How can I store the MAC address of a client in a file before redirecting to any port using iptables/ebtables

Question

I want to store the MAC address of the client to a file before redirecting to some IP or port. I'm doing the redirection using iptables. Is it possible to get the MAC of the client and store it in a file?

Answer 1

Yes, it's possible to get the MAC address of the client and store it in a file. You need to change your network driver to perform this when it parses packet from the client. The MAC address belongs to Layer 2 of the of the OSI network model, thus it can be extracted before passing it to Layer 3, which handles the IP.