Establish hook not always called on connect about fastd HOT 4 OPEN

The on-establish hook is not run when renewing an existing connection; this is expected. Unfortunately is it sometimes necessary to tear down and recreate L2TP offload interfaces even for a renewal, as some settings can't be changed for existing L2TP interfaces.

For interface setup, use on-up, which is called each time an interface is created (and for each peer in TUN and Multi-TAP mode).

Note that on-up is currently not passed all environment variables that on-establish gets (in particular, no IP address and port information). This is unlikely to be an issue in practice, as this information is fairly useless with on-establish as well for anything but logging purposes, as addresses and ports may change without on-establish being called again...

from fastd.

What would be the appropriate hook to clean up after disconnect/timeout? Thinking of setting link down, nomaster and removing the link, or is that entirely pointless?

The documentation on when these hooks are called is slightly unintuitive.

from fastd.

Hmm yes, I think some of the documentation predates the multi-interface modes of fastd and could use some updates and clarification...

The rules are:

• on-up is run just after the interface has been created, on-down just before the interface is removed
• In TUN and Multi-TAP mode, on-establish is normally run after on-up, and on-disestablish is run before on-down. However, additional on-down+on-up pairs can happen on renewal without further on-establish/on-disestablish when L2TP offloading is enabled - either because a new L2TP interface needs to be created to change tunnel configuration, or when switching between null@l2tp and another method.
• Each on-up call is eventually matched by an on-down and each on-establish by an on-disestablish
• With persist interface no, a peer interface is removed as soon as its connection times out (or is disestablished for another reason)

on-down is usually the right place for cleanup, if there is anything that isn't cleaned up simply by the interface disappearing.

from fastd.

Maybe it would be a good idea to deprecate on-establish/on-disestablish in TUN and Multi-TAP modes to reduce confusion, and possibly extend peer-specific on-up/on-down to include the same environment as on-establish/on-disestablish currently do.

Edit: This only makes sense when persist interface no is also set

from fastd.