Tag Archives: gateway to gateway

Cisco ASA Site to Site VPN ‘Using ASDM’

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KB ID 0000072

Problem

Note: This is for Cisco ASA 5500, 5500-x, and Cisco Firepower devices running ASA Code.

Do the same from command line

Below is a walk-through for setting up one end of a site to site VPN Tunnel using a Cisco ASA appliance – Via the ASDM console. Though if (like me) you prefer using the Command Line Interface I’ve put the commands at the end.

click image for full subnet information

Solution

VPN Setup Procedure carried out on ASDM 6.4

Note: The video above uses IKE v1 and IKE v2, in reality you would choose one or the other, and for IKE v2 both ASA 5500 firewalls need to be running OS 8.4(1) or above.

VPN Setup Procedure carried out on ASDM 5.2

1. Open up the ADSM console. > Click Wizards > VPN Wizard.

2. Select “Site-to-Site VPN” > Next.

3. Enter the Peer IP address (IP of the other end of the VPN tunnel – I’ve blurred it out to protect the innocent) > Select “Pre Shared Key” and enter the key (this needs to be identical to the key at the other end. > Give the tunnel group a name or accept the default entry of its IP address. > Next.

4. Choose the encryption protocol (DES, 3DES, AES-128, AES-192, or AES256), choose the Authentication Method (SHA or MD5), and choose the Diffie Hellman Group (1, 2, 5 or 7). Note the other end must match, this establishes phase 1 of the tunnel. > Next.

5. Now select the Encryption Protocols (DES, 3DES, AES-128, AES-192, or AES256), choose the Authentication method (SHA, MD5 or None). Note this is for phase 2 and will protect the encrypted traffic “In Flight”. > Next.

6. Now you need to specify what traffic to encrypt, on the left hand side enter the network or host details (of what’s behind the ASA you are working on), and on the right hand side the IP address of the network or host that’s behind the other VPN endpoint.  Note the other end should be a mirror image. > Next.

7. Review the Settings (Note I’ve blurred the IP address out again) > Next.

8. Back at the ASDM console commit the settings to the ASA memory, Click File > “Save Running Configuration to Flash.”

ASA 5500 VPN Setup from command line

[box]

object network Site-A-SN
subnet 192.168.1.0 255.255.255.0
object network Site-B-SN
subnet 192.168.2.0 255.255.255.0
nat (inside,outside) source static Site-A-SN Site-A-SN destination static Site-B-SN Site-B-SN
access-list outside_1_cryptomap extended permit ip object Site-A-SN object Site-B-SN
crypto ipsec ikev1 transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
crypto map outside_map 1 match address outside_1_cryptomap
crypto map outside_map 1 set pfs
crypto map outside_map 1 set peer {Other Ends IP Address}
crypto map outside_map 1 set ikev1 transform-set ESP-3DES-SHA
crypto ikev1 enable outside
crypto ikev1 policy 10
authentication pre-share
encryption 3des
hash sha
group 2
lifetime 86400
tunnel-group {Other Ends IP Address} type ipsec-l2l
tunnel-group {Other Ends IP Address} ipsec-attributes
ikev1 pre-shared-key 12345678901234567890asdfg

[/box]

ASA 5500 VPN for Version 8.2 and older firewalls

[box]

access-list outside_20_cryptomap extended permit ip 10.254.254.0 255.255.255.0 10.1.0.0 255.255.0.0
access-list inside_nat0_outbound extended permit ip 10.254.254.0 255.255.255.0 10.1.0.0 255.255.0.0
nat (inside) 0 access-list inside_nat0_outbound
crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
crypto map outside_map 20 match address outside_20_cryptomap
crypto map outside_map 20 set pfs
crypto map outside_map 20 set peer {Other Ends IP Address}
crypto map outside_map 20 set transform-set ESP-3DES-SHA
crypto map outside_map interface outside
crypto isakmp enable outside
crypto isakmp policy 10
authentication pre-share
encryption 3des
hash sha
group 2
lifetime 86400
tunnel-group {Other Ends IP Address} type ipsec-l2l
tunnel-group {Other Ends IP Address} ipsec-attributes
pre-shared-key 12345678901234567890asdfg

[/box]

 

Related Articles, References, Credits, or External Links

Original article written 09/11/09

Troubleshooting Phase 1 Cisco Site to Site (L2L) VPN Tunnels

Troubleshooting Phase 2 Cisco Site to Site (L2L) VPN Tunnels

Cisco PIX 500 – IPSEC Site to Site VPNs (v6)

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KB ID 0000611 

Problem

Note: This is for firewalls running an operating system BEFORE version 7, if you have an PIX running version 7 or above go here instead. I’ll run though he commands first and then the configuration from PDM at the end.

Solution

PIX 500: Configure a site to site VPN from command line

1. Connect to the PIX, go to “enable mode”, then to “Configure terminal mode”

[box]

User Access Verification

Password:
Type help or '?' for a list of available commands.
PetesPIX> enable
Password: ********
PetesPIX# configure Terminal
PetesPIX(config)#

[/box]

2. I’m assuming the network BEHIND the PIX 500 is 192.168.124.0/24 and the network at the far end of the tunnel is 192.168.123.0/24. So I’m going to create two ACL’s one to tell the PIX that this traffic should be encrypted, and the second to tell the PIX NOT to perform NAT on the VPN traffic.

Note: Yes I can use one ACL, but having two makes it easier to troubleshoot any VPN problems.

[box]

PetesPIX(config)# access-list VPN_CRYPTO_ACL permit ip 192.168.124.0 255.255.255.0 192.168.123.0 255.255.255.0
PetesPIX(config)# access-list VPN_NO_NAT line 1 permit ip 192.168.124.0 255.255.255.0 192.168.123.0 255.255.255.0

[/box]

3. Now I’ve got an ACL that will stop performing NAT I need to add it as a “Nat 0” (this means don’t perform NAT).

Note: Check to make sure you do not already have a nat(inside) 0 xxx command, if you do, use the SAME ACL that is already in use.

[box]

PetesPIX(config)# nat (inside) 0 access-list VPN_NO_NAT

[/box]

4. To set up all the VPN parameters you need to create a crypto map. In the example below I set the peer IP (the firewall at the other end of the tunnel), to 81.81.81.81. Then I tie it to the ACL I created earlier (VPN_CRYPTO_ACL). I’ve set the encryption and hashing used for the tunnel to 3DES and SHA (These will be used for IPSec (Phase 2)). Set the timeouts for the tunnel, and finally apply the cryptomap I’ve just created, to the outside interface.

[box]

PetesPIX(config)# crypto map VPN_CRYPTO_MAP 20 set peer 81.81.81.81
PetesPIX(config)# crypto map VPN_CRYPTO_MAP 20 match address VPN_CRYPTO_ACL
PetesPIX(config)# crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
PetesPIX(config)# crypto map VPN_CRYPTO_MAP 20 set transform-set ESP-3DES-SHA
PetesPIX(config)# crypto map VPN_CRYPTO_MAP 20 set security-association lifetime seconds 28800 kilobytes 4608000
PetesPIX(config)# crypto map VPN_CRYPTO_MAP interface outside

[/box]

5. The next command lets VPN traffic bypass any other ACLs configured on the firewall.

[box]

PetesPIX(config)# sysopt connection permit-ipsec

[/box]

6. I’m using a “shared secret” that also needs to be setup on the other end of the tunnel. As I said earlier the peer IP is 81.81.81.81.

[box]

PetesPIX(config)# isakmp key 123456 address 81.81.81.81 netmask 255.255.255.255 no-xauth no-config-mode

[/box]

7. To establish the VPN phase 1 (ISAKMP) the devices at both ends of the tunnel need a matching ISAKMP policy. I’ve already set up my shared secret, the first line lets the other end know that’s how we will be communicating. Then once again I’m using 3DES and SHA. I’m telling the system to use Diffie Hellman group 2 for the secure key exchange, and then binding this policy to the outside interface.

Note: If you are interested on how all this stuff works see here

[box]

PetesPIX(config)# isakmp policy 20 authen pre-share
PetesPIX(config)# isakmp policy 20 encrypt 3des
PetesPIX(config)# isakmp policy 20 hash sha
PetesPIX(config)# isakmp policy 20 group 2
PetesPIX(config)# isakmp enable outside

[/box]

8. Then save the changes with a write mem command.

[box]

PetesPIX# write mem
Building configuration...
Cryptochecksum: 79745c0a 509726e5 b2c66028 021fdc7d

7424 bytes copied in 1.710 secs (7424 bytes/sec)
[OK]
PetesPIX#

[/box]

PIX 500: Configure a site to site VPN from the PDM

1. To connect to the PDM you are going to need two things, an OLD browser (IE6) and an OLD version of Java. Select Wizards > VPN Wizard.

2. Site to Site > Next.

3. Set the Peer (Device at the other end of the tunnel) and a shared secret that you will also use at the other end > Next.

4. Set the policy that will be used for phase 1 > Next.

5. Now the phase 2 policy > Next

6. Enter the network behind the PIX > Next.

7. Enter the network at the far end of the tunnel > Finish.

8. Finish by saving the changes > File > Save running configuration to flash.

Related Articles, References, Credits, or External Links

Set up a PIX Firewall with the PDM

PIX 506E and 501 Firewall Image and PDM Upgrade

SmoothWall site to site (IPSEC) VPN to Cisco ASA

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KB ID 0000436 

Problem

You would like to put in a site to site VPN from a site that has a SmoothWall firewall to another site that has a Cisco ASA.

Note: This procedure was carried out on a SmoothWall UTM 1000 Series appliance, and uses a pre-shared key to authenticate the VPN.

Solution

1. For The Cisco end of the configuration, you can configure it from command line see here, or from the ASDM see here..

2. Connect to the SonicWall’s web management console. Navigate to VPN > IPSEC subnets.

2. Set as follows,

Name: Can be anything give it a recognisable name.
Enabled: Tick.
Local IP : Leave blank.
Local Network: The network behind the SmoothWall.
Local ID Type: Local IP
Local ID Value: Leave blank.
Remote IP or Hostname: The outside IP of the Cisco ASA.
Remote Network: The subnet address behind the Cisco ASA.
Remote ID Type: User Specified IP Address.
Remote ID value: The outside IP of the Cisco ASA.
Authenticate by: Preshared Key.
Preshared Key: The same key you entered on the Cisco ASA e.g. This1sak3y
Preshared Key again: Repeat above.
Use Compression: Leave un-ticked.
Initiate the connection: Tick.

Advanced Options

Local Certificate: Default.
Interface: PRIMARY.
Perfect Forward Secrecy: Tick.
Authentication type: ESP
Phase 1 cryptographic algo: 3DES
Phase 1 hash algo: SHA
Phase 2 cryptographic algo: 3DES
Phase 2 hash algo: SHA
Key Life: 60.
IKE Lifetime: 30

3. Finally press “Add”.

Note: To edit an existing tunnel, in the summary at the bottom place a tick in the “Mark” box then click “Edit”.

4. Normally that should be all you need to do, however you may also need to allow zone bridging, select networking > zone bridging.

5. Set as follows,

Source Interface: IPSec
Destination interface: Port that the hosts inside the SmoothWall are plugged into.
Bi-directional: Tick.
Protocol: ALL
Source IP: 0.0.0.0/0
Destination IP: The subnet behind the SmoothWall.
Service: User Defined
Port: Leave Blank
Comment: Put in a sensible text comment.
Enabled: Tick

6. Finally press “Add”.

Note: To edit an existing zone bridge, in the summary at the bottom place a tick in the “Mark” box then click “Edit”.

 

Related Articles, References, Credits, or External Links

NA

 

Cisco ASA 5500 – Reset / Recycle VPN Tunnels

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KB ID 0000586 

Problem

I’ve been asked this before and it came up on EE today, basically you have a site to site VPN tunnel and you either want to restart it or reset it.

Solution

Cisco ASA Reset ALL VPN Tunnels

1. Connect to your ASA, then to reset ALL your ISAKMP VPN tunnels use the following command;

[box] clear crypto isakmp sa [/box]

In the example below I’ve reset ALL my tunnels. I had a constant ping running across the VPN, and it only dropped one packet before the tunnel established again.

WARNING: This will reset ALL ISAKMP VPN tunnels (both site to site, and client to gateway).

Cisco ASA Reset One VPN Tunnel

1. If you just want to reset one site to site VPN then you need to reset the IPSEC SA to the peer (IP Address of the other end of the tunnel). Use the following command;

[box] clear ipsec sa peer X.X.X.X [/box]

Unlike above, in the example below I’ve reset just ONE tunnel. I had a constant ping running across the VPN, and it only dropped one packet before the tunnel established again.

Cisco ASA Check VPN Uptime

Just to prove this isn’t all smoke an mirrors, after the tunnel has re-connected you can check its uptime with the following command;

[box] show vpn-sessiondb detail l2l [/box]

 

Related Articles, References, Credits, or External Links

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