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Date:      Tue, 27 Jun 2000 19:20:46 -0400
From:      Brian Reichert <reichert@numachi.com>
To:        freebsd-net@freebsd.org
Subject:   Did IP aliasing change after 2.x?
Message-ID:  <20000627192045.J1800@numachi.com>

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I must be missing something, so please bear with me.

I have two servers running.

  198.175.254.7 is running 2.2.7-RELEASE.
  198.175.254.4 is running 4.0-RELEASE.

In each case, the IP is an alias on the NIC.

From within my net, I can ping each of these name servers.  From
outside of my net, I can only ping 198.175.254.7, the 'old' box.

I can get to their primary IP addresses just fine.

There is no packet filtering at play here.

On each of the newer box, when I dump ping traffic with
tcpdump:

  # tcpdump -n host 198.175.254.4 
  tcpdump: listening on dc0
  19:05:21.437187 208.176.83.163 > 198.175.254.4: icmp: echo request
  19:05:22.434743 208.176.83.163 > 198.175.254.4: icmp: echo request
  19:05:23.431832 208.176.83.163 > 198.175.254.4: icmp: echo request

That network segment is getting packets destined for 198.175.254.4,
but the card never generates the 'echo reply' packets.

The 2.2.7-RELEASE box:

  # ifconfig ed1
  ed1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 198.175.254.2 netmask 0xffffff00 broadcast 198.175.254.255
        inet 198.175.254.7 netmask 0xffffffff broadcast 198.175.254.7
        ether 00:40:05:4c:5c:e0

The 4.0-RELEASE box:

  # ifconfig dc0
  dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 198.175.254.6 netmask 0xffffff00 broadcast 198.175.254.255
        inet6 fe80::220:78ff:fee1:4ae1%dc0 prefixlen 64 scopeid 0x1
        inet 198.175.254.4 netmask 0xffffffff broadcast 198.175.254.4
        ether 00:20:78:e1:4a:e1
        media: autoselect (10baseT/UTP) status: active
        supported media: autoselect 100baseTX <full-duplex> 100baseTX
        10baseT/UTP <full-duplex> 10baseT/UTP 100baseTX <hw-loopback> none

The mailing list archives mentioned affixing the alias to lo0,
rather than the NIC; I tried that, to no effect.  There was nothing
on the errata page.

Any ideas on why I might be seeing different results here?

-- 
Brian 'you Bastard' Reichert		reichert@numachi.com
37 Crystal Ave. #303			Daytime number: (603) 434-6842
Derry NH 03038-1713 USA			Intel architecture: the left-hand path


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