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Issue #297

isakmp-nat-keep-alive

Added by sam wilson about 6 years ago. Updated almost 6 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
-
Affected version:
5.0.0
Resolution:
Invalid

Description

Hi,

I am trying to change the “isakmp-nat-keep-alive” interval for a VPN connection, but have not been able to do so via the server-side configuration. I measured the keep alive interval to be 20s from a variety of the different clients. Below is an excerpt from a network capture using tcpdump, where 101 is the client and 224 is the server.

23:09:49.712565 IP XX.XX.X.101.41650 > XXX.XXX.X.224.4500: isakmp-nat-keep-alive

23:10:09.713745 IP XX.XX.X.101.41650 > XXX.XXX.X.224.4500: isakmp-nat-keep-alive

23:10:29.712072 IP XX.XX.X.101.41650 > XXX.XXX.X.224.4500: isakmp-nat-keep-alive

I have tried modifying strongswan.conf and changing the “keep_alive” value in charon on the VPN server. Below is an excerpt from my strongswan.conf file.

charon {

install_routes = no
keep_alive = 60
plugins {
attr {
…..

This has not caused the clients to change their keep-alive interval at all. Is this expected, or can the server control the keep-alive interval for a client? The version of strongSwan we are using is 5.0.0 on a Ubuntu 12.04.1 LTS server.

Thank you for your help.

History

#1 Updated by Martin Willi about 6 years ago

  • Status changed from New to Closed
  • Resolution set to Invalid

can the server control the keep-alive interval for a client?

No. NAT keep-alives are not negotiated, therefore you can't change the behavior of the client with a server setting. If your client has such a configuration option, you'll have to change it there.

Regards
Martin

#2 Updated by Andreas Steffen almost 6 years ago

  • Tracker changed from Bug to Issue
  • Assignee set to Martin Willi

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