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Date:      Fri, 25 Apr 1997 10:38:38 -0400
From:      Rohit Dube <rohit@cs.umd.edu>
To:        hackers@freebsd.org
Cc:        rohit@cs.umd.edu
Subject:   Bizzare Ping (and other) bugs.
Message-ID:  <199704251438.KAA23135@seine.cs.umd.edu>

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Hi,

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.

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

For example kern/425 from GNATS (May 16, 1995) still exists - 
Downing and deleting an interface doesnot get rid of the arp and the routing
entry still exists. 
Similarly changing the IP address of an interface doesnot get rid of the
ip-mac association for the old interface.

I would appreciate notes/fixes/feedback from anybody who has seen or solved 
problems related to run-time interface changes.

Thanks in advance.

--rohit.

PS: I use FreeBSD 2.2-961006-SNAP, but I think this bug has been around for 
    quite a few previous and later releases/snaps.



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