nanog mailing list archives
Re: Sending ARP request to unicast MAC instead of broadcast MAC address?
From: Steven King <sking () kingrst com>
Date: Thu, 17 Jun 2010 22:14:45 -0400
I believe they call this a Gratuitous ARP Request. It is used automatically when interfaces are brought up to detect IP conflicts. On 6/17/10 5:45 PM, Chris Woodfield wrote:
Looks like all the replies I got were private, so thanks all - to summarize, I got everything from "Read The Fine Kernel Source" to "Read The Fine RFC" to "Read RFC 1122, Section 2.3.2.1, it's quite a Fine read". So for other folks out there like me who obviously can't read RFCs, the answer is "yes". :) -C On Jun 16, 2010, at 3:57 51PM, Chris Woodfield wrote:OK, this sounds Really Wacky (or, Really Hacky if you're into puns) but there's a reason for it, I swear... Will typical OSS UNIX kernels (Linux, BSD, MacOS X, etc) reply to a crafted ARP request that, instead of having FF:FF:FF:FF:FF:FF as its destination MAC address, is instead sent to the already-known unicast MAC address of the host? Next, what would be your utility of choice for crafting such a packet? Or is this something one would need to code up by hand in a lower-level language? Thanks, -C
-- Steve King Senior Linux Engineer - Advance Internet, Inc. Cisco Certified Network Associate CompTIA Linux+ Certified Professional CompTIA A+ Certified Professional
Current thread:
- Sending ARP request to unicast MAC instead of broadcast MAC address? Chris Woodfield (Jun 16)
- Re: Sending ARP request to unicast MAC instead of broadcast MAC address? James Hess (Jun 16)
- Re: Sending ARP request to unicast MAC instead of broadcast MAC address? Ingo Flaschberger (Jun 16)
- Re: Sending ARP request to unicast MAC instead of broadcast MAC address? Crist Clark (Jun 17)
- Re: Sending ARP request to unicast MAC instead of broadcast MAC address? Chris Woodfield (Jun 17)
- Re: Sending ARP request to unicast MAC instead of broadcast MAC address? Steven King (Jun 17)