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Xander
New Contributor II

Site to site VPN Fortigate 5.4 and Cisco- NO-PROPOSAL-CHOSEN

Hello,

 

In our company we have Fortigate 60D (v5.4.1) and I'm trying to setup the VPN with Cisco router. Cisco router is owned by other company and I do not have access to it. Phase 1 seems to work as expected ([...] - text cut for better visibility):

ike 0:phase-1-int:193473: negotiation result
ike 0:phase-1-int:193473: proposal id = 1:
ike 0:phase-1-int:193473: protocol id = ISAKMP:
ike 0:phase-1-int:193473: trans_id = KEY_IKE.
ike 0:phase-1-int:193473: encapsulation = IKE/none
ike 0:phase-1-int:193473: type=OAKLEY_ENCRYPT_ALG, val=AES_CBC, key-len=256
ike 0:phase-1-int:193473: type=OAKLEY_HASH_ALG, val=SHA2_512.
ike 0:phase-1-int:193473: type=AUTH_METHOD, val=PRESHARED_KEY.
ike 0:phase-1-int:193473: type=OAKLEY_GROUP, val=ECP384.
ike 0:phase-1-int:193473: ISAKMP SA lifetime=28800
[...]
ike 0:phase-1-int:193473: VID CISCO-UNITY [...]
ike 0:phase-1-int:193473: peer supports UNITY
[...]
ike 0:phase-1-int:193473: DPD negotiated
ike 0:phase-1-int:193473: NAT not detected
ike 0:phase-1-int:193473: PSK authentication succeeded
ike 0:phase-1-int:193473: authentication OK
ike 0:phase-1-int:193473: established IKE SA [...]

 

But then I get the error as follows

 

ike 0:phase-1-int:193473: notify msg received: NO-PROPOSAL-CHOSEN
ike 0:phase-1-int:193473:phase-2-int:4954165: IPsec SPI d888eef3 match
ike 0:phase-1-int:193473:phase-2-int:4954165: delete phase2 SPI d888eef

I've asked the Cisco admin for config details and after comparison we have

Phase_1

the same Diffie-Hellman group the same proposal (aes256 - sha512) the same keylife (in seconds) Phase_2

The same Diffie-Hellman group ("dhgrp" parameter on Fortigate and "pfs" parameter on Cisco)

The same keylife (in kilobytes)

Proposals are:

Fortigate

set proposal aes256-sha512
Cisco

set transform-set esp-aes_256_esp-sha512-hmac
crypto ipsec transform-set esp-aes_256_esp-sha512-hmac esp-aes 256 esp-sha512-hmac
Can anyone tell me what could be wrong?

I'm not network specialist and I don't know even what to ask the mentioned Cisco admin.

Any help appreciated.

 

Best regards

Alex

1 Solution
Xander
New Contributor II

Hi Kadkwai

I've solved the problem after a lot of troubleshooting together with very skilled friend of mine.

I had to solve 2 issues:

1 - We had to NAT the traffic before it went into the tunnel (office lan -> NAT -> VPN tunnel)

2 - Than we received information that on the Cisco side the phase2 interface is configured to match specified IP addresses that are on the access list only (we specified the addresses before so we knew them all)

match address ac-list

My final configs are as follows Phase1

edit "vpn-p1"
set interface "wan1"
set keylife 28800
set proposal aes256-sha512
set dhgrp 20
set mesh-selector-type subnet <- this allows to provide several addresses "remote-networks-on-ac-list", see phase2 below
set remote-gw [1.2.3.4]
set psksecret ENC secret
next

Phase 2

edit "vpn-p2"
set phase1name "vpn-p1"
set proposal aes256-sha512
set dhgrp 20
set auto-negotiate enable
set keylife-type kbs
set src-addr-type name <- we need that to NAT our traffic
set dst-addr-type name <- we need that to mach the IP put on cisco access list
set keylifekbs 512000
set src-name "our-nat-ip" <- we need that to NAT our traffic
set dst-name "remote-networks-on-ac-list" <- we need that to mach the IP put on cisco access list
next

src-name and dst-name you can define in

config firewall address

e.g.

edit "our-nat-ip"
set subnet 3.4.5.6 255.255.255.255
next
edit "network-1"
set subnet 192.168.1.0 255.255.255.0
next
edit "network-2"
set subnet 192.168.2.0 255.255.255.0
next

and

config firewall addrgrp

e.g.

edit "remote-networks-on-ac-list"
set member "network-1" "network-2"
set allow-routing enable
next

Hope this helps!

BR

Alex

View solution in original post

10 REPLIES 10
moby
Contributor

Hi Alex,

 

The above Cisco configuration only show the phase 2 (IPSEC) configuration. You should also check the phase 1 configuration for the Cisco router which would been shown in the ISAKMP policy in the configuration of the Cisco router. Also is dead peer detection enabled/disabled at each end?

 

Moby

MikePruett
Valued Contributor

Making sure things match 100% is my go to. Things like NAT-T, timers being off, encryption / authentication means being incorrect etc.

 

Remember, the FortiGate will follow RFC perfectly. So if the Cisco side doesn't match 100% it will kill it. For instance, Palo Alto firewalls you can chose the timer as a period of days etc. Even if the FortiGate has the correct number of seconds in the timer that matches said day period of the Palo the connection will fail.

 

 

Mike Pruett Fortinet GURU | Fortinet Training Videos
Xander
New Contributor II

The below config is all that I've got from the Cisco admin.

The parts marked [in square braces] were changed by me to anonymize some entries

 

crypto isakmp policy ###
encr aes 256
hash sha512
authentication pre-share
group 20
lifetime 28800
crypto map [name] [##] ipsec-isakmp
set peer [1.2.3.4]
set security-association lifetime kilobytes 512000
set transform-set esp-aes_256_esp-sha512-hmac
set pfs group20
match address [ac-name]
reverse-route

crypto ipsec transform-set esp-aes_256_esp-sha512-hmac esp-aes 256 esp-sha512-hmac

 

Regarding the DPD: I don't know if it is turned on on Cisco side but I can see something like this in the logs:

 

ike 0:phase-1-int:193469: sent IKE msg (R-U-THERE): 1.2.3.4:500->5.6.7.8:500, len=140, id=[...]
ike 0:phase-1-int:193469: notify msg received: R-U-THERE-ACK

 

Does indicates that DPD works fine or not necessarily?

 

My config is as follows

 

phase-1-int

config vpn ipsec phase1-interface
edit "phase-1-int"
set interface "wan1"
set local-gw [1.2.3.4]
set keylife 28800
set proposal aes256-sha512
set dpd on-idle
set dhgrp 20
set remote-gw [5.6.7.8]
set psksecret ENC (encrypted)
set dpd-retryinterval 10
next
end

 

phase-2-int

config vpn ipsec phase2-interface
edit "phase-2-int"
set phase1name "phase-1-int"
set proposal aes256-sha512
set dhgrp 20
set auto-negotiate enable
set keylife-type kbs
set src-addr-type ip
set keylifekbs 512000
set src-start-ip [9.10.11.12]
next
end

 

neonbit
Valued Contributor

Config looks ok except for the following on the Cisco side:

 

set security-association lifetime kilobytes 512000

 

Would it be possible for them to change this to:

 

set security-association lifetime seconds 512000

 

Since the FGTs keylife is in seconds.

ede_pfau

nope, both firewalls use KBs in phase2 as configured.

FortiOS supports both, default is seconds.

Ede Kernel panic: Aiee, killing interrupt handler!
Ede Kernel panic: Aiee, killing interrupt handler!
neonbit
Valued Contributor

ops sorry didn't see he changed the keylife type, pls diregard!

 

 

Xander
New Contributor II

Hi All

Thanks for all the replies and hints. Problem still exists but I'll send the suggestions to the mentioned admin and wait for his reply. I'll post the solution here if I found one.

BR

Alex

kadkwai
New Contributor

Hi Alex,

 

I'm having the same issue! Were you able to resolve this problem ? 

 

Thank you,

Xander
New Contributor II

Hi Kadkwai

I've solved the problem after a lot of troubleshooting together with very skilled friend of mine.

I had to solve 2 issues:

1 - We had to NAT the traffic before it went into the tunnel (office lan -> NAT -> VPN tunnel)

2 - Than we received information that on the Cisco side the phase2 interface is configured to match specified IP addresses that are on the access list only (we specified the addresses before so we knew them all)

match address ac-list

My final configs are as follows Phase1

edit "vpn-p1"
set interface "wan1"
set keylife 28800
set proposal aes256-sha512
set dhgrp 20
set mesh-selector-type subnet <- this allows to provide several addresses "remote-networks-on-ac-list", see phase2 below
set remote-gw [1.2.3.4]
set psksecret ENC secret
next

Phase 2

edit "vpn-p2"
set phase1name "vpn-p1"
set proposal aes256-sha512
set dhgrp 20
set auto-negotiate enable
set keylife-type kbs
set src-addr-type name <- we need that to NAT our traffic
set dst-addr-type name <- we need that to mach the IP put on cisco access list
set keylifekbs 512000
set src-name "our-nat-ip" <- we need that to NAT our traffic
set dst-name "remote-networks-on-ac-list" <- we need that to mach the IP put on cisco access list
next

src-name and dst-name you can define in

config firewall address

e.g.

edit "our-nat-ip"
set subnet 3.4.5.6 255.255.255.255
next
edit "network-1"
set subnet 192.168.1.0 255.255.255.0
next
edit "network-2"
set subnet 192.168.2.0 255.255.255.0
next

and

config firewall addrgrp

e.g.

edit "remote-networks-on-ac-list"
set member "network-1" "network-2"
set allow-routing enable
next

Hope this helps!

BR

Alex

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