tuntap

Documentation

Overview

Package tuntap provides a portable interface to create and use TUN/TAP virtual network interfaces.

Note that while this package lets you create the interface and pass packets to/from it, it does not provide an API to configure the interface. Interface configuration is a very large topic and should be dealt with separately.

Index

• Constants
• Variables
• type DevKind
• type Interface
  • func Open(ifPattern string, kind DevKind) (*Interface, error)
  • func (t *Interface) AddAddress(ip net.IP, subnet *net.IPNet) error
  • func (t *Interface) Close() error
  • func (t *Interface) GetAddrList() ([][]byte, error)
  • func (t *Interface) IPv6(ctrl bool) error
  • func (t *Interface) IPv6Forwarding(ctrl bool) error
  • func (t *Interface) IPv6SLAAC(ctrl bool) error
  • func (t *Interface) Name() string
  • func (t *Interface) ReadPacket(buffer []byte) (Packet, error)
  • func (t *Interface) SetMTU(mtu int) error
  • func (t *Interface) Up() error
  • func (t *Interface) WritePacket(pkt Packet) error
• type Packet
  • func (p *Packet) DIP() net.IP
  • func (p *Packet) DSCP() int
  • func (p *Packet) ICMPType() (int, int, int)
  • func (p *Packet) IPProto() (uint8, int, bool)
  • func (p *Packet) SIP() net.IP
  • func (p *Packet) String() string

Constants

const (
	// various ethernet protocols, using the same names as linux does
	ETH_P_IP   uint16 = 0x0800
	ETH_P_IPV6 uint16 = 0x86dd
)

Variables

var ErrJumboPacket = errors.New("jumbo packet too large for /dev/tun")

var ErrShortRead = errors.New("truncated /dev/tun read")

Types

type DevKind

type DevKind int

const (
	// Receive/send layer routable 3 packets (IP, IPv6...). Notably,
	// you don't receive link-local multicast with this interface
	// type.
	DevTun DevKind = iota
	// Receive/send Ethernet II frames. You receive all packets that
	// would be visible on an Ethernet link, including broadcast and
	// multicast traffic.
	DevTap
)

type Interface

type Interface struct {
	// contains filtered or unexported fields
}

func Open

func Open(ifPattern string, kind DevKind) (*Interface, error)

Open connects to the specified tun/tap interface.

If the specified device has been configured as persistent, this simply looks like a "cable connected" event to observers of the interface. Otherwise, the interface is created out of thin air.

ifPattern can be an exact interface name, e.g. "tun42", or a pattern containing one %d format specifier, e.g. "tun%d". In the latter case, the kernel will select an available interface name and create it.

Returns a TunTap object with channels to send/receive packets, or nil and an error if connecting to the interface failed.

func (*Interface) AddAddress

func (t *Interface) AddAddress(ip net.IP, subnet *net.IPNet) error

AddAddress adds an IP address to the tunnel interface.

func (*Interface) Close

func (t *Interface) Close() error

Disconnect from the tun/tap interface.

If the interface isn't configured to be persistent, it is immediately destroyed by the kernel.

func (*Interface) GetAddrList

func (t *Interface) GetAddrList() ([][]byte, error)

GetAddrList returns the IP addresses (as bytes) associated with the interface.

func (*Interface) IPv6

func (t *Interface) IPv6(ctrl bool) error

IPv6 enables/disable ipv6 for the interface.

func (*Interface) IPv6Forwarding

func (t *Interface) IPv6Forwarding(ctrl bool) error

IPv6Forwarding enables/disables ipv6 forwarding for the interface.

func (*Interface) IPv6SLAAC

func (t *Interface) IPv6SLAAC(ctrl bool) error

IPv6SLAAC enables/disables stateless address auto-configuration (SLAAC) for the interface.

func (*Interface) Name

func (t *Interface) Name() string

The name of the interface. May be different from the name given to Open(), if the latter was a pattern.

func (*Interface) ReadPacket

func (t *Interface) ReadPacket(buffer []byte) (Packet, error)

Read a single packet from the kernel.

func (*Interface) SetMTU

func (t *Interface) SetMTU(mtu int) error

SetMTU sets the tunnel interface MTU size.

func (*Interface) Up

func (t *Interface) Up() error

Up sets the tunnel interface to the UP state.

func (*Interface) WritePacket

func (t *Interface) WritePacket(pkt Packet) error

Send a single packet to the kernel.

type Packet

type Packet struct {
	// The raw bytes of the Ethernet payload (for DevTun) or the full
	// Ethernet frame (for DevTap).
	Body []byte
	// The Ethernet type of the packet. Commonly seen values are
	// 0x8000 for IPv4 and 0x86dd for IPv6.
	Protocol uint16
	// True if the packet was too large to be read completely.
	Truncated bool
}

func (*Packet) DIP

func (p *Packet) DIP() net.IP

return the destination IP

func (*Packet) DSCP

func (p *Packet) DSCP() int

return the 6-bit DSCP field

func (*Packet) ICMPType

func (p *Packet) ICMPType() (int, int, int)

returns ipproto, icmp type, icmp code, if this is an ICMP packet, or 0,_,_ if it isn't

func (*Packet) IPProto

func (p *Packet) IPProto() (uint8, int, bool)

return the IP protocol, the offset to the IP datagram payload, and true if the payload is from a non-first fragment returns 0,0,false if parsing fails or 0,len(Body),false if the IPv6 header 59 (no-next-header) is found

func (*Packet) SIP

func (p *Packet) SIP() net.IP

return the source IP

func (*Packet) String

func (p *Packet) String() string