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Charlweed
Asked: 2021-09-13 09:11:57 +0800 CST

Preferred way to copy route configuration to different host?

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I'm replacing a CentOS server with an Ubuntu 20 one. I need to duplicate the older servers routing configuration. The outputs of ip route show and route are not directly usable as inputs.

I'm a bit reluctant to hand-translate the output into route commands, because errors always creep in. Is there a better way?

networking

1 Answers

  1. I'm going to try a powershell script. route shows the current routing tables as a table with these columns: Destination,Gateway,Genmask,Flags,Metric,Ref,Use,Iface

    So I saved that output to a file, and copied it to the new host. I converted the raw output to a csv file by removing the first line, and replacing the spaces with a comma. I also replaced the device names with ones that matched on the new system. So my test route table might look like this:

    Destination,Gateway,Genmask,Flags,Metric,Ref,Use,Iface
default,gateway,0.0.0.0,UG,0,0,0,enp5s0
default,toblerone.mydomain.org,0.0.0.0,UG,100,0,0,eno1
192.168.0.0,0.0.0.0,255.255.255.0,U,100,0,0,eno1
192.168.1.0,0.0.0.0,255.255.255.0,U,0,0,0,enp5s0
192.168.1.0,gateway,255.255.255.0,UG,0,0,0,enp5s0

    The route command can produce unexpected errors when the route already exists. I also don't want the generated commands to run directly. So my PowerShell script looks like this:

    #!/usr/bin/env pwsh

Set-StrictMode -Version Latest

$ErrorActionPreference = "Stop"
$PSDefaultParameterValues['Set-*:ErrorAction'] = "Stop"

$routeDataCSV = Import-CSV "./route_data.csv"
# A route should only be deleted once per run.
$routeDeleted = @{}

foreach ($routeIn in $routeDataCSV) {
    if (!$routeDeleted[$routeIn.Destination] -or (!($routeDeleted[$routeIn.Destination] -like "true"))) {
        Write-Output "route del -net $($routeIn.Destination)"
        $routeDeleted[$routeIn.Destination] = "true"
    }
    Write-Output "route add -net $($routeIn.Destination) gw $($routeIn.Gateway) netmask $($routeIn.Genmask) metric $($routeIn.Metric) dev $($routeIn.Iface)"
}

    The generated commands are then:

    route del -net default
route add -net default gw gateway netmask 0.0.0.0 metric 0 dev enp5s0
route add -net default gw toblerone.mydomain.org netmask 0.0.0.0 metric 100 dev eno1
route del -net 192.168.0.0
route add -net 192.168.0.0 gw 0.0.0.0 netmask 255.255.255.0 metric 100 dev eno1
route del -net 192.168.1.0
route add -net 192.168.1.0 gw 0.0.0.0 netmask 255.255.255.0 metric 0 dev enp5s0
route add -net 192.168.1.0 gw gateway netmask 255.255.255.0 metric 0 dev enp5s0
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