Revert "prevent ingress creation on NATed host (#2395)" (#2422)

This reverts commit 20998dd6131e4957c36754ab82d9f2da1417c9d2.

logic/gateway.go

@@ -115,9 +115,6 @@ func CreateIngressGateway(netid string, nodeid string, ingress models.IngressReq
 	if host.FirewallInUse == models.FIREWALL_NONE {
 		return models.Node{}, errors.New("firewall is not supported for ingress gateways")
 	}
-	if host.NatType != models.NAT_Types.Public {
-		return models.Node{}, errors.New("ingress cannot be created on nodes behind NAT")
-	}
 
 	network, err := GetParentNetwork(netid)
 	if err != nil {