I had two problems with ppp while trying to make the idle timeout only count outbound packets. The first is that when I run pppd with an 'outbound' filter I get the error message: pppd: error in active-filter expression: inbound/outbound not supported on linktype 0 This makes it seem like it is checking the link type before the link is set up and so it 'outbound' isn't a valid filter rule because it is only valid for ppp and slip links. The second problem was that I was using the options tab of the network configuration tool to add the option (as opposed to editing the appropiate config file directly) and I found that when I deleted the option (so that I could activate my ppp link) it didn't remove the option from the config file. I had to go in and manually remove it from the config file. There is probably a way to make another test that will work, but since my ip address is dynamic it isn't obvious. Without an active-filter the idle timeout feature is useless since my system gets probed much more frequently than what I want to use for a timeout.
