nat

README

NAT IOModule

This module is a NAT that implements source address translation. In particular PAT algorithm is applied: source IP Address and Ports are changed in order to hide intern private ip addresses and exit on the internet (or another network) with only one public IP address.

notes:

• first port is always attached to internal network, second port to external one.
• nat iomodule should be part of the code of the router. This is not possible for framework issues (hover does not allow to use 1+ eBPF programs inside the same iomodule).
• this is a transparent nat:
• always attach a nat to a router.
• the layer 2 (arp request, layer 2 rewrite) is managed by the router.
• the nat only modifies packet layers 3-4

API:

• SetPublicIp(ip string): Set public ip address
• ip: public ip address. (e.g. 10.10.1.100)

How to use

Using iovisor-ovn daemon in standalone mode, the user can deploy and configure a single or a chain of IOModules. The entire setup can be deployed starting from a YAML configuration file.

$GOPATH/bin/iovisorovnd -file <configuration.yaml>

Some examples are available in /examples folder:

• Nat and Router

Please note that NAT IOModule Must be deployed attached to a Router.

YAML Configuration Format

The following is an example of the configuration of a NAT:

[...]
- name: Nat
type: nat
config:
public_ip: 10.10.1.100

[...]

• public_ip: defines public ip address.

Limitations

• The first port of the nat is always attached to the internal network.
• The second port of the nat is always attached to the public network.
• No cleanup is performed on the nat tables entries
• The mechanism to choose the source port is incremental starting from port 1025.

Documentation

Overview

Copyright 2017 Politecnico di Torino

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Copyright 2017 Politecnico di Torino

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Index

• Variables
• type NatModule
  • func Create(hc *hover.Client) *NatModule
  • func (n *NatModule) AttachExternalInterface(ifaceName string) (err error)
  • func (n *NatModule) AttachToIoModule(ifaceId int, ifaceName string) (err error)
  • func (n *NatModule) Configure(conf interface{}) (err error)
  • func (n *NatModule) Deploy() (err error)
  • func (n *NatModule) Destroy() (err error)
  • func (n *NatModule) DetachExternalInterface(ifaceName string) (err error)
  • func (n *NatModule) DetachFromIoModule(ifaceName string) (err error)
  • func (n *NatModule) GetModuleId() string
  • func (n *NatModule) SetPublicIp(ip net.IP) (err error)
• type NatModuleInterface

Variables

var NatCode = `` /* 16194-byte string literal not displayed */

Types

type NatModule

type NatModule struct {
	ModuleId   string
	PortsCount int //number of allocated ports
	Interfaces map[string]*NatModuleInterface
	// contains filtered or unexported fields
}

func Create

func Create(hc *hover.Client) *NatModule

func (*NatModule) AttachExternalInterface

func (n *NatModule) AttachExternalInterface(ifaceName string) (err error)

func (*NatModule) AttachToIoModule

func (n *NatModule) AttachToIoModule(ifaceId int, ifaceName string) (err error)

func (*NatModule) Configure

func (n *NatModule) Configure(conf interface{}) (err error)

func (*NatModule) Deploy

func (n *NatModule) Deploy() (err error)

func (*NatModule) Destroy

func (n *NatModule) Destroy() (err error)

func (*NatModule) DetachExternalInterface

func (n *NatModule) DetachExternalInterface(ifaceName string) (err error)

func (*NatModule) DetachFromIoModule

func (n *NatModule) DetachFromIoModule(ifaceName string) (err error)

func (*NatModule) GetModuleId

func (n *NatModule) GetModuleId() string

func (*NatModule) SetPublicIp

func (n *NatModule) SetPublicIp(ip net.IP) (err error)

type NatModuleInterface

type NatModuleInterface struct {
	IfaceIdRedirectHover int    //Iface id inside hover (relative to the m:1234 the interface is attached to ...) and provided my the extended hover /links/ API
	IfaceFd              int    //Interface Fd inside External_Ids (42, etc...)
	LinkIdHover          string //iomodules Link Id
	IfaceName            string
}