howto use netplan in ubuntu 20.04 with 2 lan interfaces + policy based routing

2 Internet providers.

2nd network cards.

Each one accesses the Internet through its own router (its own provider).

Cards with static IP:

eth1 – 192.168.1.11 gate1 – 192.168.1.1

eth2 – 192.168.100.12 gate2 – 192.168.100.1

Did you ask? We answer!

You need to make sure that the package iproute2 is installed on your system.

apt install iproute2

Edit /etc/iproute2/rt_tables, add these lines

101 101
102 102

Then edit /etc/netplan/ in my case it’s a file 99-netplan.yaml

network:
    version: 2
    renderer: networkd
    ethernets:
        eth1:
            addresses:
             - 192.168.1.11/24
            dhcp4: no
            nameservers:
              addresses:
                - 192.168.1.1
                - 8.8.8.8
            routes:
             - to: default
               via: 192.168.1.1
             - to: 192.168.1.11/24
               via: 192.168.1.1
               table: 101
            routing-policy:
             - from: 192.168.1.11/24
               table: 101
        eth2:
            addresses:
             - 192.168.100.12/24
            dhcp4: no
            nameservers:
              addresses:
                - 192.168.100.1
                - 8.8.4.4
            routes:
             - to: 192.168.100.0/24
               via: 192.168.100.1
               table: 102
            routing-policy:
             - from: 192.168.100.0/24
               table: 102

Check config of netplan

netplan generate

If there are no errors, then enter the command

netplan apply

That’s all. Policy based routing is configured.

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