If both ipv4 iptables fails and ipv6 tables fail, the failure reason is lost

[joejulian]

plugins/plugins/meta/portmap/portmap.go

Lines 125 to 127 in b8a10bb

	if ip4t == nil && ip6t == nil {
	return fmt.Errorf("neither iptables nor ip6tables usable")
	}

If maybeGetIptables for both ipv4 and ipv6 returns nil, a generic error is returned that doesn't help the user diagnose the problem. If only one of them fails, it appears that a much more helpful error is generated.

plugins/plugins/meta/portmap/portmap.go

Lines 130 to 132 in b8a10bb

	if err := dnatChain.check(ip4t); err != nil {
	return fmt.Errorf("could not check ipv4 dnat: %v", err)
	}

Should those more helpful errors also be generated for the double failure?