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Date:      Mon, 28 Apr 1997 18:25:20 -0700 (PDT)
From:      Archie Cobbs <archie@whistle.com>
To:        rohit@cs.umd.edu (Rohit Dube)
Cc:        hackers@freebsd.org
Subject:   Re: Bizzare Ping (and other) bugs.
Message-ID:  <199704290125.SAA17527@bubba.whistle.com>
In-Reply-To: <199704251438.KAA23135@seine.cs.umd.edu> from Rohit Dube at "Apr 25, 97 10:38:38 am"

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> I was wondering if anybody had encountered/solved the following ping bug -
> 
> [1] Change the IP address of an interface (using ifconfig).
> [2] Ping a target machine from that interface. No response.
> [3] Look at the exchange using 'tcpdump'. The ping packets going out
>     of the 'changed' interface have the old address. ICMP echo replies 
>     from the target machine are to this old address and are not delivered
>     to ping.

Yep, we've seen it :-)

> In general FreeBSD/4.4BSD code for changed/downed/deleted interfaces/routes at
> run-time seems to be lacking.

Easier noted than fixed, unfortunately... but maybe someday... Julian E.
has looked at this a good deal.

The problem is that the networking code isn't real good at keeping
track of what's pointing at what other structures, and it can't
completely free old interface addresses since a route in the routing
table may still point to it, etc. That's my level of detail of
understanding anyway.

-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com



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