** Paul Tansom paul@aptanet.com [2020-01-31 12:59]:
** Chris Green cl@isbd.net [2020-01-30 20:08]:
On Thu, Jan 30, 2020 at 05:40:47PM +0000, Paul Tansom wrote:
** Chris Green cl@isbd.net [2020-01-30 17:22]:
You'd think this was easy but although I can find the information easily enough I can't find a concise way of doing it.
What I want is to get same information for the system I'm logged into as is given by 'arp-scan -lx' for all other systems on the LAN:-
root@t470:~# arp-scan -lx 192.168.1.1 xx:xx:xx:xx:xx:xx DrayTek Corp. 192.168.1.3 xx:xx:xx:xx:xx:xx Fujitsu Technology Solutions GmbH 192.168.1.4 xx:xx:xx:xx:xx:xx Raspberry Pi Foundation 192.168.1.10 xx:xx:xx:xx:xx:xx TP-LINK TECHNOLOGIES CO.,LTD. 192.168.1.20 xx:xx:xx:xx:xx:xx DrayTek Corp. 192.168.1.50 xx:xx:xx:xx:xx:xx Oki Electric Industry Co., Ltd. 192.168.1.96 xx:xx:xx:xx:xx:xx HUMAX Co., Ltd. 192.168.1.98 xx:xx:xx:xx:xx:xx TP-LINK TECHNOLOGIES CO.,LTD. 192.168.1.111 xx:xx:xx:xx:xx:xx TP-LINK TECHNOLOGIES CO.,LTD. 192.168.1.114 xx:xx:xx:xx:xx:xx MICRO-STAR INT'L CO.,LTD 192.168.1.95 xx:xx:xx:xx:xx:xx Sonos, Inc. 192.168.1.104 xx:xx:xx:xx:xx:xx Amazon Technologies Inc.I can get IP address of my current LAN connection using 'hostname -i':-
chris$ hostname -i 192.168.1.92... but I can't find a neat way of getting the corresponding MAC address and company information as for arp-scan. The MAC address can be obtained using ifconfig or ip but it's an exercise in frustration trying to extract the relevant bits:-
chris$ ifconfig enp0s31f6: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 ether c8:5b:76:de:2a:fc txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 16 memory 0xec200000-ec220000 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 639 bytes 279749 (279.7 KB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 639 bytes 279749 (279.7 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.92 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::8239:9067:e11:92be prefixlen 64 scopeid 0x20<link> ether xx:xx:xx:xx:xx:xx txqueuelen 1000 (Ethernet) RX packets 14315 bytes 7281010 (7.2 MB) RX errors 0 dropped 1 overruns 0 frame 0 TX packets 14719 bytes 1911802 (1.9 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0You'd have to first find that the WiFi device wlp4s0 is providing the LAN interface (I want it to work when it's wired with enp0s31f6 when that's in use, can't just hard code wlp4s0) and then go to the 'ether' line to get the MAC address. Even then you don't get the company name. It's possible but hard work and messy, I'd like to find a simple way.
** end quote [Chris Green]
You should be able to get this with:
sudo nmap -sn 192.168.1.0/24
adjusted for your network (that isn't mine, but looks to be the range you are on. If you have a subnet mask wider than 255.255.255.0 you will need to adjust the /24 notation.
Yes, but...
It *doesn't* return the bit I want, the MAC address and company name for the local system, see:-
chris@esprimo$ sudo nmap -sn 192.168.1.0/24 Starting Nmap 7.80 ( https://nmap.org ) at 2020-01-30 20:04 GMT Nmap scan report for 2860n.zbmc.eu (192.168.1.1) Host is up (0.00034s latency). MAC Address: xx:xx:xx:xx:xx:xx (DrayTek) Nmap scan report for newdns.zbmc.eu (192.168.1.4) Host is up (0.00046s latency). MAC Address: xx:xx:xx:xx:xx:xx (Raspberry Pi Foundation) ... ... ... Nmap scan report for onkyoTx-nr616.zbmc.eu (192.168.1.117) Host is up (0.00057s latency). MAC Address: xx:xx:xx:xx:xx:xx (Onkyo) Nmap scan report for S685-IP.zbmc.eu (192.168.1.118) Host is up (0.071s latency). MAC Address: xx:xx:xx:xx:xx:xx (Gigaset Communications GmbH) Nmap scan report for esprimo.zbmc.eu (192.168.1.3) Host is up. Nmap done: 256 IP addresses (15 hosts up) scanned in 1.56 seconds chris@esprimo$No MAC address for esprimo.
** end quote [Chris Green]
Ah, I misunderstood the requirement. I thought you were looking for the MAC addresses of the other hosts on the network. In which case I would try:
ip -o -br link | awk '$0 !~ /lo/ {print $3}'
I'm assuming you only have a single NIC, so...
for the ip command: the -o puts the the output on a single line for each interface to make processing easier the -br uses the brief format with only basic information, which includes the MAC address
for the awk command: the $0 !~ /lo/ excludes the loopback interface from the outhput (which is in the first column) the {print $3} only outputs the third column which has the MAC address in
if you have multiple NICs or interfaces beyond the loopback one you'll get multiple lines
** end quote [Paul Tansom]
With the other solutions posted I couldn't resist trying to come up with an improved variant of the above that just gives the MAC address of the default route:
ip -o -br link show `ip r l default | awk '{print $5}'` | awk {'print $3'}
I've used show to just show a single interface The `` allows me to find the default interface by picking it from a route list and use it as a parameter At which point you don't need to exclude the loopback interface so I can remove that bit
With computers there's always more than one way, and rarely if ever a one size fits all solution.
I was geeky enough to insist on coming up with more solutions for a Prolog problem on a course many years back. I found the solution I had come up with was in a book in the store across the road - just had to prove I hadn't just copied it like everyone else; not to mention the challenge :-)