Module 04
ARP
The glue between IP addresses and MAC addresses. Broadcast a request, fill the cache, let entries expire, then see how a forged reply can redirect traffic.
Start lesson 1
Who has this address? · 7 min · free, no account
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What you'll operate
- Who has this IP address?
- The ARP cache and its timers
- Gratuitous ARP and spoofing
- lessons
- 6
- minutes
- 49
Lessons in this module
- 1Who has this address?Watch a laptop find a printer's MAC address with ARP, and see who learns what.Free, no account7 min
- 2What is inside an ARP message?Read all nine fields of an ARP message, then build a request and pick out a reply yourself.Plus8 min
- 3How long does the cache remember?Watch cache entries get created, refreshed and expired, and see what a stale one does to traffic.Plus8 min
- 4Whose MAC address goes on the frame?Follow one packet across two routers: the frame is re-addressed on every link, and the IP addresses stay the same.Plus9 min
- 5Is this address already taken?Play an ARP probe and an ARP announcement, and see how a device finds and handles a duplicate address.Plus8 min
- 6How does a forged reply redirect traffic?Poison a cache, read the signs it leaves, and see what static entries, switch inspection and proxy ARP each do.Plus9 min
Lesson 1 is open to everyone, with no account. The other lessons in this module are part of Plus.