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Zentori
Asked: 2024-09-29 03:12:43 +0800 CST

Define custom route with NetworkManager in AlmaLinux 9

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In AlmaLinux 9 NetworkManager should be used to define connections. In the datacenter we use a route has to be defined in order to use custom IP from virtual machine. I have made progress defining IPs in host, but couldn't manage to have NetworkManager creating the route upon restart, but with this command network is working:

ip route add default via 192.168.0.1 dev ens18 onlink src 94.23.81.XXX

I'm not familiar with nmconnection file format so I couldn't make it with NetworkManager. Where should I put this command or in which file could I define this default and only route?

Thanks.

routing

1 Answers

  1. Best Answer

    This documentation contains a variety of examples of how to use nmcli to create static routes. It doesn't cover the use of custom attributes like onlink, but we can find that in the nmcli documentation, which tells us that the value of the ipv4.routes option is:

    A list of IPv4 destination addresses, prefix length, optional IPv4 next hop addresses, optional route metric, optional attribute. The valid syntax is: "ip[/prefix] [next-hop] [metric] [attribute=val]...[,ip[/prefix]...]". For example "192.0.2.0/24 10.1.1.1 77, 198.51.100.0/24".

    Suggesting that we can do this (assuming that we have a connection named wired, which I do):

    nmcli c mod wired +ipv4.routes "192.168.55.0/24 192.168.1.1 onlink=true"

    Which, when I run it on my system, results in:

    192.168.55.0/24 via 192.168.1.1 dev eth0 proto static metric 100 onlink

    Note that you will need to nmcli down/nmcli up the connection for the changes to be realized.

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