The built-in Cisco VPN client introduced in Mac OS X 10.6 Snow Leopard has the habit of disconnecting itself when re-keying should be performed but fails after about 48 minutes up to one hour. This timeout issue has been fixed in Mac OS X 10.6.4.

In versions of Mac OS X 10.6.0 up to 10.6.3, the problem can be worked around by increasing the re-keying period to e.g. 1 week.

Note

The update to Snow Leopard 10.6.4 fixes the issue of the VPN disconnecting after 48 minutes many people have observed in 10.6.0–10.6.3. Therefore, there is no need to change the configuration of racoon anymore.

In order to revert your configuration to the stock one, remove the last line from /etc/racoon.conf, so that the last line is again

include "/var/run/racoon/*.conf" ;

Please let me know in the comments if you still observe disconnections with 10.6.4.

Note that this workaround severely decreases the security of your VPN connection as attackers now have up to 1 week to attack the phase 1 key.

I have no clue where Apple stores the configuration template for racoon, but I have found the following workaround.

  1. Create directory “/etc/racoon/remote” as root:
sudo mkdir /etc/racoon/remote

  1. Open a VPN connection to your Cisco VPN concentrator. This should result in the creation of a config file located at /var/run/racoon/10.1.1.1.conf, where 10.1.1.1 is the IP address of the VPN concentrator.

  2. Move this dynamically created file to /etc/racoon/remote before we change its contents:

sudo mv /var/run/racoon/*.conf /etc/racoon/remote
  1. Now we edit the file, replacing all lines
lifetime time 3600 sec;
by
lifetime time 168 hours;
This is achieved by the following `sed` command:
sudo sed -i.bak 's/lifetime time 3600 sec/lifetime time 168 hours/' /etc/racoon/remote/*.conf
  1. To make racoon read our converted file, insert a line
include "/etc/racoon/remote/*.conf" ;
right before the last line of `/etc/racoon.conf`. The last two lines should now be
include "/etc/racoon/remote/*.conf" ;
include "/var/run/racoon/*.conf" ;
This is achieved by executing the following patch command:
sudo patch /etc/racoon/racoon.conf <<EOF
--- /etc/racoon.orig/racoon.conf	2009-06-23 09:09:08.000000000 +0200
+++ /etc/racoon/racoon.conf	2009-12-11 13:52:11.000000000 +0100
@@ -135,4 +135,5 @@
 # by including all files matching /var/run/racoon/*.conf
 # This line should be added at the end of the racoon.conf file
 # so that settings such as timer values will be appropriately applied.
+include "/etc/racoon/remote/*.conf" ;
 include "/var/run/racoon/*.conf" ;
EOF
  1. Restart racoon:
sudo launchctl stop com.apple.racoon
sudo launchctl start com.apple.racoon

That’s it. If this did not do the trick, try restarting your machine.

To summarize, here are all the commands to be executed:

	sudo mkdir /etc/racoon/remote
    sudo mv /var/run/racoon/*.conf /etc/racoon/remote
	sudo sed -i.bak 's/lifetime time 3600 sec/lifetime time 168 hours/' /etc/racoon/remote/*.conf
	sudo patch /etc/racoon/racoon.conf <<EOF
	--- /etc/racoon.orig/racoon.conf	2009-06-23 09:09:08.000000000 +0200
	+++ /etc/racoon/racoon.conf	2009-12-11 13:52:11.000000000 +0100
	@@ -135,4 +135,5 @@
	 # by including all files matching /var/run/racoon/*.conf
	 # This line should be added at the end of the racoon.conf file
	 # so that settings such as timer values will be appropriately applied.
	+include "/etc/racoon/remote/*.conf" ;
	 include "/var/run/racoon/*.conf" ;
	EOF
	sudo launchctl stop com.apple.racoon
	sudo launchctl start com.apple.racoon