Create A VPN Between An Allied Telesis Router And A Microsoft

How To | Create A VPN Between An Allied Telesis Router
And A Microsoft Windows XP 1 Client,
Without Using NAT-T
1. Internet Explorer and Windows are registered trademarks of Microsoft
Corporation in the United States and other countries.
Introduction
This document describes how to provide secure remote access through IP security (IPSec)
Virtual Private Networks (VPN).
This VPN solution provides your office with secure internet access and firewall protection, plus
remote encrypted VPN access for staff who work from home.
You should use the companion Note How To Create A VPN Between An Allied Telesis Router And A
Microsoft Windows XP Client, Using NAT-T instead, if:
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the Allied Telesis router is connected to the Internet through a NAT gateway device, such as
an ADSL modem, and/or
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you want to let travelling staff connect to your office from such places as hotel rooms.
This companion How To Note is available from www.alliedtelesis.com/resources/literature/
howto.aspx.
Consider the following typical scenario:
You are the manager of a small business and you have purchased an AR415S for your small office
premises. You have five PCs networked together with a server in your office. You intend to use
your AR415S as your Internet gateway and for it to provide firewall protection.
You also have people who sometimes work from home. You would like these staff members to
have secure (encrypted) remote access through the Internet to the servers in your office, to
allow them to access files, the private Intranet, and business email.
Each staff member has a laptop or PC with Windows XP installed.
This document describes how to configure the Windows system to use IPSec VPN to connect
to your office through the AR415S router.
When your staff want to connect to the office they simply use the VPN icon on their desktop to
initiate the IPSec VPN connection.
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Which products and releases does it apply to?
Which products and releases does it apply to?
The following Allied Telesis routers are most suitable as VPN gateways because they have fast
hardware encryption support and high performance:
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AR415S, AR44xS series, and AR450S
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AR750S and AR770S
The AR415S achieves up to 90 Mbps throughput with 3DES or AES encryption.
You can also use older routers as VPN gateways, but they will not have as high performance. The
older routers depend on either the Encryption Mini Accelerator Card (EMAC) or the
Encryption PCI Accelerator Card (EPAC) to perform encryption. They include:
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AR725, AR745, AR720 and AR740 routers
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AR410 series routers
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AR300 series routers
Finally, you can also use the Rapier 24 and Rapier 24i switches as VPN gateways, but this is
usually not a recommended practice. Doing so means you will lose wire-speed switching of data,
because all traffic needs to be inspected by the firewall and IPSec at CPU processing speed.
Encryption algorithms such as 3DES and AES require a feature licence. This is included on some
models. See your Allied Telesis representative for more information.
The configuration is supported on all AlliedWare versions since 2.3.1 and was tested using
Microsoft Windows XP Professional or Home Edition, Service Pack 1a.
Related How To Notes
The following How To Notes give other VPN configurations for interoperating with a Microsoft
Windows VPN client:
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How To Create A VPN Between An Allied Telesis Router And A Microsoft Windows XP Client, Using
NAT-T
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How To Create A VPN Between An Allied Telesis Router And A Microsoft Windows 2000 Client,
Without Using NAT-T
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How To Create A VPN Between An Allied Telesis Router And A Microsoft Windows 2000 Client, Using
NAT-T
The following How To Notes give other VPN configuration examples:
2
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How To Configure VPNs In A Corporate Network, With Optional Prioritisation Of VoIP
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How To Troubleshoot a Virtual Private Network (VPN)
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How To Configure A VPN Between Microsoft ISA Server 2004 And An Allied Telesis Router Client
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How To Use The Allied Telesis GUI Wizard To Create A Site-to-Site VPN Through A NAT Gateway
Device
Security issue
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How To Use The Allied Telesis GUI Wizard To Create A Site-to-Site VPN
(Use this Note when the VPN does not go through a NAT gateway device)
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How To Create A VPN Between An Allied Telesis And A SonicWALL Router, With NAT-T
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How To Create A VPN Between An Allied Telesis And A NetScreen Router
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How To Configure Some Basic Firewall And VPN Scenarios
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How To Configure Some Advanced Features On Your ADSL Router
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How To Configure VoIP And Data Over A Meshed IPsec VPN
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How To Configure IPv6 Support For IPsec VPNs
How To Notes are available from www.alliedtelesis.com/resources/literature/howto.aspx.
Security issue
Since this Windows VPN solution is usually used to allow remote access into corporate
networks, a common security concern is “what happens if the remote laptop or PC is stolen or
falls into unauthorised hands?” This is particularly a concern because the VPN connection is
enabled through the standard dial-up networking window that allows username and passwords
to be saved.
A solution to this security concern is to disable the standard behaviour that allows passwords to
be saved. VPN users will then have to enter their password each time they connect.
If you would like to implement this security measure, refer to Microsoft Knowledge Base article
172430 by following this link: support.microsoft.com/default.aspx?scid=172430.
This solution works on both Windows 2000 and Windows XP.
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Example network
Example network
The following figure shows an example of a network that could use this configuration.
Windows XP Professional
or Home Edition
dial-up modem
remote
teleworker
DSL
remote
teleworker
dial-up modem
remote
teleworker
2 MB pipe
remote
teleworker
Internet
Office PCs
Small Office
remote
teleworker
office’s public
IP address
VPN router
cable modem
network.eps
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Configuring the router > Perform initial security configuration on the router
Configuring the router
This section contains a script file for running IPSec encapsulating L2TP on a Head Office AR400
series router, configured to support IPSec remote PC clients.
Using this script involves the following steps:
1. "Perform initial security configuration on the router", on this page.
2. Make a copy the script, which starts on page 6. Name it (for example) vpn.cfg.
3. Personalise IP addresses, passwords etc in the script, so that they apply to your network.
Placeholders for these are indicated in the script by text within < >.
4. Load the script onto the router using ZMODEM or TFTP.
5. "Set the router to use the configuration" on page 8.
6. Restart the router or activate the script.
Perform initial security configuration on the router
Before loading the configuration, you need to do the following steps.
1. Define a security officer.
add user=secoff password=<your-password> priv=securityofficer
This command must be in the configuration script as well.
2. Enable system security. Unless you do this, rebooting the router destroys encryption keys.
enable system security
3. Log in as the security officer.
login secoff
4. Generate a random key.
create enco key=1 type=general value=<alphanumeric-string>
Note the value of the string you have entered so that you can load it on the PC clients. This
shared key will be used to encrypt ISAKMP negotiation.
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Configuring the router > The configuration script
The configuration script
Note:
Comments are indicated in the script below using the # symbol.
Placeholders for IP addresses, passwords, etc are indicated by text within < >
set system name=”IPSec Gateway”
# The command below shows the Security Officer inactive timeout delay.
# The default is 60 seconds. During setup you can instead use 600
# seconds if desired.
set user securedelay=600
# The incoming L2TP calls will be CHAP authenticated.
# They may be authenticated against the router's user database as
# configured below, or against a RADIUS Server if configured.
add user=dialin1 pass=friend1 login=no
add user=dialin2 pass=friend2 login=no
add user=dialin3 pass=friend3 login=no
add user=dialin4 pass=friend4 login=no
add user=secoff pass=<your-password> priv=securityOfficer login=yes
set user=secoff description=”Security Officer Account”
# If RADIUS server support is needed, use a line such as this:
# add radius server=<your-RADIUS-server-address> secret=<secret-key>
# All dynamic incoming L2TP calls will associate with this PPP template
# as indicated below.
create ppp template=1 bap=off ippool="ip" authentication=chap echo=10
lqr=off
# To cater for dynamic creation of incoming L2TP calls enter the
# following commands.
enable l2tp
enable l2tp server=both
add l2tp ip=1.1.1.1-255.255.255.254 ppptemplate=1
# The IP address allows for any valid Internet address.
enable ip
add ip int=vlan1 ip=<office-private-LAN-address>
add ip int=eth0 ip=<office-Internet-address> mask=<appropriate-mask>
# The default route to the Internet.
add ip route=0.0.0.0 mask=0.0.0.0 int=eth0
next=<your-Internet-gateway-or-ISP-next-hop-address>
# The IP pool addresses are the internal address ranges you want to
# allocate to your IPSec remote PC clients
# (e.g. ip=192.168.8.1-192.168.8.254).
create ip pool=ip ip=<pool-range>
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Configuring the router > The configuration script
# Firewall
enable fire
create fire poli=main
create fire poli=main dy=dynamic
add fire poli=main dy=dynamic user=ANY
add fire poli=main int=vlan1 type=private
# Dynamic private interfaces are accepted from L2TP, which are from
# IPSec only.
add fire poli=main int=dyn-dynamic type=private
add fire poli=main int=eth0 type=public
# The firewall allows for internally generated access to the Internet
# through the following NAT definition.
add fire poli=main nat=enhanced int=vlan1 gblint=eth0
# This NAT definition allows Internet access for remote VPN users by
# providing address translation.
add fire poli=main nat=enhanced int=dyn-dynamic gblint=eth0
add fire poli=main rule=1 int=eth0 action=allow prot=udp
ip=<office-Internet-address> port=500
gblip=<office-Internet-address> gblpo=500
# Rule 2 becomes the L2TP tunnel allow rule. Additional security is
# provided by only allowing traffic from IPSec tunnels.
add fire poli=main rule=2 int=eth0 action=allow prot=udp
ip=<office-Internet-address> port=1701
gblip=<office-Internet-address> gblpo=1701 encap=ipsec
create ipsec sas=1 key=isakmp prot=esp encalg=3desouter hashalg=sha
mode=transport
create ipsec sas=2 key=isakmp prot=esp encalg=3desouter hashalg=md5
mode=transport
create ipsec sas=3 key=isakmp prot=esp encalg=des hashalg=sha
mode=transport
create ipsec sas=4 key=isakmp prot=esp encalg=des hashalg=md5
mode=transport
# The ORDER of proposals is important. You should propose the strongest
# encryption first.
create ipsec bundle=1 key=isakmp string=”1 or 2 or 3 or 4”
create ipsec policy=isakmp int=eth0 action=permit lport=500 rport=500
# This is a generic IPSec policy that multiple IPSec remote PC clients
# can connect through.
create ipsec policy=to_HQ int=eth0 action=ipsec key=isakmp bundle=1
peer=any isa=keys
set ipsec policy=to_HQ transport=udp rport=1701
# The following policy allows for internally generated Internet access.
create ipsec policy=Internet int=eth0 act=permit
enable ipsec
create isakmp policy=keys peer=any key=1
set isakmp policy=keys sendd=true
enable isakmp
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Configuring the router > Set the router to use the configuration
Set the router to use the configuration
After loading the configuration onto the switch, set the router to use the script after a reboot. If
you named the script vpn.cfg, enter the command:
set conf=vpn.cfg
If you entered the configuration directly into the command line instead of loading the script, save
the configuration by entering the commands:
create conf=vpn.cfg
set conf=vpn.cfg
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Configuring the VPN client > Create a VPN tunnel from the PC host to the router
Configuring the VPN client
Configuring the Windows XP VPN client involves the following two stages:
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"Create a VPN tunnel from the PC host to the router", on this page
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"Connect to the Head Office" on page 12
Create a VPN tunnel from the PC host to the router
Note:
You need to know the public IP address for the router from your Internet Service
Provider (ISP) for this configuration.
This example assumes that you have already set up your internet connection.
1. On your desktop, click Start > Control Panel.
Make sure you are in Category View, as shown in the following figure. If your computer is in
Classic View, click Switch to Category View in the Control Panel Menu on the left of your
screen.
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Configuring the VPN client > Create a VPN tunnel from the PC host to the router
2. Click Network and Internet Connections > Create a connection to the network at your workplace.
This starts up the New Connection Wizard.
Select Virtual Private Network Connection as shown in the following figure.
3. Click Next.
Type in a name for the connection (e.g. VPN Connection To Head Office) as shown in the
following figure.
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Configuring the VPN client > Create a VPN tunnel from the PC host to the router
4. Click Next.
Assign an associated dialled call or select Do not dial the initial connection. Selecting Do not dial
the initial connection is appropriate if you will have LAN access available before initiating the
VPN call (for example, if you have a cable modem).
5. Click Next.
Enter the name or IP address of the office router. This will be its Public Internet address,
which the ISP will have allocated you.
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Configuring the VPN client > Connect to the Head Office
6. Click Next.
You have now completed creating the connection, as shown in the following figure. If you want
to, check the Add a shortcut to this connection to my desktop check box. Then click Finish.
Connect to the Head Office
1. Double-click the new Head Office icon on your desktop or in “Network Connections” in the
control panel.
2. Enter your user name and password as shown in the following figure. These are the user
name and password that is (or will be) configured on the router’s user database or RADIUS
server.
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Configuring the VPN client > Connect to the Head Office
3. Click Properties.
This opens the Head Office Properties window. Click the Security Tab, as shown in the
following figure.
4. Click the IPSec Settings button.
This opens the IPSec Settings window, as shown in the following figure. Select the Use preshared key for authentication checkbox and enter your pre-shared key. The pre-shared key
needs to be the same ISAKMP pre-shared key as is defined on the router ("Generate a
random key." on page 5).
5. Click OK.
This returns you to the Head Office Properties window.
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Configuring the VPN client > Connect to the Head Office
6. Click the Networking Tab, as shown in the following figure. In the Type of VPN drop-down
box, select L2TP IPSec VPN.
7. Click OK. This completes the configuration of the L2TP client. To connect to the office, click
Connect. Note that the connection will fail if the router has not yet been configured.
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Testing the tunnel > Checking the connection from the Windows client
Testing the tunnel
The simplest way to tell if traffic is passing through the tunnel is to perform a traceroute from
the Windows XP client to a PC in the router’s LAN. To do this, use the following command at
the command prompt on the Windows XP client:
tracert <ip-address>
If traffic goes through the tunnel, the traceroute may display IP addresses from one or both
peers’ private networks and public interfaces. If it shows other public IP addresses, then traffic is
not passing through the tunnel.
Checking the connection from the Windows client
To check your connection details, right-click on your connection icon (e.g. Virtual Private
Connection to Head Office) in the Network Connections folder, or on your desktop.
Click Status. Then click the Details tab to check your connection information, as shown in the
following figure.
Troubleshooting
If your tunnel is not working, see the How To Note How To Troubleshoot A Virtual Private Network
(VPN).
This How To Note has detailed information about testing and troubleshooting VPNs on the
router.
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Closing the connection
To close your connection, right-click on your connection icon and click Disconnect. The
following figure shows this.
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© 2007 Allied Telesis, Inc. All rights reserved. Information in this document is subject to change without notice. Allied Telesis is a trademark or registered trademark of Allied Telesis, Inc. in the United States and other countries.
All company names, logos, and product designs that are trademarks or registered trademarks are the property of their respective owners.
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