Understanding how keepalives work

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Understanding how keepalives work

Post by boomchke » Fri Mar 31, 2017 3:05 am

Hi All. I'm trying to get a better understanding of how the keepalive configuration works. In my case, the server configuration has a keepalive of 10 30 configured. My understanding is that this means that the server will send a 'ping' (not ICMP) to the client every 10 seconds to make sure it's alive. If it doesnt get any response from the client after 30 seconds it will disconnect. Now here's where Im a little confused...

I had thought this was just a server side configuration. That is the server would ping based on the this setting and then the client would reply. Sounds like the setting needs to be on both ends and that the keepalive settings takes care of 'pushing' this setting to the client. It also sounds like that if one side (either the remote or the server, Im using a server with tunnelblick clients) doesnt hear anything in 30 seconds it does a ping-restart. So does that imply that if this setting doesnt get pushed to the client, or if the client doesnt honor it, that if there is no VPN activity for 30 seconds, despite the server sending pings and the client receiving them, that the client will perform a ping restart action?

Lastly - the man page make it seem like if the server times out a keepalive it just kills the client session whereas the client will perform a ping-restart (reconnect). Is that true?

Thanks for any help. Im trying to sort out some weird issues where clients appear to for no reason be going into ping-restart. Can't sort out why if the keepalives are working so Im trying to sort that out.

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Re: Understanding how keepalives work

Post by TinCanTech » Fri Mar 31, 2017 11:02 am

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