Arp-scan

I was almost reinventing the wheel looking for CPAN modules until I finally found arp-scan.

% sudo arp-scan --interface=eth0 192.168.0.0/24
Interface: eth0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.8.1 with 256 hosts (http://www.nta-monitor.com/tools/arp-scan/)
192.168.0.1     00:0d:02:00:00:00	NEC AccessTechnica, Ltd.
192.168.0.193	44:37:e6:00:00:00	Hon Hai Precision Ind.Co.Ltd
192.168.0.194	c0:ff:d4:00:00:00	(Unknown)
192.168.0.198	bc:5f:f4:00:00:00	ASRock Incorporation
192.168.0.199	00:25:dc:00:00:00	Sumitomo Electric Networks, Inc
192.168.0.210	a4:12:42:00:00:00	(Unknown)
192.168.0.211	00:3a:9d:00:00:00	NEC AccessTechnica, Ltd.

7 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.8.1: 256 hosts scanned in 1.387 seconds (184.57 hosts/sec). 7 responded

This exactly what I wanted.

arp-scan

It seems that he does not know “c0:ff:d4”, Netgear, and “a4:12:42”, NecPlatf, but it’s OK. (Note: NEC Platforms (2014~) and NEC Access Technica (~2014) are the same company.)

Ping and Arp script

There should be better ways, but this will do for the moment.

#!/bin/bash
for ipadr in 192.168.0.{1..254}
do
 ping -c 1 -w 1 $ipadr
done
arp -n | sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4 | grep ether
% ./ping.sh
192.168.0.1    ether   00:0d:02:xx:xx:xx   C  eth0
192.168.0.193  ether   50:7e:5d:xx:xx:xx   C  eth0
192.168.0.196  ether   c0:ff:d4:xx:xx:xx   C  eth0

pingsh

Port Mirroring (2)

mirroring

The Port 1 goes to the DHCP server (NecPlatf_something), and the Port 2 goes to the AP, through which a DHCP client(Fujitus_something) is connected. The PC to capture the packets is connected to the Port 5.

mirroring3

So, why does he have to repeat the same question after he seems to have gotten the answer?

DHCP and ARP

arpdhcp

This is when there appears an error message on the DHCP client, Fujitsu_something, that says acquiring an IP address has failed.

NecPlatf_something is the DHCP server at 192.168.0.1.

The message disappears within a second, and the device will become IP reachable at 192.168.0.195.

% arp -n
Address                  HWtype  HWaddress           Flags Mask            Iface
192.168.0.195            ether   2c:d4:44:00:00:00   C                     eth0

% ping 192.168.0.195
PING 192.168.0.195 (192.168.0.195) 56(84) bytes of data.
64 bytes from 192.168.0.195: icmp_seq=1 ttl=64 time=31.8 ms

Beamforming

index_img_key

As an operator using only wire antennas, a beam antenna is always something to adore. Here is an 802.11ac compliant access point with beamforming technology.

beamforming

Unfortunately, your receiver (a beamformee) must also be capable of responding to the channel calibration procedure, called channel sounding, initiated by the AP (a beamformer) to activate the feature.

In ’80s when I got my first license, I did not expect such proliferation of wireless equipment, such as mobile phones and Wi-Fi devices. Another thing which I did not anticipated to emerge is MIMO.

mimo

And now they are even talking about Multi-user MIMO, which you may be tempted to adopt when contesting or dealing with pile-ups.

80211ac

This is a nice on-line book to learn 802.11ac related technologies, and the above figures 4-5 and 4-14 are in Chapter 4: Beamforming in 802.11ac.

http://chimera.labs.oreilly.com/books/1234000001739

Octcat

Octocat

Now I can push and pull with Eclipse using SSH, but with an unwanted src subdirectory.

pushpull

Please click the Octcat to visit my repositories, such as gtkmm branch:test1.