gateway

A simple library for discovering the IP address of the default gateway.

Example:

package main

import (
    "fmt"

    "github.com/jackpal/gateway"
)

func main() {
    gateway, err := gateway.DiscoverGateway()
    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println("Gateway:", gateway.String())
   }
}

Provides implementations for:

Darwin (macOS)
Dragonfly
FreeBSD
Linux
NetBSD
OpenBSD
Solaris and illumos
Windows

Other platforms use an implementation that always returns an error.

Pull requests for other OSs happily considered!

Versions

v1.0.15

Update dependencies to latest versions. This was done to squelch a github security alert caused by depending upon an old version of x/net. This is the first time I've updated module versions, the tests pass, so hopefully everything's good.

v1.0.14

Fix panic when interface not set in Solaris netstat -rn output.

v1.0.13

Add tools/check-cross-compile.sh to check that the code compiles for various OSs.
Fix compilation errors exposed by tools/check-cross-compile.sh.

v1.0.12

If there are multiple default gateways, Windows now returns the gateway with the lowest metric.
Fix solaris build break. (In theory, IDK how to test this easily.)
Upgrade to golang 1.21
Upgrade golang.org/x/net version, makes dependabot happy. Probably was not any actual security issue because gateway doesn't use any of the APIs of golang.org/x/net that had security issues.

v1.0.11

Implement DiscoverInterface for BSD-like OSes.

v1.0.10

Fix non-BSD-based builds.

v1.0.9

Add go.mod and go.sum files.
Use "golang.org/x/net/route" to implement all BSD variants.
- As a side effect this adds support for Dragonfly and NetBSD.
Add example to README.
Remove broken continuous integration.

v1.0.8

Add support for OpenBSD
Linux parser now supports gateways with an IP address of 0.0.0.0
Fall back to netstat on darwin systems if route fails.
Simplify Linux /proc/net/route parsers.

jackpal / gateway

readme