IPSEC configuration HUGE doubts and problems. Please, experts help is needed.

Hi friends,

I'm getting very worried because a few days ago I've been posting the same doubt and editing the text to make it clearer, but I have no response from the Experts Exchange or any other Expert (there's a lot of good ones here)... I've been a Experts Exchange subscriber for over 5 years now... and never before have I been without the help of the experts ... I do not understand why it was left in oblivion.

Well... lets get to the point...

Please, I need to connect a strongswan VPN (my side) with another VPN software (other side) but the admin from "the other side doesn't provides enough info... so I'm trying to figure out and troubleshoot this with trial and error... already for many days and a lot of migraines...

They (the other side) provide me a PSK (OK)... already configured in ipsec.secrets and they also gave me the following instructions:  

1st Phase (IKE V2)                                          
DH 2 = 1024 bits                                           
Lifetime = 1440m                                           
2nd Phase (ESP)                                          
PFS - DH 2 - 1024 bits                                          
Lifetime = 3600s

My question is (please): how do I configure this specific connection? especially the parameters ike and esp; anything else is needed in the configuration example below?

conn myside-otherside

In time... My participation here in the Experts Exchange is not so good because, mainly, of the language barrier and also because the overwork (which sucks up to those milliseconds I'd like to save per day) that everyone here knows... :)

Finally... Please... If I'm doing something wrong that is causing this lack of interest in my questions, I apologize in advance and ask you guys to clarify me how I can overcome / correct the situation.

Best Regards
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ajohnson30Network ManagerCommented:
Typically the "esp" and "ike" parameters on a vpn tunnel are the encryption type descriptors supported.  It looks like on StrongSwan this is no exception.  It appears you need something like


Open in new window

Take a look at https://www.digitalocean.com/community/tutorials/how-to-set-up-an-ikev2-vpn-server-with-strongswan-on-ubuntu-16-04

If I had to guess, I'd say you weren't getting replies because StrongSwan is such a one-off vpn.  Most people are using a Cisco, SonicWall,  Juniper, or even OpenVPN compatible.

Hope this helps,
FabioConsultantAuthor Commented:
Hi ajohnson30,

How are you?

Thanks INDEED for your reply.

Today, after a lot of asking, I finally got some info about the "other side"... They're using a Checkpoint to their end of VPN.

About IKE and ESP, my doubt is what algorithms should I configure in ike and esp parameters using that info they gave to me? I think that I'm using the right ones:

But I'm getting this error when I start the connection with the command "ipsec up myside-otherside":

initiating IKE_SA myside-otherside[3] to
generating IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) ]
sending packet: from[500] to[500] (540 bytes)
received packet: from[500] to[500] (384 bytes)
authentication of '' (myself) with pre-shared key
establishing CHILD_SA myside-otherside
generating IKE_AUTH request 1 [ IDi N(INIT_CONTACT) IDr AUTH SA TSi TSr N(EAP_ONLY) ]
sending packet: from[500] to[500] (352 bytes)
received packet: from[500] to[500] (80 bytes)
parsed IKE_AUTH response 1 [ N(TS_UNACCEPT) ]
IDr payload missing
generating INFORMATIONAL request 2 [ N(AUTH_FAILED) ]
sending packet: from[500] to[500] (80 bytes)
establishing connection 'myside-otherside' failed

Any clues??

Once again, thank you INDEED for your help and for your reply!

Best Regards
ajohnson30Network ManagerCommented:
Your problem looks very similar to this one.  Perhaps it helps?
Basically in message #3 he is saying he had some ip addresses swapped around in the config.  Once that was corrected, the tunnel got past the authentication
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FabioConsultantAuthor Commented:
Hi again friend,

I can't thank you enough for your attention.

I was googling the "IDr payload missing" and got just a few answers... but all answers regarding IKEv2...

As the people on the "otherside" mentioned that IKEv1 could be used, I changed to IKEv1 and also changed rightid and leftid to "%any"... I think that the IKEv2 configuration on the "otherside" is incorrect or missing something (probably rightid and leftid fields).

The esp and ike parameters are configured this way:


Unfortunately "they" probably will not (never) tell me what was wrong (They probably will tell that my configuration was wrong... LOL), but if (by some miracle) they report the error, I'll post it here.

Once again thank you indeed for your help and attention.

Best Regards

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ajohnson30Network ManagerCommented:
The guide I saw did have an exclamation mark "!" on the end of the encryption specifier "modp1024!".  I don't know if that matters
FabioConsultantAuthor Commented:
The information I had was incomplete, and the efforts and attention of ajohnson30 helped me to confirm that the error was not in my settings and helped me find an alternative and a solution.
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