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Re: Forcing dhclient to not ignore tun0 interface when it's available



Hello

On 2023-03-07 05:01, David Wright wrote:
On Mon 06 Mar 2023 at 13:17:23 (+0100), davenull@tuxfamily.org wrote:
On 2023-03-03 06:22, Max Nikulin wrote:
> On 03/03/2023 10:08, Tim Woodall wrote:
> > New to this thread, so might be totally off-piste but openvpn
> > has hooks
> > to run scripts like this:
> ...
> > This is server side but the route-up/pre-down work client side too.

Since it's workplace's VPN, which I don't have access to, I can't do
anything which requires server-side access.
Plus, it's a Cisco VPN. I don't anything aout cisco stuff. I'm more
familiar with openVPN

> >
> > Presumably you can do something here to renew dhcp leases or restore
> > resolv.conf.
>
> Perhaps the opposite. dhclient running for enp2s0f0 should detect that
> VPN is active and to avoid overwriting DNS settings that direct
> requests to tun0.

Yes, indeed. I want dhclient to NOT overwrite /etc/resolv.conf when
VPN is active. OR to use tun05 when it tries to renew the lease

One person at work suggested to use resolvectl/resolvconf but after
looking at it, I noticed it requires using sytemd-resolved, which
I don't use.

  Package: resolvconf
  Depends: lsb-base (>= 4.1+Debian3), debconf (>= 0.5) | debconf-2.0

AIUI systemd-resolved is a replacement for openresolv, and it's
systemd-networkd that can work alongside openresolv.

As an alternative, there is openresolv, which seems work without
resolved. But I failed to find any document on how to useit with
openconnect.

Yes, no dependencies.

Openconnect will supply openresolv with the information it needs
when the vpnc-script that we discussed earlier runs. It's at the
function "modify_resolvconf_manager", around line 690.

The official website config page only gives parameters for some
well-known local resolvers, including unbound.

It also covers Bind, named (a part of bind), and dnsmasq
(mentioned in that script). All these are in Debian.

Yes. but I don't need any of these, or other local (at in localhost) resolver.
So that official page isn't helpful in my case.


If anyone has a good documention on how to configure openresolv
correctly to use it with openconnect.

I see that the openresolv wiki at Arch has a section on openconnect.
Obviously you may need to "bend" their pages when consulting them
for Debian.


Will check that out. I just realized "resolvconf" command in the script given in openconnect's Arch wiki page is not necessarily resolvclt and might as well refer to openconnect. When I searched for keybould with both openresolv and openconnect,
all I've found was a (still open) 3 years issue on openconnect't gitlab.

I'll give it a try and see what's to adjust for debian, once workload allows that.

Thing is : years ago I used to use OpenVPN on debian on another
computer, the DHCP client was also dhclient
but I didn't to do any extra configuration, it just worked… The only
differences was an older debian version,
as the stable batk them was like Debian 7 or 8, and I was using wicd
instead. So the network stuff probably changed since then

Therefore I have no damn idea on how to configure stuff like openresolv.

Cheers,
David.


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