I'm setting up an Ubuntu Server 20.04 system as a gateway between my LAN and the WAN. I'm not able to configure the DNS properly.
I have 2 netplan config files for my 2 interfaces.
Internal eth interface (LAN)
root@gate:~# cat /etc/netplan/01-eth_int.yaml
# This is the network config written by 'subiquity'
network:
ethernets:
enp4s0:
addresses: ['10.0.10.1/24']
match:
macaddress: 00:60:e0:76:9e:e7
set-name: eth_int
version: 2
External eth interface (WAN)
root@gate:~# cat /etc/netplan/02-eth_ext.yaml
# This is the network config written by 'subiquity'
network:
ethernets:
enp5s0:
addresses: ['10.200.56.254/24']
gateway4: 10.200.56.1
nameservers:
addresses: [195.78.215.228, 195.78.223.228]
addresses: [8.8.8.8, 8.8.4.4]
match:
macaddress: 00:60:e0:76:9e:e8
set-name: eth_ext
version: 2
On reboot the interfaces are configured according to netplan config files. But /etc/resolv.conf is misconfigured
root@gate:~# cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 127.0.0.53
options edns0
Test/check performed:
- /etc/resolv.conf is a symlink of ../run/systemd/resolve/stub-resolv.conf
- systemd-resolve --status returns the correct DNS for eth_ext interface, but no global DNS (can be an issue?)
root@gate:~# systemd-resolve --status
Global
LLMNR setting: no
MulticastDNS setting: no
DNSOverTLS setting: no
DNSSEC setting: no
DNSSEC supported: no
DNSSEC NTA: 10.in-addr.arpa
16.172.in-addr.arpa
168.192.in-addr.arpa
17.172.in-addr.arpa
18.172.in-addr.arpa
19.172.in-addr.arpa
20.172.in-addr.arpa
21.172.in-addr.arpa
22.172.in-addr.arpa
23.172.in-addr.arpa
24.172.in-addr.arpa
25.172.in-addr.arpa
26.172.in-addr.arpa
27.172.in-addr.arpa
28.172.in-addr.arpa
29.172.in-addr.arpa
30.172.in-addr.arpa
31.172.in-addr.arpa
corp
d.f.ip6.arpa
home
internal
intranet
lan
local
private
test
Link 5 (eth_ext)
Current Scopes: DNS
DefaultRoute setting: yes
LLMNR setting: yes
MulticastDNS setting: no
DNSOverTLS setting: no
DNSSEC setting: no
DNSSEC supported: no
DNS Servers: 195.78.215.228
195.78.223.228
8.8.8.8
8.8.4.4
Link 4 (enp0s31f6)
Current Scopes: none
DefaultRoute setting: no
LLMNR setting: yes
MulticastDNS setting: no
DNSOverTLS setting: no
DNSSEC setting: no
DNSSEC supported: no
Link 3 (eth_int)
Current Scopes: none
DefaultRoute setting: no
LLMNR setting: yes
MulticastDNS setting: no
DNSOverTLS setting: no
DNSSEC setting: no
DNSSEC supported: no
Link 2 (enp3s0)
Current Scopes: none
DefaultRoute setting: no
LLMNR setting: yes
MulticastDNS setting: no
DNSOverTLS setting: no
DNSSEC setting: no
DNSSEC supported: no
- edited /etc/systemd/resolved.conf, setting and uncommenting DNS entry. A global DNS entry appears running systemd-resolve --status, but /etc/resolv.conf won't change
Obviously, this mismatch will prevent DNS to work properly
root@gate:~# ping google.com
ping: google.com: Temporary failure in name resolution
root@gate:~# nslookup heise.de 127.0.0.53
;; connection timed out; no servers could be reached
How can I solve this?
nslookup google.com 195.78.218.228give you?