multiple entries using ‘arp-scan’ but not reflected in ‘arp’ command

[Undareth]

To expand, I get multiple arp entries when conducting the ‘arp-scan’ command on my eth0 interface for my router.

However none of these entries are seen when using ‘arp’. I've transcribed a rough example from my ssh session.

arp-scan - I eth0 -l
Results(Ive fudged the network IDs, The Host IDs are correct):
123.244.255.128  
123.244.255.129
123.244.255.130
123.244.255.132
123.244.255.133
123.244.255.134
123.244.255.135

arp -i eth0
123.244.255.129

Router model is RTAC86U. To add, none of these entries are my router's actual host id (Host id is 123.244.255.131)

 

[torch]

Two different functions that you can read from their respective man pages:

arp-scan sends ARP packets to hosts on the local network... https://linux.die.net/man/1/arp-scan
Arp manipulates or displays the kernel's IPv4 network neighbour cache. https://www.man7.org/linux/man-pages/man8/arp.8.html

 

[Undareth]

Two different functions that you can read from their respective man pages:

arp-scan sends ARP packets to hosts on the local network... https://linux.die.net/man/1/arp-scan
Arp manipulates or displays the kernel's IPv4 network neighbour cache. https://www.man7.org/linux/man-pages/man8/arp.8.html

Would this mean there are other hosts on that interface's network*,if looking at the arp-scan output. If so, is this something to be concerned about (duplicate hosts being generated or something to that effect).

 

[ColinTaylor]

Without seeing the real data I can't be sure. But I suspect this could be the proxy-arp situation described in the documentation. I see it on my gateway network:

xxx.4.152.1      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.2      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.3      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.4      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.5      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.6      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.7      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.8      00:01:5c:7a:fa:47       CADANT INC.
xxx.4.152.9      00:01:5c:7a:fa:47       CADANT INC.