I was asked to setup a VPN to help out a colleague this week. When I had a look, one end turned out to be an Edge Gateway, I wasn’t that concerned, I’d done similar things in my prior role, I just didn’t have access to the vCloud or VMware at this datacenter.
Depite my best efforts on the ASA, the tunnel refused to come up, it took a little looking ‘under the covers’ to accurately diagnose the problem. But to save you my pain, I’ll post the setup of both ends so yours will be a little less stressful.
VMware Edge Gateway VPN Setup
Locate the Edge Gateway in vCloud Director > VPN > Create new VPN > Tick ‘Enable This VPN‘ configuration > Set the local and remote networks > Local ID is the local public IP of the Edge Gateway > Remote ID is the pubic IP of the Cisco ASA > Set the encryption protocol as AES256 > Copy the pre-shared-key (Warning: some browsers wont select all of the key, and you will end up characters short, make sure you have it all!) > OK.
On the ‘Firewall’ Tab allow all traffic TO and FROM the remote subnet, (behind the Cisco ASA).
Note: There no need to make a NAT Exemption.
Cisco ASA VPN Setup (For Edge Gateway)
Note: The version of Edge Gateway I was using, was using (once AES256 is selected)
IKE Version: 1
Encryption:AES-256
Hashing: SHA
Diffie Hellman: Group 2
Perfect Forward Secrecy: Enabled (group 2)
I’m aware that newer Edge Gateways support IKEv2 but debugging the incoming requests told me mine was using IKEv1.
You DO NOT have any existing VPNs configured, (if you do, change the name of the CRYPTO-MAP (above) to match the name of your cryptomap and use a higher number, e.g. ‘outside_map 2‘).
Troubleshooting Edge Gateway End of the VPN
You need access to the underlying VMware infrastructure > Select Networking and Security > Locate the NSX Edge > VPN > IPsec VPN > Show IPsec Statistics > Here you can see some meaningful error massages if theres a problem.
Troubleshooting Cisco ASA End of the VPN
I’ve covered this to death in the past, so rather than reinvent the wheel;
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.”
I’ve done thousands of firewall VPN’s but not many that terminate on Cisco Routers. It’s been a few years since I did one, and then I think I was a wuss and used the SDM. So when I was asked to do one last week thankfully I had the configs ready to go.
I’m going to use the IP addresses above, and my tunnel will use the following settings;
3. Create a ‘Crypto map’ that is used to apply the phase 2 settings to an interface.
[box]
R1(config)#crypto map VPN-C-MAP 10 ipsec-isakmp
% NOTE: This new crypto map will remain disabled until a peer
and a valid access list have been configured.
R1(config-crypto-map)#set peer 1.1.1.2
R1(config-crypto-map)#set transform-set VPN-TS
R1(config-crypto-map)#match address VPN-ACL
[/box]
4. Apply that crypto map to an interface, (usually the Internet facing one).
[box]
R1(config-crypto-map)#interface Serial0/1/0
R1(config-if)#crypto map VPN-C-MAP
*Jan 3 07:16:26.785: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON
R1(config-if)#exit
R1(config)#
[/box]
5. In most cases your router will be doing NAT, if so you will need to change the ACL that is looking after the NAT for you, look in your running config for something that looks like the following;
[box]
R1#show run
Building configuration...
Current configuration : 1249 bytes
------------output removed for the sake of space------------
!
ip nat inside source list 100 interface Serial0/1/0 overload
!
access-list 100 permit ip 10.10.10.0 0.0.0.255 any
!
------------output removed for the sake of space------------
!
line aux 0
!
[/box]
6. To stop our VPN traffic getting NATTED, we need to put a deny in that ACL, and put it before that permit statement. Remember:
Permit=Perform NAT
Deny=Don’t perform NAT
On this router (unlike the ASA‘s that I’m more used to), there is no option to define an ACL line number. So its easier to remove the existing one, add the new line then put the original one back. Finally save the changes.
[box]
R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#no access-list 100 permit ip 10.10.10.0 0.0.0.255 any
R1(config)#access-list 100 deny ip 10.10.10.0 0.0.0.255 20.20.20.0 0.0.0.255
R1(config)#access-list 100 permit ip 10.10.10.0 0.0.0.255 any
R1(config)#exit
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#write mem
Building configuration...
[OK]
[/box]
7. Now at the other site, the config should be a mirror image. I will post it in its entirety, so you can copy and paste it into the router, I will highlight the bits you need to check and change in red.
[box]
crypto isakmp policy 1
encr aes
hash sha
authentication pre-share
group 2
lifetime 86400
crypto isakmp key SecretK3y address 1.1.1.1
ip access-list extended VPN-ACL
permit ip 20.20.20.0 0.0.0.255 10.10.10.0 0.0.0.255
crypto ipsec transform-set VPN-TS esp-aes esp-sha-hmac
crypto map VPN-C-MAP 10 ipsec-isakmp
set peer 1.1.1.1
set transform-set VPN-TS
match address VPN-ACL
interface Serial0/1/0
crypto map VPN-C-MAP
no access-list 100 permit ip 20.20.20.0 0.0.0.255anyaccess-list 100 deny ip 20.20.20.0 0.0.0.255 10.10.10.0 0.0.0.255access-list 100 permit ip 10.10.10.0 0.0.0.255 any
[/box]
8. Test your VPN with the following commands. Note: you need to send some traffic over the VPN before it will establish!
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show crypto isakmp sa
show crypto ipsec sa
[/box]
WARNING: If you have an ACL applied to the routers outside interface, you will need to allow in the Peer IP, like so;
[box]
ip access-list extended outside-in
permit esp host 1.1.1.1 any
permit udp host 1.1.1.1 any eq isakmp
permit udp host 1.1.1.1 any eq non500-isakmp
[/box]
If you do not, the other end will fail Phase 1 with a WAIT_MSG_3 Error!
Related Articles, References, Credits, or External Links
As with most things, before you have a hope of fixing something, you will stand a better chance if you know how it works in the first place. Below is a quick run though of what’s happening with your site to site VPN‘s and how they work.
For the entire process we will have two Cisco ASA 5500 firewalls and a site to site VPN.
Solution
What’s an Initiator and a Responder?
1. Our Laptop 192.168.1.50 wants to talk to a server on the other site at 172.16.1.50
2. To get out of the local network the Laptop goes through the ASA at its local site, The ASA knows that traffic destined for 172.16.1.50 needs to be sent down the VPN tunnel, so it needs to bring up the tunnel. IT BECOMES THE INITIATOR, contacts the ASA on the other site THAT BECOMES THE RESPONDER.
3 Once that’s complete the tunnel is up and traffic can pass.
So how does it bring up the Tunnel?
To establish an ISAKMPVPN tunnel 3 things have to happen.
1. Phase 1 has to complete.
2. Phase 2 has to complete.
3. The Traffic has to be allowed to pass.
VPN Phase 1 (ISAKMP)
This stage brings up the first secure tunnel (eventually there will be three tunnels) and for it to establish the firewalls need to agree what they are going to do to bring up the tunnel, then Secure the tunnel. This process uses SIX MESSAGES (Note: We are dealing to Main Mode here not Aggressive mode). Both firewalls need a matching Phase 1 Policy to continue. And the Policy is proposed in MESSAGE1 and accepted in MESSAGE2.
A Phase 1 policy consists of,
1. The Authentication method (either a pre shared key or an RSA signature is usual).
5. Lifetime (In seconds before phase 1 should be re-established – usually 86400 seconds [1 day]).
MESSAGE 1
The Initiator sends policies that it proposes to use, for phase 1 to the other ASA.
MESSAGE 2
Providing the responder has a matching policy it will accept one of those proposed by the initiator and send it back in message 2.
Now the two ends have agreed HOW they will establish phase 1, they then need to agree on a “Shared Key” both ends must use the same shared key, but the shared key cant be sent between them because the network link is not secure. To do this they use a Diffie Hellman key exchange, this uses a mathematical process called modular exponentiation, a simple example of how that works (The math’s involved in a real key exchange are much more complicated!).
How Diffie Hellman works (simply)
Problem Site A and Site B need to use the same secret key (which will be a big long number). they cant send that number to each other because if they do it will be seen.
Solution:
Both sites pick a random number, and they have a common number, this common number can be passed between sites, In our example Site A chooses 4 and Site B chooses 5
Both sites use the common number and raise it by the power of the random number they are using so Site A arrives at 16, and Site B at 32.
The sites then send the number they have arrived at, to the other site.
Each site uses the other sites total and raises it to the power of their original random number, this results in them both having the same key, with only the numbers 2, 16 and 32 being passed between them.
Back to our VPN Tunnel
The next two messages are the initiator and responder swapping their Diffie Hellman information, Each side produces a DH Public Key, and mathematically computes a long number called a “Nonce”
MESSAGE 3
The initiator generates a “Public Key” also called the DH Public Value or Xa It also generates a Nonce or Ni and sends both of them to the responder.
MESSAGE 4
The responder generates a “Public Key” also called the DH Public Value or Xb It also generates a Nonce or Nr and sends both of them to the initiator.
At this point both the initiator and the responder can calculate the DH Shared secret key, they then use the DH Secret Key, the “Shared Secret” that is manually entered onto both peers, and the Nonce from the other peer to create 3 DIGITAL KEYS, because of the nature of Diffie Hellman each end will produce the same keys.
Key 1 = SKEYID_d Used to work out any future IPsec keying Key 2 = SKEYID_a Used for data integrity and authentication (IKE) Key 3 = SKEYID_e Used to encrypt all further IKE traffic.
MESSAGE 5
The initiator now sends its ID to the responder (this is either its IP address or a hostname). It also sends a “Hash” this authenticates the initiator to the responder as its made from the SKEYID, the pre-shared key and other information only known to the two peers.
MESSAGE 6
Message 6 is basically the mirror of Message 5, the responder sends its ID (IP or Hostname) Back the the initiator with its “Hash” and authenticates itself back to the initiator.
At this point both peers recalculate the hash they have received from the other peer, and they should both come out the same, if this happens then the IKESA’s are established and phase 1 is complete.
So what’s PFS?
Perfect Forward Secrecy is a method by which new keys are generated, each new key is mathematically linked to the key that came before it, the prior key being a “Grandfather” key. With PFS enabled this link is broken so a key can not be forward/reverse engineered to guess a previous/new key value). Every new negotiation produces a new fresh key.
Once Phase 1 has completed the second stage of the VPN can start. Like phase 1 this state also requires messages to be sent between the peers, IPsec usually executes in “Quick mode” this means that there are only 3 MESSAGES.
Note: If PFS is configured only on one end then it will fail at this point with an “Attribute not supported” error.
MESSAGE 1
The Initiator sends another Hash to the responder, this is similar to the one used in phase 1 but also includes info within this message to guarantee integrity.
4. The SPI – This number is the LABEL for the end of the tunnel the initiator will use for outbound traffic.
Tunnel mode (Tunnel or Transport). A timeout in seconds is specified, as is the ID (usually the subnet of both ends of the tunnel).
MESSAGE 2
The Responder replies with its own “Hash” with the accepted proposal and its own SPI for outgoing encrypted traffic from the responder, and finally its own Key Exchange Payload.
Once this is complete both peers generate new DH secret keys and combine them with the SKEYID_d key from phase 1 to create keys for IPsec encryption.
MESSAGE 3
The final Message is sent from imitator to responder, and serves to inform the responder that its previous message was received.
Once phase 2 is complete IPsec SA’s have been established and the tunnel is up.
Related Articles, References, Credits, or External Links
Site to Site VPN’s either work faultlessly straight away, or involve head scratching and a call to Cisco TAC, or someone like me to come and take a look. If I’m honest, the simplest and best answer to the problem is “Remove the Tunnel from both ends and put it back again”. Just about every VPN tunnel I’ve put in that did not work, was a result of my fat fingers putting in the wrong subnet, IP address or shared secret.
However you can’t always remove the tunnel and start again, especially if you only have control of your end of the tunnel. In that case you need to do some troubleshooting and debugging.
Solution
To Troubleshoot and debug a VPN tunnel you need to have an appreciation of how VPN Tunnels work READ THIS.
Now you have read that you are an expert on IKE VPN Tunnels 🙂
Step 1
To bring up a VPN tunnel you need to generate some “Interesting Traffic” Start by attempting to send some traffic over the VPN tunnel.
User Access Verification
Password:
Type help or '?' for a list of available commands.
PetesASA> enable
Password: ********
PetesASA# show crypto isakmp
[/box]
You may see a lot more information if you have Existing VPN tunnels, but what you are looking for is this,
[box]
IKEv1 SAs:
Active SA: 2
Rekey SA: 0 (A tunnel will report 1 Active and 1 Rekey SA during rekey)
Total IKE SA: 2
1 IKE Peer: 123.123.123.123
Type : L2L Role : initiator
Rekey : no State : MM_ACTIVE <<YOUR SIDE BROUGHT THE VPN UP
There are no IKEv2 SAs
[/box]
If you see MM_ACTIVE (This means phase 1 has completed in Main Mode, and is active) So phase 1 has completed successfully, you need to jump forward and troubleshoot Phase 2.
Note: If you see AG_{something} this means you are trying to bring the tunnel up in aggressive mode!
If there is nothing listed at all – then your side is not even trying to bring up the tunnel. Try and generate a lot of VPN traffic – Like a persistent ping {ping 192.168.1.1 -t} and issue the show crypto isakmp command a few times to be sure. if you never see anything then its not getting as far as phase 1!
If your still reading this, then your problem is with Phase 1, and you have an ISAKMPSA state error.
ISAKMP SA MESSAGE STATES (On the Initiator)
MM_WAIT_MSG2
Message 1 has been sent to the responder but there has been no reply.
Causes:
1. There is no network connectivity to the firewallsecurity device at the other end, can you ping it?
2. The IP address of the far firewall is incorrect in the tunnel-group, issue a “show run tunnel-group” command, check you have a tunnel group with the correct IP address.
3. The IP address in the “Crypto Map” is incorrect, issue a “show run crypto map” command and check the line that ends “crypto map {name} {number} set peer xxx.xxx.xxx.xxx” to make sure.
4. You do not have a matching phase 1 policy with the other end, issue a “show run crypto isakmp” command make sure the other end has a matching policy, if you cant check the other end then generate some VPN traffic, issue the following command and check for the following,
[box]
EXAMPLE PHASE 1 POLICIES DONT MATCH
Password: Type help or ‘?’ for a list of available commands. PetesASA> en Password: ******** PetesASA#debug crypto isakmp 200
<<<<<<<LOTS Of DEBUG TEXT REMOVED>>>>>>>
Apr 01 14:48:48 [IKEv1]: IP = 123.123.123.123, IKE_DECODE RECEIVED Message (msgid=ce4a3ffe) with payloads : HDR + NOTIFY (11) + NONE (0) total length : 56 Apr 01 14:48:48 [IKEv1]: IP = 123.123.123.123, Received an un-encrypted NO_PROPOSAL_CHOSEN notify message, dropping Apr 01 14:48:48 [IKEv1]: IP = 123.123.123.123, Information Exchange processing failed
<<<<<<<LOTS Of DEBUG TEXT REMOVED>>>>>>>
[/box]
MM_WAIT_MSG4
The Phase 1 Policies have been agreed with both peers, the initiator is waiting for the responder to send it its keying information. I’ve seen two things cause this.
1. Different Vendors equipment talking the the ASA, or simply the version of OS on the ASA have been different.
2. There is a comms error, check there’s no router with firewall capabilities in the link.
MM_WAIT_MSG6
If there’s a firewall ‘in-between’ make sure UDP port 4500 is open for both peers.
Check your Pre-Shared Keys match on the ASA issue a “more system:running-config” then keep pressing the space bar till you see the tunnel- group and shared key
Again if you can’t check the other end then issue the following debug and the following will tell you if there is a key mismatch.
This error can also be seen if one end has PFS set and the other end does not. In this case the error will appear and dissapear and the connection is repeatedly “torn down”
e.g
crypto map outside_map 20 set pfs [box]
EXAMPLE PHASE 1 PRE SHARED KEYS DONT MATCH
Password: Type help or ‘?’ for a list of available commands. PetesASA> en Password: ******** PetesASA#debug crypto isakmp 200
<<<<<<<LOTS Of DEBUG TEXT REMOVED>>>>>>>
Apr 01 15:11:47 [IKEv1]: IP = 123.123.123.123, IKE_DECODE RECEIVED Message (msgid=5456d64e) with payloads : HDR + NOTIFY (11) + NONE (0) total length : 56 Apr 01 15:11:47 [IKEv1]: Group = 123.123.123.123, IP = 123.123.123.123, Received an un-encrypted PAYLOAD_MALFORMED notify message, dropping Apr 01 15:11:47 [IKEv1]: Group = 123.123.123.123, IP = 123.123.123.123, Error, peer has indicated that something is wrong with our message. This could indicate a pre-shared key mismatch. Apr 01 15:11:47 [IKEv1]: Group = 123.123.123.123, IP = 123.123.123.123, Information Exchange processing failed
<<<<<<<LOTS Of DEBUG TEXT REMOVED>>>>>>>
[/box]
ISAKMP SA MESSAGE STATES (On the Responder)
MM_WAIT_MSG3
The Phase 1 Policies have been agreed with both peers, the responder is waiting for the initiator to send it its keying information. I’ve seen two things cause this.
1. Different Vendors equipment talking the the ASA, or simply the version of OS on the ASA have been different.
2. There is a comms error, check there’s no router with firewall capabilities in the link.
3. I’ve seen this on a VPN from a VMware Edge Gateway, that had PFS (perfect forward secrecy) enabled, and the ASA did not.
If there’s a firewall ‘in-between’ make sure UDP port 4500 is open for both peers.
Here’s an Example of Phase one completing message by message successfully.
MESSAGE 1 (Leaving the Initiator)
[box]
Apr 01 11:38:51 [IKEv1]: IP = 123.123.123.123, IKE Initiator: New Phase 1, Intf inside, IKE Peer 123.123.123.123 local Proxy Address 192.168.1.0, remote Proxy Address 172.16.1.0, Crypto map (outside_map) Apr 01 11:38:51 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing ISAKMP SA payload Apr 01 11:38:51 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing NAT-Traversal VID ver 02 payload Apr 01 11:38:51 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing NAT-Traversal VID ver 03 payload Apr 01 11:38:51 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing NAT-Traversal VID ver RFC payload Apr 01 11:38:51 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing Fragmentation VID + extended capabilities payload Apr 01 11:38:51 [IKEv1]: IP = 123.123.123.123, IKE_DECODE SENDING Message (msgid=0) with payloads : HDR + SA (1) + VENDOR (13) + VENDOR (13) + VENDOR (13) + VENDOR (13) + NONE (0) total length : 168
[/box]
MESSAGE 2 (Arriving at the Responder)
[box]
Apr 01 11:38:52 [IKEv1]: IP = 123.123.123.123, IKE_DECODE RECEIVED Message (msgid=0) with payloads : HDR + SA (1) + VENDOR (13) + NONE (0) total length : 117
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, processing SA payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, Oakley proposal is acceptable
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, processing VID payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing ke payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing nonce payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing Cisco Unity VID payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing xauth V6 VID payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, Send IOS VID
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, Constructing ASA spoofing IOS Vendor ID payload (version: 1.0.0, capabilities: 20000001)
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, constructing VID payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, Send Altiga/Cisco VPN3000/Cisco ASA GW VID
[/box]
MESSAGE 3 (Leaving the Initiator)
[box]
Apr 01 11:38:52 [IKEv1]: IP = 123.123.123.123, IKE_DECODE SENDING Message (msgid=0) with payloads : HDR + KE (4) + NONCE (10) + VENDOR (13) + VENDOR (13) + VENDOR (13) + VENDOR (13) + NONE (0) total length : 256
[/box]
MESSAGE 4 (Arriving at the Initiator)
[box]
Apr 01 11:38:52 [IKEv1]: IP = 123.123.123.123, IKE_DECODE RECEIVED Message (msgid=0) with payloads : HDR + KE (4) + NONCE (10) + NONE (0) total length : 228
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, processing ke payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, processing ISA_KE payload
Apr 01 11:38:52 [IKEv1 DEBUG]: IP = 123.123.123.123, processing nonce payload
[/box]
MESSAGE 5 (Leaving the Initiator)
[box]
Apr 01 11:38:52 [IKEv1]: IP = 123.123.123.123, Connection landed on tunnel_group 123.123.123.123
Apr 01 11:38:52 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, Generating keys for Initiator...
Apr 01 11:38:52 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, constructing ID payload
Apr 01 11:38:52 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, constructing hash payload
Apr 01 11:38:52 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, Computing hash for ISAKMP
Apr 01 11:38:52 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, constructing dpd vid payload
Apr 01 11:38:52 [IKEv1]: IP = 123.123.123.123, IKE_DECODE SENDING Message (msgid=0) with payloads : HDR + ID (5) + HASH (8) + VENDOR (13) + NONE (0) total length : 84
[/box]
MESSAGE 6 (Arriving at the Initiator)
[box]
Apr 01 11:38:53 [IKEv1]: IP = 123.123.123.123, IKE_DECODE RECEIVED Message (msgid=0) with payloads : HDR + ID (5) + HASH (8) + NONE (0) total length : 64
Apr 01 11:38:53 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, processing ID payload
Apr 01 11:38:53 [IKEv1 DECODE]: Group = 123.123.123.123, IP = 123.123.123.123, ID_IPV4_ADDR ID received 123.123.123.123
Apr 01 11:38:53 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, processing hash payload
Apr 01 11:38:53 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, Computing hash for ISAKMP
Apr 01 11:38:53 [IKEv1]: IP = 123.123.123.123, Connection landed on tunnel_group 123.123.123.123
Apr 01 11:38:53 [IKEv1 DEBUG]: Group = 123.123.123.123, IP = 123.123.123.123, Oakley begin quick mode
Apr 01 11:38:53 [IKEv1 DECODE]: Group = 123.123.123.123, IP = 123.123.123.123, IKE Initiator starting QM: msg id = 26f952ae
Apr 01 11:38:53 [IKEv1]: Group = 123.123.123.123, IP = 123.123.123.123, PHASE 1 COMPLETED
[/box]
Note: You can debug Phase 1 traffic on a particular tunnel, with the following command.
debug crypto condition peer 123.123.123.123
or, simply;
debug crypto isakmp
Phase 1 Debug Errors
[box]
Petes-ASA((config)# debug crypto isakmp
Feb 29 11:49:08 [IKEv1]Group = 123.123.123.123, IP = 123.123.123.123, QM FSM error (P2 struct &0x00007fda92308b10, mess id 0xc02b7a5d)!
Feb 29 11:49:08 [IKEv1]Group = 123.123.123.123, IP = 123.123.123.123, Removing peer from correlator table failed, no match!
Feb 29 11:49:08 [IKEv1]Group = 123.123.123.123, IP = 123.123.123.123, Session is being torn down. Reason: crypto map policy not found
[/box]
This was due to more than one misconfiguration, firstly the source and destination network objects in the interesting traffic ACL were the wrong way round! (Don’t forget to check your static NAT statement as well). And the TRANSFORM SET didn’t match, (sometimes you can see phase one established but then it disappears).
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
[box]
Petes-ASA((config)# debug crypto ikev1
Apr 19 16:36:10 [IKEv1]IP = 123.123.123.123, No Group found by matching OU(s) from ID payload: Unknown
Apr 19 16:36:10 [IKEv1]IP = 123.123.123.123, Trying to find group via IKE ID...
Apr 19 16:36:10 [IKEv1]IP = 123.123.123.123, Trying to find group via IP ADDR...
Apr 19 16:36:10 [IKEv1]IP = 123.123.123.123, Connection landed on tunnel_group 123.123.123.123
Apr 19 16:36:10 [IKEv1 DEBUG]Group = 123.123.123.123, IP = 123.123.123.123, peer ID type 2 received (FQDN)Apr 19 16:36:10 [IKEv1]Group = 123.123.123.123, IP = 123.123.123.123, Unable to compare IKE ID against peer cert Subject Alt Name
Apr 19 16:36:10 [IKEv1 DEBUG]Group = 123.123.123.123, IP = 123.123.123.123, IKE MM Responder FSM error history (struct &0x00007ffd9e230670) <state>, <event>: MM_DONE, EV_ERROR-->MM_BLD_MSG6, EV_COMPARE_IDS-->MM_BLD_MSG6, EV_CERT_OK-->MM_BLD_MSG6, NullEvent-->MM_BLD_MSG6, EV_ACTIVATE_NEW_SA-->MM_BLD_MSG6, NullEvent-->MM_BLD_MSG6, EV_VALIDATE_CERT-->MM_BLD_MSG6, EV_UPDATE_CERT
Apr 19 16:36:10 [IKEv1 DEBUG]Group = 123.123.123.123, IP = 123.123.123.123, IKE SA MM:3a1ed893 terminating: flags 0x01018002, refcnt 0, tuncnt 0
Apr 19 16:36:10 [IKEv1 DEBUG]Group = 123.123.123.123, IP = 123.123.123.123, sending delete/delete with reason message
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The ASA did not like the certificate presented by the remote peer, (Even though is was a good cert issued by NDES). To get past this you need to make a change to the tunnel group.
Petes-ASA((config)# debug crypto ikev1
%ASA-3-717009: Certificate validation failed. Peer certificate key usage is invalid, serial number: 6B00002B3F8571E2605FA02883000100002C3E, subject name: hostname=Petes-Router-Petes-HQ.petenetlive.com.
%ASA-3-717027: Certificate chain failed validation. Certificate chain is either invalid or not authorized.
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The ASA did not like the certificate presented by the remote peer, (Even though is was a good cert issued by NDES). To get past this you need to make a change to the trustpoint on the ASA.
[box]
Petes-ASA(config)# crypto ca trustpoint PNL-Trustpoint
Petes-ASA(config-ca-trustpoint)# ignore-ipsec-keyusage
[/box]
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
[box]
Petes-ASA# debug crypto ikev1
Petes-ASA# Feb 17 12:25:17 [IKEv1]Group = 123.123.123.123, IP = 123.123.123.123, Received encrypted Oakley Main Mode packet with invalid payloads, MessID = 0
Feb 17 12:25:17 [IKEv1]Group = 212.20.251.44, IP = 123.123.123.123, ERROR, had problems decrypting packet, probably due to mismatched pre-shared key. Aborting
Feb 17 12:25:23 [IKEv1]IP = 123.123.123.123, Header invalid, missing SA payload! (next payload = 4)
\
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Amazingly this had nothing to do with a mismatched pre shared key, the other end was set to use PFS (Perfect Forward Secrecy,) and my end (the ASA) was not.
If you have got this far the next step is to troubleshoot Phase 2
Related Articles, References, Credits, or External Links
You want to put in a secure IPSECVPN tunnel from a Cisco ASA Device to a Sonicwall Firewall. Note in this example we will use 3DES for encryption, SHA1 for Hashing, Diffie Hellman Group 2, PFS enabled, and we will use a shared secret (Pre Shared Key).
SonicWALL used in this example is a PRO 3060.
Solution
The main two gotcha’s
Update 12/03/11 Feedback from Wajma Omari:
I would like to add that this configuration will build the Tunnel but one more step needed to enable the Traffic between the two networks and that is by adding ACL from Inside network to the Remote Site Configuration – Firewall – Advanced – ACL Manager – Add – Add ACL and then ADD ACE
Thanks for the very helpful article
Many Thanks for the feedback! Pete
Related Articles, References, Credits, or External Links
Special thanks to David Pounds for his help with the SonicWALL configuration.
You want to establish a site to site VPN from a site with a Cisco ASA firewall, to another site running a Juniper SRX firewall. I had to do this this week, and struggled to find any good information to help.
In the example below I’m configuring the whole thing from a laptop (172.16.254.206) that’s on the Juniper’s site. Use the diagram below, and substitute your own IP addresses and subnet addresses, to get a workable solution for your site.
When the process is complete, I will test it by pinging the host behind the Cisco ASA on the remote site (10.254.254.5).
Solution
Before you begin, I will assume both firewalls are functioning properly and the clients behind them can access internet services (where allowed) through them already.
5. Enter the Local (behind the ASA) network > Then the Remote (behind the Juniper) network > Next.
Note: You can type them in, but if you use the pick-list button you can select ‘inside-network’ for the local, and define a network object for the remote network.
6. Enter a pre shared key, (remember this, you need to enter it on the Juniper).
8. Enable PFS > Tick the box to exempt traffic from NAT > Next.
9. Review the settings > Finish
11. Save the changes > File > Save running Configuration to Flash.
Step 2 – Configure the Juniper SRX (Route Based VPN)
Model used SRX100B version 11.2R4.3
The SRX support two types of VPN
Route based VPN – VPN selection is done based on the route. In this you define a route pointing to the tunnel interface (st0 interface) bound to the VPN.
Policy based VPN – VPN is selected based on the policy.
15. Give the tunnel a name > Set the local zone to trust > Add in the local subnet (behind the Juniper) > Name the Secure Tunnel Interface (just put in a zero) > Set the secure tunnel zone to Untrust > Enter the physical address the VPN will be terminating on, (usually the fe0/0/0.0 interface, but it does not have to be) > Next.
Note: On the Juniper, when specifying a subnet use the short subnet notation, i.e. 192.168.1.0 255.255.255.0 would be 192.168.1.0/24 (if you get stuck use my subnet calculator).
16. Supply the public IP address of the ASA > and add in the subnet at the far end of the tunnel (behind the ASA) > Next.
17. Set the IKE (phase 1) settings to Compatible, Main Mode, enter the same pre shared key you setup in Step 1 (number 6) > Set the IPSEC (phase 2) settings to Compatible, IPsec Perfect Forward Secrecy (PFS) to group 2 > Next.
20. Navigate to IPsecVPN > Auto Tunnel > Phase II > Select your tunnel > Edit > IPsecVPN Options > Tick ‘use proxy identity’ > Enter the local and remote subnets > OK.
21. Navigate to Security > Zones/Screen > Select the untrust zone > Edit > Host Inbound traffic – Interface > Select the physical address that the VPN is terminating on (usually fe-0/0/0.0) > Add IKE as an Interface service > OK.
22. To save the changes > Action > Commit.
23. Test the VPN by attempting to ping a host on the other end.
Juniper SRX Command Line
On the Cisco firewalls I prefer to work at command line. The Juniper Firewall also supports CLI, you can check the VPN config with the following commands;
If you want you can execute the below commands on CLI to get the “set” commands
show security ike | display set
show security ipsec | display set
show | display set | match <external interface configured in ike>
show | display set | match <st.x>
Above commands will give you the “set” commands for cli.
Related Articles, References, Credits, or External Links
Special thanks to Kalanidhi Tripathi at JTAC for his assistance.
The title of this article can cover a multitude of possible causes, however I recently had a strange problem where a client with a remote site protected by an ASA5505 had a VPN tunnel connected to their main site which had an ASA5510. The tunnel established at phase 1, and phase 2, the main site could talk to the remote site, but the remote site refused to talk back to the main site.
Update 23/04/19: Seen again this time, the ASA at the ‘problem end’ had a static route pointing 10.0.0.0/8 internally, but VPN traffic needed to get to 10.4.0.0/24 at the other end of the VPN tunnel, so traffic was reputed back into the LAN again and dropped.
Update 13/08/14: Seen again, this time from ASA at the problem end, I could ‘ping inside {IP at the remote site}’ and get a response, and the tunnel established. But internal clients could not send traffic over the VPN.
Solution
Usually if you can only “Establish” a tunnel from one side, and it still works, the culprit is normally that PFS has only been specified at one end of the tunnel. On both ends issue a ‘show run crypto map’ command and make sure both ends either use PFS or do not use PFS.
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crypto map outside_map 1 match address outside_1_cryptomap
crypto map outside_map 1 set pfs
crypto map outside_map 1 set peer 123.123.123.123
crypto map outside_map 1 set ikev1 transform-set ESP-3DES-SHA[/box]
However in this case there was a ‘Rogue NAT entry’ on the ASA5505, that looks like a throwback from an OS upgrade.
