1

I have a requirement and this was working (up to 2020) without issue. As my installs were outdated and I didn't care to actually UPGRADE, I decided to blitz the lot and begin with fresh installs using Ubuntu 23.04 for servers and 24.04 for my desktop.

I am creating this via Virtualbox setup and have two host-only networks: 192.168.110.x and 192.168.120.x. Any server installs will be in either 110 or 120.

The desktop has 3 NICs:

  • enp0s3=NAT (10.0.2.15)
  • enp0s8=192.168.110.3
  • enp0s9=192.168.120.3.

I have set IP forwarding on the desktop to route 110 and 120 through enp0s3 using IP tables.

All this was working when gateway was a valid declaration in netplan. However, now the setup is different, I have been looking at the netplan examples provided via a different question and can find nothing which might match MY needs. I am finding it a bit confusing to work out the routing declarations for each network.

As an aside, rather than declaring nameservers twice, can I somehow just specify it once for all ethernets?

  1 # Let NetworkManager manage all devices on this system
  2 network:
  3   version: 2
  4   renderer: NetworkManager
  5   ethernets:
  6     enp0s8: #Edit this line according to your network interface name.
  7       dhcp4: no
  8       addresses:
  9         - 192.168.110.3/24
 10         routes:
 11         - to: default
 12           via: 192.168.110.1
 13       nameservers:
 14         addresses:
 15           - 8.8.8.8
 16           - 8.8.4.4
 17     enp0s9: #Edit this line according to your network interface name.
 18       dhcp4: no
 19       addresses:
 20         - 192.168.120.3/24
 21         routes:
 22         - to: default
 23           via: 192.168.120.1
 24       nameservers:
 25         addresses:
 26           - 8.8.8.8
 27           - 8.8.4.4
 28

The error I am getting is:

Problem encountered while validating default route consistency.Please set up multiple routing tables and use routing-policy instead.

Error: Conflicting default route declarations for IPv4 (table: main, metric: default), first declared in enp0s8 but also in enp0s9

Improve this question
3
  • Having multiple default routes doesn't make any sense: the default route is the route of last resort and there can be only one. You would run into a similar error if you were to try to manually add multiple default routes using ip route add. Commented Mar 7, 2024 at 15:43
  • Thanks. I understand that. The old method was simple: NIC address, netmask, gateway. I am a bit confused with this new method as to what 'gateway' is now defined as. Commented Mar 8, 2024 at 7:18
  • A default route has to be associated with an interface. A global "gateway" setting didn't make sense because it wasn't associated with an interface. If you previously had a single "gateway", then now one of your interfaces would define a default route. Commented Mar 8, 2024 at 13:07

2 Answers 2

Reset to default
1

Here's the text output from @Ramya's screen shot:

network:
  ethernets:
    ens160: #Edit this line according to your network interface name
      addresses:
        - 10.20.10.134
      nameservers:
        addresses:
          - 10.20.10.150/25
          - 8.8.8.8
      routes:
        - to: default #This is Default Route
          via: 10.20.10.129

    ens192: #Edit this line according to your network interface name
      addresses:
        - 198.168.0.134/16
      nameservers:
        addresses:
          - 198.168.0.100
      routes:
        - to: 198.168.0.0/16
          via: 198.168.0.254 #This is the routing entry for 198.168.x/16 network

    ens224: #Edit this line according to your network interface name
      addresses:
        - 199.168.0.134/16
      nameservers:
        addresses:
          - 199.168.0.100
      routes:
        - to: 199.168.0.0/16
          via: 199.168.0.254. #This is the routing entry for 199.168.x/16 network

version: 2
Improve this answer
0

Make sure there is only one route as default route. The below config works fine:

enter image description here

Improve this answer
1
  • 2
    Welcome to the site. Please don't post screenshots of console output. They are often difficult to read, the content will not show up in search engine results, and the OP will need to type-copy command examples when trying to apply your solution. Instead, paste it into the question using code formatting. Commented Jul 15, 2024 at 14:23

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.