lan to lan ipsec vpn - westermo sales · between a westermo mrd-310 3g router and a westermo dr-250...

www.westermo.comLAN to LAN IPsec MRD-310 to DR-250 www.westermo.com

Application Note

LAN to LAN IPsec VPNConnecting the MRD-3xx 3G router to the DR-250 router with IPSec

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Application Note

IPsec VPN

A virtual private network (VPN) is a private data network that makes use of thepublic telecommunication infrastructure, maintaining privacy through the use of atunnelling protocol and security procedures. A virtual private network can becontrasted with a system of owned or leased lines that can only be used by onecompany. The main purpose of a VPN is to give the company the samecapabilities as private leased lines at much lower cost by using the shared publicinfrastructure. Phone companies have provided private shared resources for voicemessages for over a decade. A virtual private network makes it possible to havethe same protected sharing of public resources for data.

IPsec is a suite of protocols for providing peer authentication without transmittingthe actual keys. Confidentiality using encryption and integrity ensuring that thereceived data can only come from the authenticated peer and has not beenaltered in any way.

IPsec Encrypting Security Payload tunnels also provide transparency for all nodesand applications using IP and only the VPN gateways needs to be configured tosecurely connect geographically separated networks.

Firstly we will describe and determine all the parameters necessary for thisconfiguration. These values will be written into the “IPsec Network setup table”

The numbers and parameter values from the “IPsec Network setup table” will beused throughout this guide while first configuring the responder and then theinitiator.







Application Note

Network setup description

This application note describes how to implement a LAN to LAN IPsec VPN tunnelbetween a Westermo MRD-310 3G Router and a Westermo DR-250 ADSL2+Router.

It is important to decide which of the two routers will be the initiator and which will bethe responder. In nearly all cases, the responder will be a VPN gateway, which islocated at a central location, such as company headquarters. In all cases theresponder must have a publicly accessible IP address to connect across internet.

In this example the MRD-310 has a 3G subscription that dynamically assigns aprivate IP address and is hidden behind a Network Address Translation (NAT)device. As such it can only be the initiator.

The DR-250 uses its ADSL WAN interface. The IP address assigned by the ISP ispublic but not fixed. In order to know the IP address of the DR-250 Router we usethe dynamic DNS service of www.dyndns.org to translate the Fully Qualified DomainName (FQDN) weslab.home.dyndns.org to a routable IP address. The DR-250Router will be the responder.

For authentication we will be using Pre-Shared Key (PSK). Simple and practical forinitial and small-scale VPN configurations it is however very susceptible to socialengineering. Large scale or long-term deployment should use certificates forauthentication.This IPsec configuration uses Internet Key Exchange (IKEv1). If the IP addresses ofboth gateways are fixed or certificates are used it is recommended to use IKE mainmode which takes longer to establish connection but provides a higher level ofsecurity than aggressive mode.In this example the combination of dynamic IP address and preshared key requiresus to use IKE aggressive mode.

IKE supports many different types of identifiers (ID) for this example we have chosentype 2 FQDN.Please review RFC 2407 for further details.

Encapsulated Security Payload (ESP) is the final encrypted tunnel joining the twoLAN together. A ESP tunnel is unidirectional so two tunnels are used for full duplexcommunication. Advanced Encryption Standard (AES) is the recommendedencryption standard to use since it is more secure and more efficient than the older3DES encryption.

This configuration is valid for:Westermo MRD-310/330 firmware version 1.33Westermo DR/MR-250 firmware version 5073






http://www.dyndns.org

http://www.dyndns.org


Application Note

IPsec Network setup table

Internet

APN

ResponderInitiator

192.168.20.0/24 192.168.0.0/24

weslab.home.dyndns.org

192.168.20.200 192.168.0.99

LAN to LAN IPsec tunnel

General

External Address IP or FQDN 1 any 2

weslab.home.dynd

ns.orgInternal IP address 3 192.168.20.0 4 192.168.0.0Internal subnet mask 5 255.255.255.0 6 255.255.255.0ID type 7 2 RFC2407 8 2ID value 9 mrd310 10 dr250PSK 11 123456Certificate 12 13

NAT Traversal 14 YESNAT-T keepalive 15 45Dead Peer Detection 16 YESDPD delay & timeout 17 60s/120sMTU 18 19

IKE phase 1 Mode 20 AggressiveEncryption 21 AES (128)Authentication 22 SHA1Diffie Hellman Group 23 2IKE SA Lifetime 24 28800s

IKE phase 2ESP encryption 25 AES (128)ESP authentication 26 SHA1SA Lifetime 27 28800sPerfect Forward Secrecy 28







Application Note

To enter the Preshared key for the connection we must create a user with the key which is linked to aneroute.Select: Users > User 14The user number has no impact on the VPN configuration but the Name and Password must match the PeerID value and PSK respectively.

DR-250 VPN Configuration

Make sure you have configured the DR-250 router as described in the User Guide.Access the routers web interface.In the left side menu select: Configure > ”VPN Configuration” > ”IKE Responder”Make sure that NAT traversal is enabled.

Remember to save to flash when done making changes.

Press

Press

14

21

2224

9

11







Application Note

DR-250 eroute configurationSelect: Configure > VPN Configuration > IPSEC Eroute 0For the correct ID type to be used set ”Send our ID as FQDN” to Yes.Leave Peer IP/hostname blank to indicate any adddress.Enter the values from the network table.

Remember to save to flash when done making changes.Press

10

26

4

9

25

5

3

6

1

27

8







Application Note

DR-250 WAN interface configurationIn this example the ADSL WAN interface uses bridged ethernet and the WAN interface becomes Ethernet 4.Select: Configure > ADSL Interface > ETH 4 BridgedSet the IPSec: parameter to ”ON-Remove SA when link down”

DR-250 firewall configurationWhen the IPsec VPN has been configured correctly we should only allow IPsec connections on the WANinterface.Add the entries below to open IKE udp ports 500 and 4500, IP protocol 50 (ESP) and finally all configurederoutes.There is an explicit end rule that blocks everything else.Once completed activate the firewall on the WAN interface (ETH 4).Save configuration and reboot the router.







Application Note

MRD-310 Initiator VPN configurationMake sure you have configured your MRD-3xx 3G router as described in the User Guide.Access the routers web interface and select VPN in the top menu followed by ”IPsec VPN” in the sub menu.

to start configure a new VPN tunnel.Press

The Local interface should be WLS for the wireless 3G/GPRS interface.Press

Press

2







Application Note

Configure the authentication for Internet Key Exchange (IKE) and Dead Peer Detection.The ID must be preceeded with a @ sign to indicate a type 2 or 3 ID (RFC2407) string.

Press

Press

21 22 23

24

25

27

2628

Next configure Phase 1 and Phase 2 encryption and proposal for the tunnel.

20

11

10

9

16

17







Application Note

Finally we set NAT traversal since our MRD-310 has a private IP address dynamically assigned fromthe 3G provider.Set Enabled, to start the IPsec VPN connection.

Press

Press

LAN to LAN IPsec must know which IP packets to protect so these must be specified in tunnel networksaddress with subnet address/subnet mask. LAN subnet will apply the subnet and mask configured on theEthernet port of the MRD-310

4

3

18

14 15







Application Note

Diagnostics

In the DR-250 you can configure a high level of debug detail for troubleshooting.Select: FULL MENU > Configure > AnalyserTurn the Analyser on and select IKE debug.The debug output can be viewed by selecting: FULL MENU > Status > Analyser Trace

In the MRD-310Select: Status > VPN for details about the VPN status.Further information is available in the System Log.







Application Note

IPsec Network setup table

Initiator ResponderGeneral

External Address IP or FQDN 1 2

Internal IP address 3 4

Internal subnet mask 5 6

ID type 7 RFC2407 8

ID value 9 10

PSK 11

Certificate 12 13

NAT Traversal 14

NAT-T keepalive 15

Dead Peer Detection 16

DPD delay & timeout 17

MTU 18 19

IKE phase 1 Mode 20

Encryption 21

Authentication 22

Diffie Hellman Group 23

IKE SA Lifetime 24

IKE phase 2ESP encryption 25

ESP authentication 26

SA Lifetime 27

Perfect Forward Secrecy 28

Internet

APN

ResponderInitiator

LAN to LAN IPsec tunnel







Application Note

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Technical SupportIf you require assistance with any of the instructions in this application note you cancontact Westermo as follows:






http://www.westermo.se

http://www.westermo.se

mailto:[email protected]


http://www.westermo.fr

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lan to lan ipsec vpn - westermo sales · between a westermo mrd-310 3g router and a westermo dr-250...

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