10-24-2012
Quote:
Often you can ping the broadcast address and the duplicate IP addresses will show up in the reply.
There's absolutely nothing on my network that answers a ping broadcast -- perhaps because of the wireless bridge -- and increasingly many things these days never bother answering ping at all.
Engineers seem to be forgetting why ICMP exists. I don't like it, but if the equipment isn't my own, I have to live with it.
Equipment can't block or ignore ARP and still function on a local network though, so I've got the
arping tool installed standard everywhere. That's how I tracked down the dup.
arping2 -d -i lan 192.168.6.101 Note that without the -d, it won't show dups.
Last edited by Corona688; 10-24-2012 at 12:38 PM..
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ping(8) System Manager's Manual ping(8)
Name
ping - send ICMP ECHO_REQUEST packets to network hosts
Syntax
/etc/ping [ options ] host [ datasize [ npackets ]]
Description
The DARPA Internet is a large and complex network of hardware connected together by gateways. The command utilizes the ICMP protocol's
mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams (pings) have an IP and ICMP
header, followed by a struct timeval, and then an arbitrary number of pad bytes used to fill out the packet. The length of the default
datagram 64 bytes, but this may be changed using the command-line option.
Typing ``ping host'' without any options will either report ``host is alive'' or ``no answer from host''. To get more statistics use the
-l option or one of the other options.
When using for fault isolation, it should first be run on the local host to verify that the local network interface is up and running.
Then, hosts and gateways further and further away should be pinged. The command with options sends one datagram per second and prints one
line of output for every ECHO_RESPONSE returned. No output is produced if there is no response. If an optional npackets is given, only
that number of requests is sent. Round-trip times and packet loss statistics are computed. When all responses have been received or the
program times out with npackets specified, or if the program is terminated with a SIGINT, a brief summary is displayed.
Options
-d Turns on SO_DEBUG flag on the socket.
-l Gives more statistics than if is used without options. Long output.
-r Bypasses the normal routing tables and sends directly to a host on an attached network. If the host is not on a directly-attached
network, an error is returned. This option can be used to ping a local host through an interface that has no route through it. For
example, after the interface was dropped by
-v Lists ICMP packets other than ECHO RESPONSE that are received. Verbose output.
Restrictions
This program is intended for use in network testing, measurement, and management. It should be used primarily for manual fault isolation.
Because of the load it could impose on the network, it is unwise to use during normal operations or from automated scripts.
See Also
netstat(1), ifconfig(8c)
ping(8)