How To Create Pppoe Connection In Ubuntu

I am using an Ubuntu Server 18.04.2LTS and I want to try to make it as a ppp server in order to study the protocol a bit better via wireshark.

The idea is to use virtualbox and use virtual machines as the following diagram shows:

Virtualbox Setup

Each Vm connected into the Vm using the "Internal networking" configuration over their virtual network card. In othr words I am running the following vms:

          $ VBoxManage list runningvms "Ubuntu PPP Configuration" {55314243-8b75-4a46-a8fa-9e371a63bd7f} <<<< ppp server "ubuntuVM pppclient" {bf57df72-5ae8-406b-b364-4eec324e7cac} <<< pppclient

And each of one have the following network cards:

PPP Server

                      VBoxManage showvminfo 55314243-8b75-4a46-a8fa-9e371a63bd7f | grep NIC NIC 1:           MAC: 080027DACEE9, Attachment: NAT, Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none NIC 1 Settings:  MTU: 0, Socket (send: 64, receive: 64), TCP Window (send:64, receive: 64) NIC 1 Rule(0):   name = Rule 1, protocol = tcp, host ip = , host port = 2022, guest ip = , guest port = 22 NIC 2:           MAC: 0800277B9E7B, Attachment: Internal Network 'intnet', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none

PPP Client

          VBoxManage showvminfo bf57df72-5ae8-406b-b364-4eec324e7cac | grep NIC NIC 1:           MAC: 080027D07155, Attachment: Internal Network 'intnet', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none NIC 2:           disabled

On the PPPoE client machines runnind the Default Desktop variant of Ubuntu 18.04LTS I have installed the "pppoeconf" package and I try to connect over the ppp server using the chap method ( just to study the network connection via wireshark into the host ) but I have this 2 issue:

PPPoE Error

Hence, I wanted to know whether the inteface connecting via PPPoE should have an IP first or no. If no how I can enforce the pppoeconf to use the default interface and connect into the ppp server that I setup?

For the record my ppp server runs and is already working as route -n command shows:

          Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         10.0.2.2        0.0.0.0         UG    100    0        0 enp0s3 10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s8 10.0.2.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s3 10.0.2.2        0.0.0.0         255.255.255.255 UH    100    0        0 enp0s3

The ppp server is manually compiled using this source code over ubuntu 18.04LTS server. On it my /etc/ppp/pppoe-server-options I have setup the following settings for pap authentication (just to see how it works):

          # PPP options for the PPPoE server # LIC: GPL debug plugin /etc/ppp/plugins/rp-pppoe.so require-pap login mtu 500 mru 500 ktune proxyarp lcp-echo-interval 10 lcp-echo-failure 2 nobsdcomp noccp novj noipx

Edit 1

For my ppp client I removed any /etc/ppp/hosts/* file then I used as this answer in order to configure it. Still fails to connect. Do you know how I can debug it?

Furthermore, in the current connection I also have set the only ethernet interface that will use pppoe as well as parent.

Also, my network interfaces onto the client are via (sudo nmcli show command):

          GENERAL.DEVICE:                         enp0s3 GENERAL.TYPE:                           ethernet GENERAL.HWADDR:                         08:00:27:D0:71:55 GENERAL.MTU:                            1500 GENERAL.STATE:                          30 (disconnected) GENERAL.CONNECTION:                     -- GENERAL.CON-PATH:                       -- WIRED-PROPERTIES.CARRIER:               on  GENERAL.DEVICE:                         lo GENERAL.TYPE:                           loopback GENERAL.HWADDR:                         00:00:00:00:00:00 GENERAL.MTU:                            65536 GENERAL.STATE:                          10 (unmanaged) GENERAL.CONNECTION:                     -- GENERAL.CON-PATH:                       -- IP4.ADDRESS[1]:                         127.0.0.1/8 IP4.GATEWAY:                            -- IP6.ADDRESS[1]:                         ::1/128 IP6.GATEWAY:                            -- IP6.ROUTE[1]:                           dst = ::1/128, nh = ::, mt = 256