recommended since this could + jeopardize the security of your production PKI if the OCSP + server is hacked. It is much better to generate a special + RSA private key just for OCSP signing use instead. - -rsigner the certificate of the OCSP server containing a public key which - matches the private key defined by -rkey and which can be used by - the client to check the trustworthiness of the signed OCSP response. + -rsigner the certificate of the OCSP server containing a public key which + matches the private key defined by -rkey and which can be used by + the client to check the trustworthiness of the signed OCSP + response. - -resp_no_certs With this option the OCSP signer certificate defined by - -rsigner is not included in the OCSP response. + -resp_no_certs With this option the OCSP signer certificate defined by + -rsigner is not included in the OCSP response. - -nmin the validity interval of an OCSP response given in minutes. + -nmin the validity interval of an OCSP response given in minutes. - -text this option activates a verbose logging output, showing the contents - of both the received OCSP request and sent OCSP response. + -text this option activates a verbose logging output, showing the + contents of both the received OCSP request and sent OCSP response. The OCSP signer certificate can either be put into the default directory @@ -1100,91 +983,90 @@ must be included in the OCSP server certificate. Just insert the parameter extendedKeyUsage=OCSPSigner -in the [ usr_cert ] section of your openssl.cnf configuration file before +in the `[ usr_cert ]` section of your `openssl.cnf` configuration file before the CA signs the OCSP server certificate. -For a given CA the corresponding ca section in ipsec.conf (see section 7) allows +For a given CA the corresponding _ca_ section in `ipsec.conf` (see below) allows to define the URI of a single OCSP server. As an alternative an OCSP URI can be embedded into each host and user certificate by putting the line authorityInfoAccess = OCSP;URI:http://ocsp.strongswan.org:8880 -into the [ usr_cert ] section of your openssl.cnf configuration file. -If an OCSP authorityInfoAccess extension is present in a certificate then this +into the `[ usr_cert ]` section of your `openssl.cnf` configuration file. +If an OCSP _authorityInfoAccess_ extension is present in a certificate then this record overrides the default URI defined by the ca section. -5.6 CRL Policy - ---------- +### CRL Policy ### By default strongSwan is quite tolerant concerning the handling of CRLs. It is -not mandatory for a CRL to be present in /etc/ipsec.d/crls and if the expiration -date defined by the nextUpdate field of a CRL has been reached just a warning -is issued but a peer certificate will always be accepted if it has not been -revoked. +not mandatory for a CRL to be present in `/etc/ipsec.d/crls` and if the +expiration date defined by the _nextUpdate_ field of a CRL has been reached just +a warning is issued but a peer certificate will always be accepted if it has not +been revoked. If you want to enforce a stricter CRL policy then you can do this by setting -the "strictcrlpolicy" option. This is done in the "config setup" section -of the ipsec.conf file: +the `strictcrlpolicy` option. This is done in the `config setup` section +of the `ipsec.conf` file: config setup strictcrlpolicy=yes ... A certificate received from a peer will not be accepted if no corresponding -CRL or OCSP response is available. And if an ISAKMP SA re-negotiation takes -place after the nextUpdate deadline has been reached, the peer certificate -will be declared invalid and the cached RSA public key will be deleted, causing +CRL or OCSP response is available. And if an IKE SA re-negotiation takes +place after the _nextUpdate_ deadline has been reached, the peer certificate +will be declared invalid and the cached public key will be deleted, causing the connection in question to fail. Therefore if you are going to use the -"strictcrlpolicy=yes" option, make sure that the CRLs will always be updated -in time. Otherwise a total standstill would ensue. +`strictcrlpolicy=yes` option, make sure that the CRLs will always be updated +in time. Otherwise a total standstill might ensue. -As mentioned earlier the default setting is "strictcrlpolicy=no" +As mentioned earlier the default setting is `strictcrlpolicy=no`. -5.7 Configuring the peer side using locally stored certificates - ----------------------------------------------------------- +### Configuring the peer side using locally stored certificates ### -If you don't want to use trust chains based on CA certificates as proposed in -section 4.3 you can alternatively import trusted peer certificates directly. -Thus you do not have to rely on the certificate to be transmitted by the peer -as part of the IKE protocol. +If you don't want to use trust chains based on CA certificates as proposed above +you can alternatively import trusted peer certificates directly. -With the conn %default section defined in section 4.1 and the use of the -rightcert keyword for the peer side, the connection definitions in section 4.3 -can alternatively be written as +With the `conn %default` section defined above and the use of the `rightcert` +keyword for the peer side, the connection definitions presented earlier can +alternatively be written as conn sun right=%any - rightid=@sun.strongswan.org + rightid=sun.strongswan.org rightcert=sunCert.cer conn carol right=192.168.0.100 rightcert=carolCert.der -If the peer certificates are loaded locally then there is no sense in sending -any certificates to the other end via the IKE protocol. Especially if -self-signed certificates are used which wouldn't be accepted anyway by -the other side. In these cases it is recommended to add +If the peer certificates are loaded locally then there is no need to send any +certificates to the other end via the IKE protocol. Especially if self-signed +certificates are used which wouldn't be accepted anyway by the other side. +In these cases it is recommended to add leftsendcert=never -to the connection definition[s] in order to avoid the sending of the host's +to the connection definition(s) in order to avoid the sending of the host's own certificate. The default value is leftsendcert=ifasked -If a peer does not send a certificate request then use the setting +which causes certificates to only be sent if a certificate request is received. +If a peer does not send a certificate request then the setting leftsendcert=always -If a peer certificate contains a subjectAltName extension, then an alternative -rightid type can be used, as the example "conn sun" shows. If no rightid +may be used to force sending of the certificate to the other peer. + +If a peer certificate contains a _subjectAltName_ extension, then an alternative +`rightid` type can be used, as the example `conn sun` shows. If no `rightid` entry is present then the subject distinguished name contained in the certificate is taken as the ID. -Using the same rules concerning pathnames that apply to strongSwan's own +Using the same rules concerning pathnames that apply to the gateway's own certificates, the following two definitions are also valid for trusted peer certificates: @@ -1195,21 +1077,20 @@ or rightcert=/usr/ssl/certs/carolCert.der -6. Configuring the private keys - ipsec.secrets - -------------------------------------------- +## Configuring the private keys - ipsec.secrets ## + -6.1 Loading private key files in PKCS#1 or PKCS#8 format - ---------------------------------------------------- +### Loading private key files ### -Besides strongSwan's raw private key format strongSwan has been enabled to -load RSA (or ECDSA) private keys in the PKCS#1 or PKCS#8 file format. -The key files can be optionally secured with a passphrase. +strongSwan is able to load RSA (or ECDSA) private keys in the PKCS#1 or PKCS#8 +file formats, or from PKCS#12 containers. The key files can optionally be +secured with a passphrase. -RSA private key files are declared in /etc/ipsec.secrets using the syntax +RSA private key files are declared in `/etc/ipsec.secrets` using the syntax : RSA <my keyfile> "<optional passphrase>" -The key file can be either in base64 PEM-format or binary DER-format. The +The key file can be either in Base64 PEM-format or binary DER-format. The actual coding is detected automatically. The example : RSA moonKey.pem @@ -1231,44 +1112,37 @@ cipher using a transport key derived from a cryptographically strong passphrase. Once on the security gateway the private key can either be permanently -unlocked so that it can be used by Pluto without having to know a +unlocked so that it can be used by the IKE daemon without having to know a passphrase openssl rsa -in moonKey.pem -out moonKey.pem or as an option the key file can remain secured. In this case the passphrase unlocking the private key must be added after the pathname in -/etc/ipsec.secrets +`/etc/ipsec.secrets` : RSA moonKey.pem "This is my passphrase" -Some CAs distribute private keys embedded in a PKCS#12 file. Since strongSwan -is not yet able to read this format directly, the private key part must -first be extracted using the command - - openssl pkcs12 -nocerts -in moonCert.p12 -out moonKey.pem - -if the key file moonKey.pem is to be secured again by a passphrase, or - - openssl pkcs12 -nocerts -nodes -in moonCert.p12 -out moonKey.pem +Some CAs distribute private keys embedded in a PKCS#12 file. strongSwan can read +private keys directly from such a file (end-entity and CA certificates are +also extracted): -if the private key is to be stored unlocked. + : P12 moonCert.p12 "This is my passphrase" -6.2 Entering passphrases interactively - ---------------------------------- +### Entering passphrases interactively ### On a VPN gateway you would want to put the passphrase protecting the private -key file right into /etc/ipsec.secrets as described in the previous paragraph, +key file right into `/etc/ipsec.secrets` as described in the previous section, so that the gateway can be booted in unattended mode. The risk of keeping unencrypted secrets on a server can be minimized by putting the box into a locked room. As long as no one can get root access on the machine the private keys are safe. On a mobile laptop computer the situation is quite different. The computer can -be stolen or the user is leaving it unattended so that unauthorized persons +be stolen or the user may leave it unattended so that unauthorized persons can get access to it. In theses cases it would be preferable not to keep any -passphrases openly in /etc/ipsec.secrets but to prompt for them interactively +passphrases openly in `/etc/ipsec.secrets` but to prompt for them interactively instead. This is easily done by defining : RSA moonKey.pem %prompt @@ -1287,228 +1161,138 @@ and which causes a passphrase prompt to appear. To abort entering a passphrase enter just a carriage return. -6.3 Multiple private keys - --------------------- +## Configuring CA properties - ipsec.conf ## -strongSwan supports multiple private keys. Since the connections defined -in ipsec.conf can find the correct private key based on the public key -contained in the certificate assigned by leftcert, default private key -definitions without specific IDs can be used - - : RSA myKey1.pem "<optional passphrase1>" - - : RSA myKey2.pem "<optional passphrase2>" - - -7. Configuring CA properties - ipsec.conf - -------------------------------------- - -Besides the definition of IPsec connections the ipsec.conf file can also +Besides the definition of IPsec connections the `ipsec.conf` file can also be used to configure a few properties of the certification authorities needed to establish the X.509 trust chains. The following example shows some of the parameters that are currently available: ca strongswan - cacert=strongswanCert.pem - ocspuri=http://ocsp.strongswan.org:8880 - crluri=http://crl.strongswan.org/strongswan.crl' - crluri2="ldap://ldap.strongswan.org/O=strongSwan, C=CH?certificateRevocationList" - auto=add + cacert=strongswanCert.pem + ocspuri=http://ocsp.strongswan.org:8880 + crluri=http://crl.strongswan.org/strongswan.crl' + crluri2="ldap://ldap.strongswan.org/O=strongSwan, C=CH?certificateRevocationList" + auto=add -In a similar way as conn sections are used for connection definitions, an -arbitrary number of optional ca sections define the basic properties of CAs. +In a similar way as `conn` sections are used for connection definitions, an +arbitrary number of optional `ca` sections define the basic properties of CAs. Each ca section is named with a unique label - ca strongswan + ca strongswan The only mandatory parameter is - cacert=strongswanCert.pem + cacert=strongswanCert.pem which points to the CA certificate which usually resides in the default -directory /etc/ipsec.d/cacerts/ but could also be retrieved via an absolute +directory `/etc/ipsec.d/cacerts/` but could also be retrieved via an absolute path name. The OCSP URI - ocspuri=http://ocsp.strongswan.org:8880 + ocspuri=http://ocsp.strongswan.org:8880 allows to define an individual OCSP server per CA. Also up to two additional CRL distribution points (CDPs) can be defined - crluri=http://crl.strongswan.org/strongswan.crl' - crluri2="ldap://ldap.strongswan.org/O=strongSwan, C=CH?certificateRevocationList" + crluri=http://crl.strongswan.org/strongswan.crl' + crluri2="ldap://ldap.strongswan.org/O=strongSwan, C=CH?certificateRevocationList" which are added to any CDPs already present in the received certificates themselves. -With the auto=add statement the ca definition is automatically loaded during -startup. Setting auto=ignore will ignore the ca section. +With the `auto=add` statement the `ca` definition is automatically loaded during +startup. Setting `auto=ignore` will ignore the `ca` section. Any parameters which appear in several ca definitions can be put in -a common ca %default section +a common `ca %default` section ca %default - crluri=http://crl.strongswan.org/strongswan.crl' + crluri=http://crl.strongswan.org/strongswan.crl' -8. Monitoring functions - -------------------- +## Monitoring functions ## strongSwan offers the following monitoring functions: -The command - - ipsec listalgs +| Command | Action | +|---------------------|---------------------------------------------------| +| ipsec listaacerts | list all Authorization Authority certificates loaded from `/etc/ipsec.d/aacerts/` | +| ipsec listacerts | list all X.509 attribute certificates loaded from `/etc/ipsec.d/acerts/` | +| ipsec listalgs | list cryptographic algorithms for IKE | +| ipsec listcacerts | list all CA certificates loaded from `/etc/ipsec.d/cacerts/` or received via IKE | +| ipsec listcainfos | list all properties defined in `ca` sections in `ipsec.conf` | +| ipsec listcerts | list all certificates loaded via `leftcert` and `rightcert` | +| ipsec listcounters | list global or connection specific counter values | +| ipsec listcrls | list all CLRs loaded from `/etc/ipsec.d/crls/` | +| ipsec listocsp | list contents of the OCSP response cache | +| ipsec listocspcerts | list all OCSP signer certificates loaded from `/etc/ipsec.d/ocspcerts/` or received in OCSP responses | +| ipsec listplugins | list all loaded plugin features | +| ipsec listpubkeys | list all raw public keys e.g. loaded via `leftsigkey` and `rightsigkey` | +| ipsec listall | all the above commands combined | +| ipsec status | list concise status information on established connections | +| ipsec statusall | list detailed status information on connections | -lists all IKE cryptographic algorithms that are currently -registered with strongSwan. +## Firewall support functions ## -The command - ipsec listcerts [--utc] - -lists all local certificates, both strongSwan's own and those of -trusted peer loaded via leftcert and rightcert, respectively. - - -The command - - ipsec listcacerts [--utc] - -lists all CA certificates that have been either been loaded from the directory -/etc/ipsec.d/cacerts/ or received via the IKE protocol. - - -The command - - ipsec listaacerts [--utc] - -lists all Authorization Authority certificates that have been loaded from -the directory /etc/ipsec.d/aacerts/. - - -The command - - ipsec listocspcerts [--utc] - -lists all OCSO signer certificates that have been either loaded from -/etc/ipsec.d/ocspcerts/ or have been received included in the OCSP server -response. - - -The command - - ipsec listacerts [--utc] - -lists all X.509 attribute certificates that have been loaded from the directory -/etc/ipsec.d/acerts/. - - -The command - - ipsec listcainfos [--utc] - -lists the properties defined by the ca definition sections in ipsec.conf. - - -The command - - ipsec listcrls [--utc] - -lists all CRLs that have been loaded from /etc/ipsec.d/crls/. - - -The command - - - ipsec listocsp [--utc] - -lists the contents of the OCSP response cache. - - -The command - - ipsec listall [--utc] - -is equivalent to using all of the above commands. - - -9. Firewall support functions - -------------------------- - - -9.1 Environment variables in the updown script - ------------------------------------------ +### Environment variables in the updown script ### strongSwan makes the following environment variables available -in the updown script indicated by the leftupdown option: - -+-------------------------------------------------------------------+ -| Variable Example Comment | -|-------------------------------------------------------------------| -| $PLUTO_PEER_ID carol@strongswan.org RFC822_ADDR (1) | -|-------------------------------------------------------------------| -| $PLUTO_PEER_PROTOCOL 17 udp (2) | -|-------------------------------------------------------------------| -| $PLUTO_PEER_PORT 68 bootpc (3) | -|-------------------------------------------------------------------| -| $PLUTO_PEER_CA C=CH, O=ACME, CN=Sales CA (4) | -|-------------------------------------------------------------------| -| $PLUTO_MY_ID @moon.strongswan.org FQDN (1) | -|-------------------------------------------------------------------| -| $PLUTO_MY_PROTOCOL 17 udp (2) | -|-------------------------------------------------------------------| -| $PLUTO_MY_PORT 67 bootps (3) | -+-------------------------------------------------------------------+ +in the _updown_ script indicated by the `leftupdown` option: + +| Variable | Example | Comment | +|-----------------------|---------------------------|-----------------| +| $PLUTO_PEER_ID | carol@strongswan.org | RFC822_ADDR (1) | +| $PLUTO_PEER_PROTOCOL | 17 | udp (2) | +| $PLUTO_PEER_PORT | 68 | bootpc (3) | +| $PLUTO_MY_ID | moon.strongswan.org | FQDN (1) | +| $PLUTO_MY_PROTOCOL | 17 | udp (2) | +| $PLUTO_MY_PORT | 67 | bootps (3) | (1) $PLUTO_PEER_ID/$PLUTO_MY_ID contain the IDs of the two ends of an established connection. In our examples these - correspond to the strings defined by rightid and leftid, + correspond to the strings defined by `rightid` and `leftid`, respectively. (2) $PLUTO_PEER_PROTOCOL/$PLUTO_MY_PROTOCOL contain the protocol - defined by the rightprotoport and leftprotoport options, + defined by the `rightprotoport` and `leftprotoport` options, respectively. Both variables contain the same protocol value. The variables take on the value '0' if no protocol has been defined. (3) $PLUTO_PEER_PORT/$PLUTO_MY_PORT contain the ports defined by - the rightprotoport and leftprotoport options, respectively. + the `rightprotoport` and `leftprotoport` options, respectively. The variables take on the value '0' if no port has been defined. -(4) $PLUTO_PEER_CA contains the distinguished name of the CA that - issued the peer's certificate. - There are several more, refer to the provided default script for a documentation -of these. +of them. -9.2 Automatic insertion and deletion of iptables firewall rules - ----------------------------------------------------------- +### Automatic insertion and deletion of iptables firewall rules ### -The default _updown script automatically inserts and deletes dynamic iptables -firewall rules upon the establishment or teardown, respectively, of an IPsec -security association. This feature is activated with the line +The default `_updown` script automatically inserts and deletes dynamic +`iptables` firewall rules upon the establishment or teardown, respectively, of +an IPsec security association. This feature is activated with the line - leftfirewall=yes + leftfirewall=yes -If you define a local client subnet with a netmask larger than /32 behind -the gateway then the automatically inserted FORWARD iptables rules will -not allow to access the internal IP address of the host although it is -part of the client subnet definition. If you want additional INPUT and -OUTPUT iptables rules to be inserted, so that the host itself can be accessed -then add the following line: +If you define a `leftsubnet` with a netmask larger than `/32` then the +automatically inserted _FORWARD_ `iptables` rules will not allow clients to +access the internal IP address of the gateway even if it is part of that subnet +definition. If you want additional _INPUT_ and _OUTPUT_ `iptables` rules to be +inserted, so that the host itself can be accessed then add the following line: - lefthostaccess=yes + lefthostaccess=yes -The _updown script also features a logging facility which will register the +The `_updown` script also features a logging facility which will register the creation (+) and the expiration (-) of each successfully established VPN connection in a special syslog file in the following concise and easily readable format: -Jul 19 18:58:38 moon vpn: - + @carol.strongswan.org 192.168.0.100 -- 192.168.0.1 == 10.1.0.0/16 -Jul 19 22:15:17 moon vpn: - - @carol.strongswan.org 192.168.0.100 -- 192.168.0.1 == 10.1.0.0/16 + Jul 19 18:58:38 moon vpn: + + carol.strongswan.org 192.168.0.100 -- 192.168.0.1 == 10.1.0.0/16 + Jul 19 22:15:17 moon vpn: + - carol.strongswan.org 192.168.0.100 -- 192.168.0.1 == 10.1.0.0/16 |