Re: Debugging what is deleting/recreating /etc/resolv.conf with wrong configuration, on debian stable
On Fri 24 Feb 2023 at 10:19:38 (+0100), davenull@tuxfamily.org wrote:
> > […]
> > vpnc_script has about eight methods available for setting up and
> > reverting resolv.conf. Which is used depends on the presence of
> > a binary, checked in turn from this list:
> >
> > /etc/openwrt_release modify_resolvconf_openwrt
> > /usr/bin/resolvectl modify_resolved_manager
> > /usr/bin/busctl modify_resolved_manager_old
> > /sbin/resolvconf modify_resolvconf_manager
> > /sbin/netconfig modify_resolvconf_suse_netconfig
> > /sbin/modify_resolvconf modify_resolvconf_suse
> > /usr/sbin/unbound-control modify_resolvconf_unbound
> > otherwise modify_resolvconf_generic
> >
> > Perhaps you could check which of those binaries you have.
>
> I have they two resolved_manager binaries, but since systemd-resolvd
> service is disabled and stopped on my system, I highly doubt these are
> used.
> It's more likely modify_resolvconf_generic
>
> However, I didn't notice any vnpc_script malfunction. It does what it
> is expected to do. I'm like 99% sure the problem is dhclient deleting
> and recreating /etc/resolv.conf as it sees fit, multiple times a day,
> and deleting whatever vpnc_script has put in that file.
If that's the case, then unfortunately the vnpc_script gives you no
protection against that happening. All it appears to do, when you
connect, is to write:
#@VPNC_GENERATED@ -- this file is generated by vpnc
# and will be overwritten by vpnc
# as long as the above mark is intact"
at the start of resolv.conf, so that when you disconnect, it can check
if that first string is still there and, if it is, restore the previous
contents of the file.
Meanwhile, anything else might overwrite the file, and if it does,
it's likely that the vnpc_script won't even be able to restore the
previous version of the file when you disconnect.
You'll notice that none of the other functions actually reference
resolv.conf itself, but will store the real file elsewhere, and
publish it through a symlink.
> > > > But how do you manage /etc/resolv.conf with connman. I don't use it,
> >
> > Actually I was interested in what sets up your ordinary networking,
> > the one that uses your ISP, when you're not "at work" …
>
> - ConnMan is used to manually connect to/disconnect from wired, and
> much less often wireless (wifi, bluetooth) networks
> - dhclient is used for DHCP request
They should work with either of the resolvconf packages that Debian
supplies, resolvconf and openresolv. I use the latter, as iwd documents
that it supports it. I know there are people on this list who use connman.
> - My OpenWRT router with DHCP is used as gateway for my subnet,
> answers to DHCP requests
I do much the same, with my router (two, actually) connected to the
ISP's ethernet connector.
> - Then there's is toward my ISP's all-in-one router/modem + TV set top
> box + telephony bullshit (I don't use anything but Interne, but ISP
> enforces their "triple play bullshit so I have to do with that all in
> one device… There's no alternatives for DOCSIS, Since I can't get FTTH
> yet, which my current router doesn't support yet, either way I'm
> dependant on ISP router)
Everything of ours runs from my router, so the ISP's is just a
glorified modem.
Cheers,
David.
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