![]() It’s probably not an effective way to quickly map a subnet in everyday life. To return to the original claim that a broadcast ping will reveal all devices in a given subnet: the conclusion is that this only goes for network devices, and not for end devices. So with limited testing I can conclude for now that it’s also just network devices that respond to ping in IPv6. But the test results are similar to IPv4: a ping to FF02::1 (‘all nodes’ multicast) does not give a single reply, but a ping to FF02::2 (‘all routers’ multicast) gives a reply from the Vyatta, which is indeed configured for IPv6 routing. Since most of my devices do not have IPv6 support for the moment (I’m planning on upgrading them in the future), I’m left with the Vyatta, Windows 7, Windows Server, and Fedora for this test. Note that I say multicast, as IPv6 has no concept of broadcast. Multicast pings would be the only feasible option to scan a subnet. A common /64 subnet is 1.8×10^19 addresses, with EUI-64 (see a perfect explanation about EUI-64 on ) you can exclude some addresses, leaving ‘just’ 2.8×10^14 possible combinations. That answers one question, but what about IPv6? Are things different there? A ping sweep is nearly impossible. So after a ping sweep, just doing ‘arp -a’ in the Windows command line reveals all managed network devices. There’s still a difference between a ping sweep and a broadcast ping, even if just done towards network devices: a ping sweep will trigger ARP requests for each address, to which devices will respond if they have the address, whether ICMP pings are blocked or not. To be sure I didn’t make a mistake, I did unicast pings after this to the addresses that didn’t respond, and they all reacted fine. The Vyatta and the ISP gateway are also network devices, but I have no control over the gateway, and the Vyatta is actually nothing more than a stripped-down Linux and thus may react as an end device in this regard. All other devices wouldn’t respond to broadcast pings. The results showed a clear separation between network devices and end devices: the Cisco gear (with the exception of the IP Phone) would respond to broadcast pings, as well as the DD-WRT. I did several tests and also changed IP addresses several times between tests to ensure ARPs were sent around the network, which made it easier to follow the captures on Wireshark. All devices received an IP address in the 192.168.0.0/24 range, the pings were done to 192.168.0.255. Contrary to Windows, IOS will list all replies received when sending to a broadcast address. I also did pings from some of the Cisco devices. I ran Wireshark on the physical machines (Windows 7 and Windows XP) from which I was going to originate the pings. – And finally, one iPod, for a total of 12 devices having an IP address. – The ISP-provided gateway: a Motorola with NAT I created a subnet with as many different devices as I could get my hand on at the time. ![]() I decided to test this out for myself and see what happened. A ping sweep is easiest, but some people claim that a simple ping to the subnet broadcast address will make all devices respond. Sending 230, -byte ICMP Echos to 10.178.0.I’ve often seen discussions of ‘how to find devices in the network using pings’. Loose, Strict, Record, Timestamp, Verbose: You can do something similar with extended ping, e.g.: Enter ping and question mark to see if those additional options are offered. However, the later IOSs also offer some of those options on the command line, size being one of them. entering ping followed by an enter, will prompt you for various options including size (also offers a range of size too). In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.Īs the other posters have already noted, extended ping, i.e. Usage of this posting's information is solely at reader's own risk. ![]() Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. A ping sweep (also known as an ICMP sweep) is a basic network scanning technique used to determine which of a range of IP addresses map to live hosts (computers).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |