This bug was initially created as a copy of Bug #1722873

I am copying this bug because issue exists in RHEL8 for 35network-legacy module:

35network-legacy/ifup.sh:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
            if command -v arping2 >/dev/null; then
                if arping2 -q -C 1 -c 2 -I $netif -0 $ip ; then
                    warn "Duplicate address detected for $ip for interface $netif."
                    return 1
                fi
            else
                if ! arping -f -q -D -c 2 -I $netif $ip ; then
                    warn "Duplicate address detected for $ip for interface $netif."
                    return 1
                fi
            fi
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------


Description of problem:

In dracut's 40network module, arping is used to detect Duplicate addresses :

40network/ifup.sh:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
            if ! arping -f -q -D -c 2 -I $netif $ip; then
                warn "Duplicate address detected for $ip for interface $netif."
                return 1
            fi
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

40network/dhclient-script.sh code:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
            if ! arping -f -q -D -c 2 -I $netif $new_ip_address ; then
                warn "Duplicate address detected for $new_ip_address while doing dhcp. retrying"
                exit 1
            fi
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

For some reason, if the network interface is not available, in particular in the "ifup.sh" case (because for dhclient, it's retried), arping will print "Device XXX not available" but then dracut will abort and print "Duplicate address detected" which is not the real error.


Version-Release number of selected component (if applicable):

All dracut version, including RHEL8's one


How reproducible:

Don't know how to reproduce arping's "Device XXX not available" error


Additional info:

arping returns exit(2) upon device error and other errors (mostly getopt errors), whereas exit(1) is returned when a duplicate address is found:

exit(2):
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
int
main(int argc, char **argv)
{
[...]
                        fprintf(stderr, "arping: Device %s not available.\n", device.name);
                        exit(2);
[...]
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

exit(1) (Duplicate address detection, dad == 1):
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
void finish(void)
{
        if (!quiet) {
                printf("Sent %d probes (%d broadcast(s))\n", sent, brd_sent);
                printf("Received %d response(s)", received);
[...]
        if (dad)
                exit(!!received);
[...]
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Dracut code should distinguish between rc == 2 and rc == 1 instead of using "! arping" test condition.