[stunnel-users] Stunnel 5.44 server side 'exec = pppd' runs second child 'pppd' process after reconnection. Bug?

[Florian Lohoff]

On Tue, May 14, 2019 at 11:30:29AM -0700, Eric Eberhard wrote:
> That is not a bad idea.  I'd wrap it in a C program so I could check
> if the pppd is alive and not a zombie.  BUT -- it begs the question,
> why only ONE?  Every time this happens the process ID would change.
> Is it serialization or?  I am thinking there is something we don't
> know ... I have offered Martin some help ...

pppd is a pretty solid piece of software. Never seen it hang as a
zombie.

Only one because for a given static ip address you can only use
it once - Given that your static ip address is bound to a specific
peer name you should kill all other pppd's for that peer. 

Abusing either "linkname" to get pppd to write a pid file with
a known pid file or finding the right pid file with
the route which points to the interface which is part of
the default pid file name.

So we can find the "other" pppd still running because it did
not yet detect the tcp sessions with stunnel beeing disconnected.

This is what the lcp echo feature is for. pppd will send echo frames
in the Link Control Protocol (LCP) on a regular basis if there
is no incoming traffic. Missing the echo reply will lead pppd
to terminate and free up the interface and through that the
static ip address assigned to that peer.

Flo
-- 
Florian Lohoff                                                 f at zz.de
        UTF-8 Test: The 🐈 ran after a 🐁, but the 🐁 ran away
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