strongSwan Client Support

Remote Access client with IKEv2 has the ability to use the strongSwan Client.

strongSwan Client Installation

For strongSwan client installation, follow the instructions in the strongSwan documentation.

strongSwan Client Configuration

The configuration contains these sections:

Section Description

Certificate

This section describes:

  • The "ipsec.conf" file

  • The "ipsec.secrets" file

  • The "strongswan.conf" file

  • The "cacerts" folder

  • The "certs" folder

  • The "private" folder

Username and Password

This section describes:

  • The "ipsec.conf" file

  • The "ipsec.secrets" file

  • The "strongswan.conf" file

Features Configuration

This section describes:

  • The "pfs" feature

  • The "reauth" feature

  • The "rekey" feature

  • The strict use of IKE and ESP methods

  • Dead Peer Detection (DPD)

Special Configuration

This section describes:

  • How to use an encrypted private key to connect

  • The encryption domain

  1. File:

    /etc/strongswan/ipsec.conf

    Description:

    In this file, you configure how the strongSwan client communicates with Check Point Security GatewayClosed Dedicated Check Point server that runs Check Point software to inspect traffic and enforce Security Policies for connected network resources. through certificate authentication.

    The contact of the file:

    • config setup

      • charondebug="ike 4, knl 4, cfg 3, chd 4"

    • conn CONNECTION_NAME

      • type=tunnel

        By default, this is a tunnel.

      • leftfirewall=yes

      • authby=pubkey

      • keyexchange=ikev2

      • left=<CLIENT_EXTERNAL_IP_ADDRESS>

        By default, this is %any.

        The value %any for the local endpoint signifies an address that fills (by automatic keying) during negotiation.

        If the local peer initiates the connection setup, routing table queries determine the correct local IP address.

      • leftsourceip=%config

        Makes the peer ask for virtual IP (Office Mode IP), DNS, and other settings.

      • right=<GW_EXTERNAL_IP_ADDRESS>

      • rightid=<GW_EXTERNAL_IP_ADDRESS>

      • leftcert=<CLIENT_CERTIFICATE_FILE>

        Example: StrongSwanPublicCert.cer

      • rightsubnet=ENCRYPTION_DOMAIN_WE_WANT_TO_CONNECT

        If you want to connect to the entire encryption domain, use 0.0.0.0/0.

      • ike=<IKE_METHODS_AS_CONFIGURED_ON_THE_GW>

        Example: aes256-sha1-modp1024

        You must configure the Security Gateway to support those methods.

      • esp=<IPSEC_METHODS_AS_CONFIGURED_ON_THE_GW>

        Example: 3des-sha1

        You must edit the Gateway to support those methods.

      • ikelifetime=<TIME_WHICH_AFTER_THE_IKE_SA_IS_NOT_VALID>

        Example: 24h

        Absolute time after which an IKE SA expires.

        It can be hours (h), minutes (m), and seconds (s).

      • lifetime=<TIME_WHICH_AFTER_THE_IPSEC_SA_IS_NOT_VALID>

        Example: 1h

        Absolute time after which an IPsec SA expires.

        It can be hours (h), minutes (m), and seconds (s).

      • reauth=yes

      • rekey=yes

      • margintime=<TIME_TO_START_REKEY_OR_REAUTH_BEFORE_EXPIRY>

        Example 1M

        Time before SA expiry the rekeying should start.

        Example: If the time of lifetime is 1h and margintime is 1, then 1m before the 1h ends, Security Gateway starts the rekey process.

        It can be hours (h), minutes (m), and seconds (s).

      • rekeyfuzz=<RANDOM_TIME_PERCENTAGE_FOR_REKEY_AND_REAUTH>

        Example: 50%

        The percentage by which margintime randomly increases (may exceed 100%).

        You can disable randomization with rekeyfuzz=0%.

        This is the formula of the rekytime of IPsec SAs and IKE SA:

        rekeytime = lifetime - (margintime + random(0, margintime * rekeyfuzz))

      • auto=add

      • dpdaction=restart

        Restart immediately triggers an attempt to re-negotiate the connection after no response from the Gateway.

      • dpddelay=<TIME_TO_SEND_R_U_THERE_MESSAGE>

        Example: 30s

        Defines the period time interval with which R_U_THERE messages and INFORMATIONAL exchanges go to the peer.

        These only go if no other traffic is received.

        It can be hours (h), minutes (m), and seconds (s).

      • dpdtimeout=<TIMEOUT_INTERVAL_TO_DELETE_THE_CONNECTION>

        Example: 60s

        Defines the timeout interval, after which all connections to a peer delete in case of inactivity.

        It can be hours (h), minutes (m), and seconds (s).

    Advanced configuration and explanation:

    See the strongSwan documentation in the section for General Connection Parameters.

  2. File:

    /etc/strongswan/ipsec.secrets

    Description:

    It this file, you configure the strongSwan private key.

    The contact of the file:

    THE_SITE_IP_ADDRESS (OPTIONAL) : RSA CLIENT_CERT_KEY_FILE

    Example: StrongSwanPrivateKey.pem

  3. File:

    /etc/strongswan/strongswan.conf

    Description:

    The strongSwan Configuration file adds more plugins, sends the vendor ID, and resolves the DNS.

    The contact of the file:

    charon {
  load_modular = yes
  send_vendor_id = yes
  plugins {
    include strongswan.d/charon
    resolve {
      file = /etc/resolv.conf
    }
  }
}
include strongswan.d/*.conf

    Advanced configuration and explanation:

    See the strongSwan documentation in the section for the strongswan.conf file.

  4. Directory Path:

    /etc/strongswan/ipsec.d/certs

    File:

    StrongSwanPublicCert.cer

    or

    StrongSwanPublicCert.pem

    Description:

    This folder contains all the client public certificates.

  5. Directory Path:

    /etc/strongswan/ipsec.d/private

    File:

    StrongSwanPrivateKey.pem

    Description:

    This folder contains all the client private certificates.

  1. File:

    /etc/strongswan/ipsec.conf

    Description:

    In this file, you configure how the strongSwan client communicates with Check Point Security Gateway through username and password authentication.

    The contact of the file:

    • config setup

      • charondebug="ike 4, knl 4, cfg 3, chd 4"

    • conn CONNECTION_NAME

      • type=tunnel

        This is the default.

      • leftfirewall=yes

      • rightauth=pubkey

      • leftauth=eap-gtc

      • keyexchange=ikev2

      • eap_identity=<USERNAME>

      • left=<CLIENT_EXTERNAL_IP_ADDRESS>

        This configuration is not a necessity.

        By default, it is %any. The value %any for the local endpoint signifies an address that fills in (by automatic keying) during negotiation.

        If the local peer initiates the connection setup, routing table queries determine the correct local IP address.

      • leftsourceip=%config

        Makes the peer ask for the virtual IP (Office Mode IP), DNS, and other settings.

      • right=<GW_EXTERNAL_IP_ADDRESS>

      • rightid=<GW_EXTERNAL_IP_ADDRESS>

      • rightsubnet=<ENCRYPTION_DOMAIN_WE_WANT_TO_CONNECT>

        If you want to connect to the entire encryption domain, use 0.0.0.0/0.

      • ike=<IKE_METHODS_AS_CONFIGURED_ON_THE_GW>

        Example: aes256-sha1-modp1024

        You must configure the Security Gateway to support those methods.

      • esp=<IPSEC_METHODS_AS_CONFIGURED_ON_THE_GW>

        Example: 3des-sha1

        You must configure the Security Gateway to support those methods.

      • ikelifetime=<TIME_WHICH_AFTER_THE_IKE_SA_IS_NOT_VALID>

        Example: 24h

        Absolute time after which an IKE SA expires.

        It can be hours (h), minutes (m), and seconds (s).

      • lifetime=<TIME_WHICH_AFTER_THE_IPSEC_SA_IS_NOT_VALID>

        Example: 1h

        Absolute time after which an IPsec SA expires.

        It can be hours (h), minutes (m), and seconds (s).

      • reauth=yes

      • rekey=yes

      • margintime=<TIME_TO_START_REKEY_OR_REAUTH_BEFORE>

        Example 1M

        If the time of 'lifetime' is 1h and margintime is 1m, then 1m before the 1h ends, Security Gateway starts the rekey process.

        It can be hours (h), minutes (m), and seconds (s).

      • rekeyfuzz=<RANDOM_TIME_PERCENTAGE_FOR_REKEY_AND_REAUTH>

        Example: 50%

        The percentage by which margintime randomly increases. It may exceed 100%.

        You may disable randomization with rekeyfuzz=0%.

        This is the formula of the rekytime of IPsec SAs and IKE SA:

        rekeytime = lifetime - (margintime + random(0, margintime * rekeyfuzz))

      • auto=add

      • dpdaction=restart

        A restart immediately triggers an attempt to re-negotiate the connection after no response from the Gateway.

      • dpddelay=<TIME_TO_SEND_R_U_THERE_MESSAGE>

        Example: 30s

        This defines the period time interval with which "R_U_THERE" messages and "INFORMATIONAL" exchanges go to the peer.

        These go if the peer receives no other traffic.

        It can be hours (h), minutes (m), and seconds (s).

      • dpdtimeout=<TIMEOUT_INTERVAL_TO_DELETE_THE_CONNECTION>

        Example: 60s

        This defines the timeout interval, after which all connections to a peer delete in case of inactivity.

        It can be hours (h), minutes (m), and seconds (s).

    Advanced configuration and explanation:

    See the strongSwan documentation in the ipsec.conf: conn section.

  2. File:

    /etc/strongswan/ipsec.secrets

    Description:

    In this file, you configure the strongSwan password.

    The contact of the file:

    USERNAME : EAP "PASSWORD"

    Note - We do not recommend the use of an authentication method that stores a user's clear passwords in the file.

  3. File:

    /etc/strongswan/strongswan.conf

    Description:

    The strongSwan Configuration file adds more plugins, sends the vendor ID, and resolves the DNS.

    The contact of the file:

    charon {
  load_modular = yes
  send_vendor_id = yes
  plugins {
    include strongswan.d/charon
    resolve {
      file = /etc/resolv.conf
    }
  }
}
include strongswan.d/*.conf

    Advanced configuration and explanation:

    See the strongSwan documentation in the strongswan.conf section.

  4. Directory Path:

    /etc/strongswan/ipsec.d/cacerts

    File:

    internal_ca.crt

    Description:

    The internal CA file of all the Gateway, LDAP, and RADIUS servers are the Trusted CA for the client to authenticate the servers for each connection.

    You can find these settings in SmartConsoleClosed Check Point GUI application used to manage a Check Point environment - configure Security Policies, configure devices, monitor products and events, install updates, and so on. under Trusted CA.

  • pfs

    • You must add the "esp=" section with the proper DH group.

    • Example: esp=3des-sha1-modp1024

  • reauth

    • ikelifetime=<TIME_WHICH_AFTER_THE_IKE_SA_IS_NOT_VALID> , reauth=yes

  • rekey

    • lifetime=<TIME_WHICH_AFTER_THE_IPSEC_SA_IS_NOT_VALID> , rekey=yes

  • strict use of IKE and ESP methods

    • You must add the "ike=" or "esp=", or both at the end.

    • Example: ike=aes256-sha1-modp1024! , esp=3des-sha1!

  • Dead Peer Detection

    You must add the "dpdaction=restart" in the "ipsec.conf" file to check the liveliness of the IPsec peer and to keep it alive.

  • How to use an encrypted private key to connect

    • On the ipsec.secrets file, you must add the passphrase for the private key.

    • File:

      /etc/strongswan/ipsec.secrets

      Description:

      In this file, you configure the strongSwan password.

      The contact of the file:

      Example: <THE_SITE_IP_ADDRESS> : <RSA CLIENT_CERT_KEY_FILE> StrongSwanPrivateKey.pem "<PASSPHRASE_FOR_THE_PRIVATE_KEY>" Source

  • Encryption Domain

    • In some scenarios, if you change the encryption domain with an addition or a removal of a network, you must modify the client "ipsec.conf" file.

    • Three ways to configure.

      Note: Two of these require edits on the client side after changes. (Not recommended.)

    • In this setup, three networks are on the encryption domain.

      • Uses the universal IP to connect to the entire Encryption Domain.

        • Configure the "rightsubnet" as a universal IP which is 0.0.0.0/0.

          In this configuration, there are routes to the entire Encryption Domain.

        • If you add or remove any network, it requires no modification on the client side.

          Note - This choice is highly recommended.

      • Specifies one specific network for the connection.

        • Choose one specific network, such as eth0 at 10.10.1.0/24.

          Configure the "rightsubnet" to be "10.10.1.0/24" for one tunnel to this network.

        • Note - If a change in the Encryption Domain now has the network as 10.10.10.0/24, you must change it on the client side.

      • Specifies several networks for the connections.

        • If you do not want to connect to the Encryption Domain or to one network, you can connect to two or more networks.

          Configure these with the "also" macro, which includes connection definitions defined in the ipsec.conf file and add the change to this connection.

        • Example:

          conn conn_to_eth 0

          //full configuration with "rightsubnet=10.10.10.0/24"

          conn coon_to_eth 1

          rightsubnet=192.168.1.0/24

          also=coon_to_eth 0

        • Note:

          • You must still run the up command to establish this connection. If there are any changes in the Encryption Domain that relate to these networks, you must reconfigure the client side.

          • If a network is not accessible to you, the connection fails.

Debian and Ubuntu Special Configuration

To use EAP authentication on Debian and Ubuntu machines, you must run these commands to install the required plugins before a strongSwan restart:

  • sudo apt-get install libstrongswan-extra-plugins

  • sudo apt-get install libcharon-extra-plugins

Useful strongSwan Commands

On CentOS and Fedora, the primary command is: strongswan.

On Ubuntu and Debian, the primary command is: ipsec.

  • strongswan restart, or ipsec restart

    Terminates all IPsec connections, stops the IKE daemon "charon", parses the "ipsec.conf" file, and starts the IKE daemon "charon".

  • strongswan rereadsecrets, or ipsec rereadsecrets

    Reads all secrets defined in the ipsec.secrets file and updates them.

  • strongswan update, or ipsec update

    Determines any changes in the "ipsec.conf" file and updates the configuration on the active IKE daemon "charon".

    Configuration changes do not affect established connections.

    Note - To use changes in the "ipsec.conf" or "ipsec.secrets" file, you must run the command with the "rereadsecrets" options (not with the "update" option). For full command syntax, go to the strongswan.org web site (see the IpsecCommand section).

How to Convert a P12 File into a Private Key and Public Cert

  • XCA Tool

    • Use the XCA tool.

    • Download it from the hohnstaedt.de site in the XCA directory.

  • OpenSSL Commands

    • openssl pkcs12 -in <P12_CERTIFICATE>.p12 -clcerts -nokeys -out <EXTRACTED_CERTIFICATE>.crt

    • openssl pkcs12 -in <P12_CERTIFICATE>.p12 -nocerts -out <EXTRACTED_PRIVATE>.key

Known Limitations

  • Simultaneous Login

    Two simultaneous connections for the same user are not supported. Each connection must be an individual user or the first connection disconnects.

  • Office Mode with Multiple External Interfaces

    Enhancements for Gateways with multiple external interfaces require NAT-T usage on the client side.

    Enforcement requires the NAT-T environment, or the configuration of "forceencaps = yes" in the "ipsec.conf" file.

  • Back Connection

    Connections from the encryption domain to the assigned IP address of the client by the Security Gateway are not supported.

  • Realms

    Realms are not supported. The client uses “Legacy authentication”.

  • Machine Authentication

    Machine authentication is not supported.

  • Two-Factor Authentication

    Two-Factor Authentication is not supported.

  • Encryption Domain

    Encryption domain changes must deploy on the client side with configuration file changes in some scenarios.

  • Advanced Remote Access features are not supported

    • Certificate enrollment.

    • Link Selection.

    • Location Awareness.

    • Multiple Entry Point (MEP).

    • Secondary Connect.

    • Secure Configuration Verification (SCV).

    • Visitor Mode.

  • IPv6

    IPv6 is not supported.

  • Certificate Usage

    The customer deploys the certificates.

  • Certificate Authentication

    Certificate authentication with ICAClosed Internal Certificate Authority. A component on Check Point Management Server that issues certificates for authentication. is only supported without a CRL check.