What Moves on the Wire

IP does not travel alone. Ethernet wraps it in a frame with a 14-byte header. See the envelope, decode the addresses, watch ARP ask its question.

Labs in this module

Watching Traffic - tshark and tcpdump let you see every packet that crosses your interface. This is where networking becomes real.
The Ethernet Frame - One packet, fully dissected. Ethernet header wraps IP wraps ICMP. Envelopes inside envelopes.
MAC Addresses - MAC addresses identify network hardware. The MAC sublayer stamps them into every frame. This lesson teaches both, and clears up the confusio
EtherType - EtherType is the 2-byte tag in every Ethernet frame that tells the kernel which protocol is inside. One wire, multiple protocols, one tag to
ARP - ARP answers one question: "I know your IP, what is your MAC?" Watch it happen from scratch. See every field. Flush the cache and trigger it
Building a Bridge - A Linux bridge is a software switch. Three hosts are already plugged into one. Watch it learn MAC addresses, read its forwarding database, a