vpn connection dropping


Is there a way to keep a VPN connection up instead of dropping when there is no activity?

Let me explain my situation.

For the company where I work for I have set up a VPN connection. It is a connection between the head office and a remote office. I have made the connection with two Sonicwalls. On the head office we have an IP Subnet so the Sonicwall has a public IP have address. The remote office has only one Public IP address. (see the drawing below)

When the connection is set up from the remote office everything works good, but when there is no activity the connection is dropped after a while.

Of course the connection cannot be set up from the head office, since the remote sonicwall has no public ip address.

My problem is that I want to keep the connection up so that it keeps accessable from the Head Office.

Now I am able to do this by letting one of our servers constantly send PING requests to a machine at the remote office. But this feels like a ducktape solution. Is there an other way to keep a VPN connection up for "ever"?


______ ___________ _________ _( )_ DSL |Cisco | |Sonicwall| (_Internet_)--------|2600 Series|_____|PRO 200 |-------------LAN (______) |ADSL_______| |ADSL_____| ^ ^ ^ ^ | | | | | x.x.x.17/30 | | | Public IP address | | | | | | x.x.x.18/30 | | Public IP address | | | | | Lan Gateway


_________ __________ ______ |Sonicwall| |Cisco | DSL _( )_ LAN-------------|SOHO2 |------|800 Series|--------(_Internet_) ^ |_________| |ADSL______| (______) | ^ ^ ^ ^ | | | | | | | | | | | Lan Gateway | | | | | | | | | | | Gateway for | the Sonicwall | | x.x.x.166 Public IP address



Reply to
Bart vd Nieuwenhuizen
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I don't have one of these and have never used one but I thought I'd have a go.

I downloaded the manual from the Sonicwall web site and read the section on the VPN functions. I noticed under the VPN advanced configuration there is an option labelled "Enable Keep Alive". The relevent section reads:- Enable Keep Alive Selecting the Enable Keep Alive check box allows the VPN tunnel to remain active or maintain its current connection by listening for traffic on the network segment between the two connections. Interruption of the signal forces the tunnel to renegotiate the connection.

So there you go. Manuals and documentation are wonderful inventions aren't they?


Reply to

Hi Mike

Thank you for your reply.

I tried to play a bit with the Keep Alive Interval value in the Global VPN Settings before, but that didn't make any difference. I was unable to find the 'Enable Keep Alive' option. Following the manual it could be found under the "Advanced Settings..." buttton in the SA of the VPN connection, but it was not there.

After your reply I tried searching harder: When I changed IPSec Keying Mode from "Manual Key" to "IKE using Preshared Secret", the option "Enable Keep Alive" came availeble.

I never used IKE before, and new options are availeble now that i never used before: Phase DH group, Main Mode, Agressive Mode....

I hope it works out.



Reply to
Bart vd Nieuwenhuizen

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