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// Command arpc provides a simple ARP client which can be used to retrieve
// hardware addresses of other machines in a LAN using their IPv4 address.
package main
import (
"flag"
"fmt"
"log"
"net"
"time"
"github.com/mdlayher/arp"
)
var (
// durFlag is used to set a timeout for an ARP request
durFlag = flag.Duration("d", 1*time.Second, "timeout for ARP request")
// ifaceFlag is used to set a network interface for ARP requests
ifaceFlag = flag.String("i", "eth0", "network interface to use for ARP request")
// ipFlag is used to set an IPv4 address destination for an ARP request
ipFlag = flag.String("ip", "", "IPv4 address destination for ARP request")
)
func main() {
flag.Parse()
// Ensure valid network interface
ifi, err := net.InterfaceByName(*ifaceFlag)
if err != nil {
log.Fatal(err)
}
// Set up ARP client with socket
c, err := arp.Dial(ifi)
if err != nil {
log.Fatal(err)
}
defer c.Close()
// Set request deadline from flag
if err := c.SetDeadline(time.Now().Add(*durFlag)); err != nil {
log.Fatal(err)
}
// Request hardware address for IP address
ip := net.ParseIP(*ipFlag).To4()
mac, err := c.Resolve(ip)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s -> %s", ip, mac)
}
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