initial commit

README.md

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+# Regela ARP proxy
+
+### Very simple, lazy method to configure arp tables
+#### Written for our Virtuozzo's Community OS servers by Elizar [@Regela](https://sources.krechet.tech/Regela)
+
+#### Include example config file in .yml, where is:
+- name: *interfacename*
+- addresses: *list of ips on interfacename*
+
+#### Usage: move config.yum in folder /etc/RegelaArpProxy/ and run binary
+
+```
+~#  RegelaArpProxy --help
+Usage of RegelaArpProxy:
+  -example
+  -i string
+    	Config File (default "/etc/RegelaArpProxy/config.yml")
+
+ ~#  RegelaArpProxy -example
+interfaces:
+- name: br0
+  addresses:
+  - 10.10.100.10
+  - 10.10.100.11
+  - 10.10.100.12
+  - 10.10.100.13
+- name: br1
+  addresses:
+  - 10.10.101.10
+  - 10.10.101.11
+  - 10.10.101.12
+  - 10.10.101.13
+```

config.yml

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+interfaces:
+- name: vlan101
+  addresses:
+  - 10.10.3.2
+  - 10.10.3.5
+- name: vlan102
+  addresses:
+  - 10.10.116.11

src/main.go

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+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"github.com/goccy/go-yaml"
+	"github.com/mdlayher/arp"
+	"github.com/mdlayher/ethernet"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"time"
+)
+
+type Interface struct{
+	Name      string
+	Addresses []net.IP
+}
+
+type Settings struct {
+	Interfaces []Interface
+}
+
+
+var (
+	configFile = flag.String("i", "/etc/RegelaArpProxy/config.yml", "Config File")
+	printExampleFlag = flag.Bool("example",false,"")
+
+
+)
+
+func task(iface Interface){
+	ifi, err := net.InterfaceByName(iface.Name)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	client, err := arp.Dial(ifi)
+	if err != nil {
+		log.Fatalf("couldn't create ARP client: %s", err)
+	}
+
+	// Handle ARP requests bound for designated IPv4 address, using proxy ARP
+	// to indicate that the address belongs to this machine
+	for {
+		pkt, eth, err := client.Read()
+		if err != nil {
+			if err == io.EOF {
+				log.Println("EOF")
+				break
+			}
+			log.Fatalf("error processing ARP requests: %s", err)
+		}
+
+		// Ignore ARP replies
+		if pkt.Operation != arp.OperationRequest {
+			continue
+		}
+
+		// Ignore ARP requests which are not broadcast or bound directly for
+		// this machine
+		if !bytes.Equal(eth.Destination, ethernet.Broadcast) /*&& !bytes.Equal(eth.Destination, ifi.HardwareAddr)*/ {
+			continue
+		}
+
+		log.Printf("request: who-has %s?  tell %s (%s)", pkt.TargetIP, pkt.SenderIP, pkt.SenderHardwareAddr)
+
+		// Ignore ARP requests which do not indicate the target IP
+		for _, ip := range iface.Addresses {
+			if pkt.TargetIP.Equal(ip) {
+				log.Printf("  reply: %s is-at %s", ip, ifi.HardwareAddr)
+				if err := client.Reply(pkt, ifi.HardwareAddr, ip); err != nil {
+					log.Fatal(err)
+				}
+			}
+		}
+	}
+}
+
+
+func printExample()  {
+	settings := Settings{
+		Interfaces: []Interface{
+			{
+				Name: "br0",
+				Addresses: []net.IP{
+					net.ParseIP("10.10.100.10"),
+					net.ParseIP("10.10.100.11"),
+					net.ParseIP("10.10.100.12"),
+					net.ParseIP("10.10.100.13"),
+				},
+			},
+			{
+				Name: "br1",
+				Addresses: []net.IP{
+					net.ParseIP("10.10.101.10"),
+					net.ParseIP("10.10.101.11"),
+					net.ParseIP("10.10.101.12"),
+					net.ParseIP("10.10.101.13"),
+				},
+			},
+		},
+	}
+	out, _ := yaml.Marshal(settings)
+	fmt.Printf("%s",out)
+}
+
+func main() {
+	flag.Parse()
+
+	if *printExampleFlag{
+		printExample()
+		os.Exit(0)
+	}
+
+	cf, err := ioutil.ReadFile(*configFile)
+	if err != nil {
+		log.Fatalf("Read configuration error: %s", err.Error())
+	}
+
+	settings := Settings{}
+	err = yaml.Unmarshal(cf,&settings)
+	for _, iface := range settings.Interfaces {
+		go task(iface)
+	}
+	for {
+		time.Sleep(time.Hour)
+	}
+
+	// Ensure valid interface and IPv4 address
+
+}