mtu

Documentation

Index

• Constants
• func CalculateMTU(pathMTU int, isIPv6 bool, tunnelMode bool) int
• func CalculateWireGuardMTU(pathMTU int, isIPv6 bool) int
• type Discoverer
  • func NewDiscoverer(target net.IP, log *output.Logger, minMTU, maxMTU int) *Discoverer
  • func (d *Discoverer) FindPathMTU() (int, error)

Constants

const (
	// IP_MTU_DISCOVER is the Linux socket option for MTU discovery
	IP_MTU_DISCOVER = 10
	// IP_PMTUDISC_DO enables PMTU discovery and sets Don't Fragment bit
	IP_PMTUDISC_DO = 2
)

const (
	// MinMTU_IPv4 is the minimum MTU for IPv4 networks (RFC 791)
	MinMTU_IPv4 = 576
	// MinMTU_IPv6 is the minimum MTU for IPv6 networks (RFC 8200)
	MinMTU_IPv6 = 1280
	// MaxMTU is the standard Ethernet MTU
	MaxMTU = 1500
	// ICMPHeaderSize is the size of ICMP header
	ICMPHeaderSize = 8
	// IPv4HeaderSize is the size of IPv4 header
	IPv4HeaderSize = 20
	// IPv6HeaderSize is the size of IPv6 header
	IPv6HeaderSize = 40
)

const (
	// WireGuardOverheadIPv4 is the overhead for WireGuard over IPv4
	// (20 bytes IPv4 + 8 bytes UDP + 32 bytes WireGuard)
	WireGuardOverheadIPv4 = 60

	// WireGuardOverheadIPv6 is the overhead for WireGuard over IPv6
	// (40 bytes IPv6 + 8 bytes UDP + 32 bytes WireGuard)
	WireGuardOverheadIPv6 = 80
)

WireGuard overhead constants WireGuard adds the following overhead to each packet: - IPv4/IPv6 header (20/40 bytes) - UDP header (8 bytes) - WireGuard header (32 bytes)

Total overhead: - IPv4: 20 + 8 + 32 = 60 bytes - IPv6: 40 + 8 + 32 = 80 bytes

Functions

func CalculateMTU

func CalculateMTU(pathMTU int, isIPv6 bool, tunnelMode bool) int

CalculateMTU returns the appropriate MTU based on whether we're testing through an existing tunnel or to a WireGuard endpoint.

When tunnelMode is true, the path MTU is returned as-is because the WireGuard overhead is already applied by the tunnel.

When tunnelMode is false, the WireGuard overhead is subtracted to give the optimal MTU setting for a new tunnel.

func CalculateWireGuardMTU

func CalculateWireGuardMTU(pathMTU int, isIPv6 bool) int

CalculateWireGuardMTU calculates the optimal WireGuard interface MTU given the path MTU and IP version

Types

type Discoverer

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

Discoverer handles MTU discovery operations

func NewDiscoverer

func NewDiscoverer(target net.IP, log *output.Logger, minMTU, maxMTU int) *Discoverer

NewDiscoverer creates a new MTU discoverer for the given target

func (*Discoverer) FindPathMTU

func (d *Discoverer) FindPathMTU() (int, error)

FindPathMTU uses binary search to find the path MTU to the target