Hi all,

Dpd and nat keepalive only work on IKE layer, not on the CHILD_SAs that you 
want.

Use auto=route, then bring up the tunnel manually once. Auto=route makes 
strongswan install trap policies for the traffic. That should improve 
reliability.

The newest release brought a new value for start_acrion or use with 
swanctl/vici that enables installing of trap policies and starting of the 
tunnel when the daemon starts.

Kind regards
Noel


Am 17. August 2022 13:35:08 UTC schrieb "Dr. Rolf Jansen" 
<[email protected]>:
>I know what DPD is. Years ago, I used it with the old racoon of the 
>ipsec-tools then with IKEv1, and in racoon.conf I set the dpd_delay and let it 
>after dpd_maxfail call a script with the pahse1_dead argument.
>
>Some times ago, I read the manual ipsec.conf of strongSwan, and I did not 
>realize that „dpdaction = none (default)“ also deactivates DPD and not only 
>the action. Your reply let me read this part again more carefully, and I will 
>try with dpdaction = ....
>
>Now my guess is, that I need to use the action „clear“ on both sides once the 
>mobile connection went down, since it usually does not come back in seconds, 
>most of the times even not in minutes. Then my script would reliably be 
>informed by „ipsec status“ that the connection is down, won’t it?  And it 
>could be brought up again using „ipsec up“ once the G4 router went back 
>online, couldn’t it?
>
>Or may I use the action „hold“? Usually the WAN-IP of the G4 router changes 
>upon down/up cycling. I guess this would confuse the trap policy, which will 
>catch matching traffic, won’t it?   
>
>Thank you very much.
>
>Best regards
>
>Rolf Jansen
>
>> Am 17.08.2022 um 09:56 schrieb Michael Schwartzkopff <[email protected] 
>> <mailto:[email protected]>>:
>> 
>> On 17.08.22 14:50, Dr. Rolf Jansen wrote:
>>> Hello,
>>> 
>>> The IKEv2 tunnels are established between device controllers in a remote 
>>> pilot plant in Spain, which is connected to the internet by a G4 mobile 
>>> router, and an AWS-EC2 instance in Frankfurt. On both sides strongSwan 
>>> v5.9.6 is installed and the OS is FreeBSD 13.0-RELEASE. Both sides are 
>>> behind NAT and receive their local IP via DHCP. For this reason I added on 
>>> both sides static local alias IPs of another reserved block to the 
>>> respective network adapter.
>>> 
>>> Mobile connections are not as stable as wired ones, and quite frequently we 
>>> suffer connection losses. In the pilot plant are two almost identical 
>>> device controllers, and both establish its own IPsec tunnel to said EC2. 
>>> Usually both are down at the same time. This tells me, that origin of the 
>>> connection loss is external, and out of my control. I want to focus on how 
>>> to reliably bring them up again, once the connection was lost.
>> 
>> 
>> That is exactly why Dead-Peer-Detection was included in IKEv2. Did you try 
>> using DPD?
>> 
>> 
>> 
>>> So, I wrote a script which on the remote sites checks the IPsec status of 
>>> the connection, and calls „ipsec up“, in case it is down. The problem is 
>>> now, that „ipsec status“ seems to think it is up even if the connection is 
>>> broken and according to the logs, charon keeps on for hours happily sending 
>>> keep alive messages to the IP of the AWS-EC2 instance which at the same 
>>> time does send keep alives as well to its peers and everybody does it over 
>>> the already broken connections.
>>> 
>>> I experimented with mobike = YES, but it did not make a difference.
>>> 
>>> 
>>> Questions:
>>> 
>>> Is there a more reliable way than „ipsec status“ for knowing whether a 
>>> IPsec tunnel went down?
>>> 
>>> I am not 100 % sure, but it seems that „ipsec up“ does not always bring a 
>>> broken connection up again, should I call something else?
>>> 
>>> The more drastic solution would be to let the remote site ping the internal 
>>> alias address of the EC2 and in case the connection is broken, simply call 
>>> „service strongswan restart“. However, If I need to refrain to this 
>>> measure, for what reason do we have „ipsec status“ and „ipsec up“ then?
>>> 
>>> Best regards
>>> 
>>> Rolf Jansen
>> 
>> 
>> Mit freundlichen Grüßen,
>> 
>> -- 
>> 
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>

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