yeah i should have done this before, i know

session/modules/net_recon.go

@@ -0,0 +1,132 @@
+package session_modules
+
+import (
+	"fmt"
+	"github.com/evilsocket/bettercap/net"
+	"github.com/evilsocket/bettercap/session"
+	"time"
+)
+
+type Discovery struct {
+	session.SessionModule
+
+	refresh int
+	before  net.ArpTable
+	current net.ArpTable
+	quit    chan bool
+}
+
+func NewDiscovery(s *session.Session) *Discovery {
+	d := &Discovery{
+		SessionModule: session.NewSessionModule(s),
+
+		refresh: 1,
+		before:  nil,
+		current: nil,
+		quit:    make(chan bool),
+	}
+
+	d.AddHandler(session.NewModuleHandler("net.recon (on|off)", "^net\\.recon\\s+(on|off)$",
+		"Start/stop network hosts discovery in background.",
+		func(args []string) error {
+			if args[0] == "on" {
+				return d.Start()
+			} else {
+				return d.Stop()
+			}
+		}))
+
+	d.AddHandler(session.NewModuleHandler("net.show", "^net\\.show$",
+		"Show current hosts list.",
+		func(args []string) error {
+			return d.Show()
+		}))
+
+	return d
+}
+
+func (d Discovery) Name() string {
+	return "Network Recon"
+}
+
+func (d Discovery) Description() string {
+	return "Read periodically the ARP cache in order to monitor for new hosts on the network."
+}
+
+func (d Discovery) Author() string {
+	return "Simone Margaritelli <evilsocket@protonmail.com>"
+}
+
+func (d Discovery) OnSessionEnded(s *session.Session) {
+	if d.Running() {
+		d.Stop()
+	}
+}
+
+func (d *Discovery) Start() error {
+	if d.Running() == false {
+		d.SetRunning(true)
+
+		go func() {
+			log.Info("Network discovery started.\n")
+
+			for {
+				select {
+				case <-time.After(time.Duration(d.refresh) * time.Second):
+					var err error
+
+					if d.current, err = net.ArpUpdate(d.Session.Interface.Name()); err != nil {
+						log.Error(err)
+						continue
+					}
+
+					var new net.ArpTable = make(net.ArpTable)
+					var rem net.ArpTable = make(net.ArpTable)
+
+					if d.before != nil {
+						new = net.ArpDiff(d.current, d.before)
+						rem = net.ArpDiff(d.before, d.current)
+					} else {
+						new = d.current
+					}
+
+					if len(new) > 0 || len(rem) > 0 {
+						// refresh target pool
+						for ip, mac := range new {
+							d.Session.Targets.AddIfNotExist(ip, mac)
+						}
+
+						for ip, mac := range rem {
+							d.Session.Targets.Remove(ip, mac)
+						}
+					}
+
+					d.before = d.current
+
+				case <-d.quit:
+					log.Info("Network discovery stopped.\n")
+					return
+				}
+			}
+		}()
+
+		return nil
+	} else {
+		return fmt.Errorf("Network discovery already started.")
+	}
+}
+
+func (d *Discovery) Show() error {
+	d.Session.Targets.Dump()
+	return nil
+}
+
+func (d *Discovery) Stop() error {
+	if d.Running() == true {
+		d.SetRunning(false)
+		d.quit <- true
+		return nil
+	} else {
+		return fmt.Errorf("Network discovery already stopped.")
+	}
+}