Fresh Debian 10 with pihole networking.service : Failed to start Raise network interfaces

Hi guys,

i have something here I tried to troubleshoot for some hours but I am not getting anywhere. I installed pihole before on Debian, but never had this one.

Distributor ID: Debian
Description: Debian GNU/Linux 10 (buster)
Release: 10
Codename: buster

4.19.0 #1 SMP Tue Jun 9 12:58:54 MSK 2020 x86_64 GNU/Linux

I tried to check why networking is not starting anymore after using the pihole install script from the ROOT account:
(curl -sSL https://install.pi-hole.net | bash)

# sudo grep venet0 -R /etc/

Auto generated venet0 interfaces
auto venet0
iface venet0 inet static
up route add default dev venet0
iface venet0 inet6 static
up ip -6 r a default dev venet0
up ip addr add xxxxxxx/64 dev venet0
auto venet0:0
iface venet0:0 inet static
/etc/dnsmasq.d/01-pihole.conf:interface=venet0
/etc/dhcpcd.conf:interface venet0
/etc/pihole/setupVars.conf:PIHOLE_INTERFACE=venet0
/etc/pihole/setupVars.conf.update.bak:PIHOLE_INTERFACE=venet0
Binary file /etc/pihole/pihole-FTL.db matches

After installing pihole with the pihole install script, the networking, lighttpd and other related networking services in the red lines stopped working. I tried to check out forums, but I am out of idea's
This is a VPS machine. Before running the pihole script all the red lined services in the picture were running ok. I chose comodo DNS during setup .
I will send the log of install pihole along:

# cat /etc/pihole/install.log                     

 [✓] Installing scripts from /etc/.pihole

  [i] Installing configs from /etc/.pihole...
  [i] Existing dnsmasq.conf found... it is not a Pi-hole file, leaving alone!
  [✓] Copying 01-pihole.conf to /etc/dnsmasq.d/01-pihole.conf

  [i] Installing blocking page...
  [✓] Creating directory for blocking page, and copying files
  [i] Backing up index.lighttpd.html
      No default index.lighttpd.html file found... not backing up

  [✓] Installing sudoer file

  [✓] Installing latest Cron script

  [✓] Installing latest logrotate script
  [i] Backing up /etc/dnsmasq.conf to /etc/dnsmasq.conf.old
  [✓] man pages installed and database updated

I've installed ufw with the usual open ports for pihole, I tried to switch it off, didn't make any difference however.

what is happening here, and how can I get those services to run again?
Thanks for any help!

Please upload a debug log and post just the token that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:

pihole -d

or do it through the Web interface:

Tools > Generate Debug Log

https://tricorder.pi-hole.net/v1eod45qdu

Thanks for replying. Is this what you requested?

All failures seem to point in this direction:
ifup: failed to bring up venet0:0

I did the install procedure again, starting from fresh installed debian 10 system, a situation where all services are working, (no red lines). I installed pihole. (curl -sSL https://install.pi-hole.net | bash) Just after the fresh pihole installation I did another: pihole -d

Same situation as in the picture.

Find the results for the new log:
https://tricorder.pi-hole.net/lftoe2iwht

After rebooting:
networking.service:

Starting Raise network interfaces...
Waiting for DAD... Done
RTNETLINK answers: File exists
ifup: failed to bring up venet0:0
networking.service: Main process exited, code=exited, status=1/FAILURE
networking.service: Failed with result 'exit-code'.
Failed to start Raise network interfaces.

[ DIAGNOSING ]:e[Networking IPv4 address(es) bound to the venet0 interface:  
127.0.0.1/32e does not match the IP found in /etc/pihole/setupVars.conf  (ehttps://discourse.pi-hole.net/t/use-ipv6-ula-addresses-for-pi-hole/2127e)
194.5.159.139/24e matches the IP found in /etc/pihole/setupVars.conf

Run pihole -r and select the reconfigure option to get Pi-hole setup on the correct interface and IP.

OK. I just did exactly that. pihole -r and reconfigure. So, the same installation script again, without changing anything to the script. This time I chose google's 8.8.8.8 for the DNS server configuration during installation, and previously to running the script, I pinged 8.8.8.8 on port 53 on the server terminal by the command:
"dig pi-hole.net (at)8.8.8.8 -p 53"
It answered "Yes, answer from 8.8.8.8" So I knew there was a DNS reply and this could not be the problem while running the script or afterwards.

The reconfiguration finished, but the same errors appeared again afterwards, as in the first image of the previous attempt. After rebooting the server the same red lines came up in services for the same services. So, After reconfiguration there was the same situation, which is logical, nothing was changed before pihole installation.

networking.service: Failed to start Raise network interfaces.

the new debug log:
https://tricorder.pi-hole.net/lmmk2vww0z

ps. I could upload the /etc/pihole/setupVars.conf
file for you, but that is not really secure I guess

Can no one help me with this?

Since the lighttpd.service is not running as well (because of raise network problem I think) there is not much I can with pihole, and I can't bypass the problem. Am I really the only debian 10 user with this?

Couple things I see from your original post:

  1. Looks like you are running static IP, so why is dhcpcd.service running? Might help to see the contents of your /etc/network/interfaces file.
  2. apache2.service is running. That will likely be an issue for lighttpd.

I'd try stopping those two services....
systemctl stop apache2 dhcpcd

You've configured your Pi-hole for a public IP address

[ DIAGNOSING ]:[Networking IPv4 address(es) bound to the venet0 interface:  
194.xxx.xxx.139/24 matches the IP found in /etc/pihole/setupVars.conf

Note that exposing Pi-hole's host via a public IP address may turn your Pi-hole into an open resolver, which poses a potential threat for all Internet users, e.g. by serving as a multiplier in a DNS Amplification attack.

The Pi-hole team strongly discourages Pi-hole’s usage as an open resolver, and we won't provide support in that case.

That said, I'd somehow guess your venet0 and venet0:0 to be tunnel interfaces for VPN connections.
Are you perhaps already trying to make your VPS Pi-hole accessible via VPN only?

In that case, you should configure Pi-hole for the private IP address bound to your VPN tunnel interface (which should have no public IP at all). You may also refer to our guides for further suggestions, e.g. for OpenVPN or Wireguard.

Guys, in the last 2 days I needed my time elsewhere, so this is a later reply.
Thanks you both for the arguments. Rutrow, by simply stopping and uninstalling the 2 services like you suggested. I solved the problem! Just reboot the thing and all red lines disappeared in the systemctl service list. Pihole started running perfectly.
To answer you worry. No I am not installing a DDOS attack machine, there is a firewall on top of it and no open queries are allowed.
Thanks very much!

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