[Solved] Buster- networking.service fails to start

[tperica]

Hi to all,
I have a problem with networking service on Debian 10(Buster), VPS server. I tried to search but to no avail.

The problem: networking.service fails to start!?

Network, ssh connection, iptables, psad, etc are working as configured.The ufw service shows a problem with "chain ufw-not-local", but ufw status verbose && restating the service works. I have disabled ipv6 via /etc/sysctl.conf and grub, though, but does not seem as a problem.

Commands are showing proper name 'eth0'

$/etc/networking/interfaces
$ ls /sys/class/net/
$ ifconfig -a
$ ip a
$ fquery eth0

root@hostname:~# ifup eth0
RTNETLINK answers: File exists
ifup: failed to bring up eth0

#systemd log
$journalctl -xe
-- Subject: A start job for unit networking.service has begun execution
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- A start job for unit networking.service has begun execution.
--
-- The job identifier is 213.
Sep 07 15:47:38 xxxx(hostname) ifup[21005]: RTNETLINK answers: File exists
Sep 07 15:47:38 xxxx(hostname) ifup[21005]: ifup: failed to bring up eth0
Sep 07 15:47:38 xxxx(hostname) systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
-- Subject: Unit process exited
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- An ExecStart= process belonging to unit networking.service has exited.
--
-- The process' exit code is 'exited' and its exit status is 1.
Sep 07 15:47:38 xxxx(hostname) systemd[1]: networking.service: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- The unit networking.service has entered the 'failed' state with result 'exit-code'.
Sep 07 15:47:38 xxxx(hostname) systemd[1]: Failed to start Raise network interfaces.
-- Subject: A start job for unit networking.service has failed
-- Defined-By: systemd
-- Support: https://www.debian.org/support
--
-- A start job for unit networking.service has finished with a failure.

Any way I can solve or debug this problem?

Regards,
Tomislav

[tperica]

just misconfigured /etc/hosts for particular VPS provider

disregard >>
In Stretch disabling ipv6 worked by:
$ vim /etc/sysctl.conf
Add the following at the bottom of the file:
$ net.ipv6.conf.all.disable_ipv6 = 1
$ net.ipv6.conf.default.disable_ipv6 = 1
$ net.ipv6.conf.lo.disable_ipv6 = 1
$ sysctl -p

&& GRUB line in /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"
$ update-grub

In Buster, at least for now, there is an additional step,
$ vim /etc/network/interfaces
comment out
#iface eth0 inet6 static
#address xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
#netmask 64
#gateway xxxx::x
#accept_ra 0
#autoconf 0
#privext 0

The networking service is loaded at the boot && everything works.

Regards,
Tomislav