Re: restarting pppd automatically
Hi Tomas
On 28/12/2020 09:28, tomas@tuxteam.de wrote:
> On Sun, Dec 27, 2020 at 11:56:21PM +0000, Graham Seaman wrote:
>> I'm having problems with pppd and an intermittent phone line
>
> Wow. Memories fading :-)
>
> OK, my recollection on inittab is a bit dusty, and I have little
> experience with systemd (trying to keep it that way). But I'll
> try a shot at it.
>
> The idea of inittab was to keep an eye on some processes: when
> they died, they were restarted ("respawn", in inittab parlance).
>
> This was init's job (thus inittab). Its main customers were
> the login processes. At their other end were serial lines
> attached to terminals (ah, vt220...). A user logged in at
> one of those things, the login handed off to a shell or something,
> when the user logged off the shell terminated, the calling
> login terminated and... respawn.
>
> Other things followed, typically daemons and... pppd.
>
> Then came SysV: daemons had to take care of themselves, PID
> files grew like mushrooms all over the place. It was bad
> times. The inittab was still there, mind you, but it was only
> tending to the Linux consoles (tradition perhaps :-) and to
> non-existing serial terminals. My system still has one,
> perhaps yours too.
>
> Now with systemd, we've turned full circle (unfortunately, with
> seventeen layers of complexity stacked in-between). In theory,
> systemd /should/ be able to do exactly what init used to do
> back then.
>
> Searching for "inittab systemd" via our favourite search engine
> (no, not that one with the big G) yields a couple of good
> hits. In [1] there's an example on how to translate an inittab
> entry into a systemd unit file.. In [2] you can see where the
> systemd unit files for your serial console live under Debian,
> perhaps there /is/ already something near that for pppd?
>
> Assuming you are on Buster... the list of files for package
> ppp (where pppd lives) is here [3]. No, no unit for respawn,
> alas. Only one to kick systemd's DNS service on connect and
> disconnect events (/lib/systemd/system/pppd-dns.service).
>
> Seems like you'll have to fashion one after some /lib/systemd/...tty.service.
> Perhaps there's someone around here who has done that to
> help you out. Tip: don't put it in /lib/systemd/... This
> place os for your distro. Put it somewhere in /etc/systemd/...
> that's for you, the admin. I can't provide details -- no
> experience with that.
>
> I'd try to file a bug against ppp: they should be providing
> a systemd unit file.
>
> Cheers
> - t
>
>
> [1] https://forums.opensuse.org/showthread.php/475468-In-search-for-a-inittab-entry-replacement-for-systemd#7
> [2] https://wiki.debian.org/systemd#line-288
> [3] https://packages.debian.org/buster/amd64/ppp/filelist
Thanks for the explanation. I'm filing it away and if Tixy's simple
configuration solution has unexpected side-effects I'll have a go at this.
Cheers
Graham
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