Check Point DPD (Dead Peer Detection) - Questions

[Marcel_Gramalla]

Hi all,

I have two questions regarding the Dead Peer Detection between our Check Point Cluster and other existing VPN connections to non-Check Point Gateways.

1. Does enabling DPD (Responder Mode) has any impact on existing VPN connections? Can I enable it "on-the-fly" without having any disconnects to the VPN? I haven't found an answer on that yet.

2. If I change a VPN community with non-Check Point Gateways to "Permanent Tunnels" in order to active DPD with GuiDBedit does this have any impact on existing connections?

Thanks in advance for any help

[Jerry]

quickly though:

Ad.1 - it will re-estab SA/SPI indeed
Ad.2. - it will re-estab the tunnel

ps. any changes to the proxy-id or any crypt.conf params will re-key and re-estab SA/SPI

[Marcel_Gramalla]

Thanks for the quick reply. That means that we have to announce it so that if there is any issue our partners know about it.

[Jerry]

it will in 100% impact/affect an existing tunnel(s) so yes, that should be announced and planed for so called "maintenance window" 🙂

cheers

[Ravindra_Katrag]

Is there any way to check if DPD is enabled?

[Nick_Doropoulos · Accepted solution]

Yes, there is. You can check with the GuiDBedit tool under Network Objects >> network_objects:

I hope this helps.

[Ravindra_Katrag]

Thank you

[Nick_Doropoulos]

My pleasure!

[nagaraja_cs]

Can we achieve VPN redundancy with 3rd party Gateways by enabling DPD(In R80.10 or R80.20) ?

[Ted_Serreyn]

Can we enable Dead Peer detection on the third party devices only?  Or do we have to enable it on the checkpoint gateways also? My understanding is if enabled on the checkpoint gateways it affects all other VPNs?

[Timothy_Hall]

You can set DPD per remote gateway via the tunnel_keepalive_method variable in GUIDBedit as described in this lengthy thread, you don't have to change this value for your Check Point gateway:

https://community.checkpoint.com/t5/Next-Generation-Firewall/Enable-DPD-on-R80-20/m-p/32605

Starting in R81 tunnel_keepalive_method will be set to DPD by default on all Interoperable Device object types.

[Gavin]

Do you know how to capture DPD packets in any way? I could see tunnel test in the logs, but seem to be missing how to spot DPD packets. I can't see them in TCPDUMP as they are encrypted. I would really appreciate some guidance on this. I am working on an AWS VPN issue where I think the tunnels are being shut down regularly and I would like to spot what is going on. I have a TAC case open but every time I ask the question they seem to swerve around it.

[PhoneBoy]

fw monitor should show the packets as they are encrypted/decrypted.

[Hussien_Wahab]

AWS sends "isakmp-nat-keep-alive" packets that are outside the DPD tunnel health monitoring, please see the packets in red (the ones in blue are for the actual DPD that keeps the tunnel status up and alive)