I have a device running Debian Linux (Buster) that is connected to a neighbor device via a VLAN interface. The neighbor is sending ICMP echo replies to my device through that VLAN interface, but the Linux device is NOT sending ICMP echo requests. Is it possible (with some configuration tweaking) for the Linux device to learn the MAC address of the neighbor from these ICMP messages and create entries for them in the neighbor table (
ip -4 neigh show), using some built-in Linux configuration settings?
Edit: The neighbor device is not sending any ARP/GARP packets to the Linux device, and I am not able to configure it to do so.
I have included abbreviated
ip addr show output here, with more info:
284: Ethernet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9100 qdisc pfifo_fast master Bridge state UP group default qlen 1000 link/ether 94:8e:d3:04:eb:28 brd ff:ff:ff:ff:ff:ff inet6 fe80::968e:d3ff:fe04:eb28/64 scope link valid_lft forever preferred_lft forever 279: Vlan1000@Bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9100 qdisc noqueue state UP group default qlen 1000 link/ether 00:aa:bb:cc:dd:ee brd ff:ff:ff:ff:ff:ff inet 192.168.0.1/21 brd 192.168.7.255 scope global Vlan1000 valid_lft forever preferred_lft forever inet6 fc02:1000::1/64 scope global valid_lft forever preferred_lft forever inet6 fe80::2aa:bbff:fecc:ddee/64 scope link valid_lft forever preferred_lft forever
The ICMP echo replies are being sent to
Vlan1000 (the destination MAC is the VLAN's MAC address).
Vlan1000 shows the ICMP echo replies, and I am able to see the neighbor MAC as the destination MAC. Is there someway to automatically learn the neighbor MAC in the ARP table?