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Date: Mon, 22 Jan 1996 23:14:09 -0800 (PST)
From: Bill Fenner <fenner>
Message-Id: <199601230714.XAA07552@freefall.freebsd.org>
To: hackers@freebsd.org, wollman@freebsd.org
Subject: arp(8) and proxy arp's
Cc: fenner
Sender: owner-hackers@freebsd.org
Precedence: bulk

There have been some troubles reported recently with respect to partially
completed arp entries making things confusing with dynamic ppp sessions.
I'd like to propose a chance to the user-level arp program to try to
reduce the potential confusion.

The existing arp(8) can produce two different types of arp entries when
you say "arp -s ip ether pub", depending on whether or not a host route
for ip is already in the routing table.  This behavior is silent and
potentially confusing and deadly.

I propose to seperate out "pub" (announce this ARP entry to others, use
this ARP entry when trying to talk to this host) and "proxy" (only
announce this ARP entry and don't try to use it) to make it deterministic
which one the arp(8) command creates.  I plan to add a "Do-What-I-Mean"
that recognizes "arp -s ip myetheraddress pub" and turns it into a
"proxy" request.  But "pub" will create a "proxy-and-use" entry and
"proxy" will create a "proxy only" entry and the behavior will always
be predictable no matter what is in the routing table.

Comments?  Given the DWIM, I don't think that anyone will even notice
this change, other than that they won't be able to create confusing
arp table entries any more.

  Bill