closes #320 enable LinuxMACFetcher on Linux

CHANGELOG

@@ -1,10 +1,10 @@
 Changes in 3.8.0:
 - Support for Mac M1 (provided that it runs an arm64 build of Java) - thanks to @aplr #284
 - SWT updated for all platforms
-- Java 11 is now the minimum required (due to SWT)
-- Source can be built with Java 17
+- Java 11 is now the minimum required (due to SWT), source can now be built with Java 17
 - If real network netmask is known (e.g. LAN), then skipping of broadcast addresses will respect that instead of always skipping .0 and .255 #309
 - Pressing IP^ button to prefill local network interfaces will now set netmask in Range Feeder
+- LinuxMACFetcher will now read Kernel ARP table directly, not relying on the arp utility to be available #320
 - Mac vendors updated
 
 Changes in 3.7.6:

src/net/azib/ipscan/config/ComponentRegistry.java

@@ -43,7 +43,8 @@ public class ComponentRegistry {
 		i.register(TXTExporter.class, CSVExporter.class, XMLExporter.class, IPListExporter.class);
 
 		i.register(IPFetcher.class, PingFetcher.class, PingTTLFetcher.class, HostnameFetcher.class, PortsFetcher.class);
-		i.register(MACFetcher.class, (MACFetcher) Class.forName(MACFetcher.class.getPackage().getName() + (Platform.WINDOWS ? ".WinMACFetcher" : ".UnixMACFetcher")).newInstance());
+		i.register(MACFetcher.class, (MACFetcher) Class.forName(MACFetcher.class.getPackage().getName() +
+				(Platform.WINDOWS ? ".WinMACFetcher" : Platform.LINUX ? ".LinuxMACFetcher" : ".UnixMACFetcher")).newInstance());
 		i.register(CommentFetcher.class, FilteredPortsFetcher.class, WebDetectFetcher.class, HTTPSenderFetcher.class,
 			NetBIOSInfoFetcher.class, PacketLossFetcher.class, HTTPProxyFetcher.class, MACVendorFetcher.class);
 		i.register(FeederRegistry.class, i.require(FeederGUIRegistry.class));

src/net/azib/ipscan/fetchers/LinuxMACFetcher.java

@@ -28,7 +28,7 @@ public class LinuxMACFetcher extends MACFetcher {
 	@Override public String resolveMAC(InetAddress address) {
 		try {
 			String ip = address.getHostAddress();
-			return arpLines().filter(line -> line.startsWith(ip)).findFirst()
+			return arpLines().filter(line -> line.startsWith(ip + " ")).findFirst()
 				.map(line -> line.substring(macIndex, macIndex + macLength).toUpperCase())
 				.filter(mac -> !unavailableMac.equals(mac))
 				.orElse(getLocalMAC(address));