Web lists-archives.com

Re: Accessing a host with variable IP addresses / connection types





Le 17/04/2019 à 14:15, Celejar a écrit :
On Wed, 17 Apr 2019 08:37:20 +0200
Kevin DAGNEAUX <kevin.dagneaux@xxxxxxxxxxxx> wrote:

Hi,

I've been bedeviled by this question for a while, but have been unable
to figure out a clean, non-hackish solution. It may be an XY problem ...

I have a system (laptop, running Debian) that is sometimes connected
directly to my LAN, and sometimes connected via VPN (wireguard, to the
local router, running OpenWrt). The LAN is 192.168.0.0/24, with the
laptop having a fixed, static address in that range (although I'm
certainly open to using DHCP, possibly with a fixed address
reservation). The VPN is 10.0.0.0/24, with the laptop getting a fixed,
static address in that range (and wireguard apparently doesn't work
with dhcp).

I currently have an entry in /etc/hosts on the various LAN hosts
assigning a hostname to the laptop's fixed local address, and the LAN
hosts can access the laptop via that hostname. [I could alternatively
use dnsmasq, which is running on the router regardless.] This obviously
doesn't work when the laptop is connected via VPN. [The laptop can
access the LAN hosts fine via their hostnames, so I seem to have the
routing correctly configured on the laptop and the router.]

What I seem to want (but maybe XY?) is some way to adjust the host
files (or dnsmasq's information) so that the hostname will resolve to
the LAN address when the laptop is connected to the LAN, and the VPN
address when it's connected via VPN. If everything was using DHCP, this
would be straightforward enough, but as I said, the VPN apparently
needs to be configured statically, and not via DHCP. I could obviously
use some custom script (using, say, ageas, to modify host files) but
this seems hackish. What is a standard, 'correct' way to do this, or
more generally, to enable the LAN hosts to access the laptop
seamlessly regardless of its IP address and connection type?

Celejar

Hi,

A possible solution is to use a bridged VPN, in this case, your laptop
will always have the same IP.
Thanks. I can't seem to find much information about this - can you
elaborate, or point me to a link? [I'm not a networking expert.]

Currently, my LAN is 192.168.0.0/24, which is also the addressing
scheme of some of the networks out of my control that I'm setting up a
VPN link from. I deliberately used 10.0.0.0/24 for the VPN to avoid
address collisions with these other networks. It did occur to me to
consider using a different address space, for the VPN or perhaps for the
whole home LAN, but I'd rather not take that step just to solve what
seems a relatively simple problem unless absolutely necessary

Celejar

Celjar,

You can find some explaination at https://openvpn.net/community-resources/ethernet-bridging/

Using common network adressing will often give address collisions when using VPN (routed or bridged VPN), like if on your home network and remote network you have 2 machin with same IP, one of them will not be reachable (depending of your routing table).

Kevin

begin:vcard
fn:Kevin DAGNEAUX
n:DAGNEAUX;Kevin
org:Fiitelcom
adr;quoted-printable:;;12 rue du Pr=C3=A9 Drou=C3=A9;Chavelot;;88150;France
email;internet:kevin.dagneaux@xxxxxxxxxxxx
title:Informaticien
tel;work:03 29 36 88 85
x-mozilla-html:TRUE
url:https://www.fiitelcom.fr
version:2.1
end:vcard