routing – How one can repair IPv4 routes in Community Supervisor `nmcli` so I haven’t got to manually `ip route delete` the route Community Supervisor creates?

I’ve a community system with each:

1. Mobile Web through modem (I would like this to work 100% of the time for Web entry)
2. Ethernet interface for Modbus TCP connection

The mobile connection is created with this command:

$ sudo nmcli c add sort gsm con-name telus 
    ipv4.dns '8.8.8.8 8.8.4.4' autoconnect sure 
    ifname 'cdc-wdm0' apn 'isp.telus.com' 
    ipv4.route-metric 1

$ sudo nmcli con up telus

The Modbus ethernet connection is created like this:

$ sudo nmcli con add sort ethernet con-name modbus 
    ifname enp1s0 connection.autoconnect sure 
    ipv4.never-default sure 
    ip4.addresses '10.1.9.7/16, 10.1.9.7/8' 
    ipv4.routes '10.1.0.0/16 10.1.10.1, 10.0.0.0/8 10.1.10.1' 
    ipv4.route-metric 800

$ sudo nmcli con up modbus

At this level, the ping check fails:

$ ping -c 1 10.65.3.5
PING 10.65.3.5 (10.65.3.5) 56(84) bytes of information.
^C
--- 10.65.3.5 ping statistics ---
1 packets transmitted, 0 obtained, 100% packet loss, time 0ms

The Hacky Resolution:

I’ve to manually delete one of many routes Community Supervisor creates with ip route:

$ sudo ip route delete 10.0.0.0/8 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7 metric 800

Nice success!

$ ping -c 1 10.65.3.5
PING 10.65.3.5 (10.65.3.5) 56(84) bytes of information.
64 bytes from 10.65.3.5: icmp_seq=1 ttl=126 time=117 ms

--- 10.65.3.5 ping statistics ---
1 packets transmitted, 1 obtained, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 117.203/117.203/117.203/0.000 ms

However I am anxious…

I believe this answer is just momentary, till Community Supervisor places the route again once more…

How one can persist the working configuration so I haven’t got to manually delete the route? It retains popping up once more, as a result of Community Supervisor retains placing it again.

Working routes, after deleting the unhealthy route that makes the ping check fail:

$ sudo ip route delete 10.0.0.0/8 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7 metric 800

$ ip route
default through 10.96.241.146 dev wwan proto static metric 1
10.0.0.0/8 through 10.1.10.1 dev enp1s0 proto static metric 800
10.1.0.0/16 through 10.1.10.1 dev enp1s0 proto static metric 800
10.1.0.0/16 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7 metric 800
10.96.241.144/30 dev wwan proto kernel scope hyperlink src 10.96.241.145 metric 1

Notice the next route isn’t there anymore, but it surely retains getting put again…

10.0.0.0/8 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7 metric 800

Because of this reply, I’ve since added the next script to “/and so forth/NetworkManager/dispatcher.d/99-kill-bad-route.sh”, which can also be sort of hacky…

#!/bin/bash

if [ "$1" == "enp1s0" ] && [ "$2" == "up" ]; then
    ip route del 10.0.0.0/8 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7 metric 800
fi

Can the above answer be achieved with a Community Supervisor nmcli command as a substitute?

This is how I automated the answer with Python:

from pathlib import Path
import subprocess


def add_script_to_auto_delete_problem_route(
    counter: int,
    bad_network: str,
    ip_address: str,
    interface: str = "enp1s0",
) -> None:
    """
    sudo nano /and so forth/NetworkManager/dispatcher.d/9x-delete-problem-route.sh
    #!/bin/bash

    if [ "$1" == "enp1s0" ] && [ "$2" == "up" ]; then
        ip route del 10.0.0.0/8 dev enp1s0 proto kernel scope hyperlink src 10.1.9.7
    fi
    """
    file_path: Path = Path(
        f"/and so forth/NetworkManager/dispatcher.d/9{counter}-delete-problem-route-modbus.sh"
    )
    script: str = f"""#!/bin/bash

if [ "$1" == "{interface}" ] && [ "$2" == "up" ]; then
    ip route del {bad_network} dev {interface} proto kernel scope hyperlink src {ip_address}
fi
"""
    print(
        "Including script to '%s' to delete drawback route '%s'...",
        file_path,
        bad_network,
    )
    if not file_path.mother or father.exists():
        file_path.mother or father.mkdir(dad and mom=True, exist_ok=True)
    if not file_path.exists():
        file_path.contact()
    with open(file_path, "w", encoding="utf-8") as file:
        file.write(script)

    # Make the file executable
    command_list: checklist = ["sudo", "chmod", "+x", str(file_path)]
    print("Operating command '%s' to make the script executable...", command_list)
    subprocess.run(command_list, shell=False)

    return None