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Date:      Thu, 28 Feb 2002 11:20:55 -0500
From:      "David A. Koran" <dak@solo.net>
To:        freebsd-stable@freebsd.org
Subject:   Fwd: Re: ifconfig aliases
Message-ID:  <p05100304b8a409508f5c@[192.168.200.104]>

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>Date: Thu, 28 Feb 2002 11:14:45 -0500
>To: cjclark@alum.mit.edu
>From: "David A. Koran" <dak@solo.net>
>Subject: Re: ifconfig aliases
>Cc:
>Bcc:
>X-Attachments:
>
>>On Wed, Feb 27, 2002 at 07:48:11PM -0800, Michael Sierchio wrote:
>>>  Crist J. Clark wrote:
>>>
>>  > >>ifconfig_fxp0="inet AAA.BBB.CCC.190  netmask 255.255.255.128"
>>>  >>ifconfig_fxp0_alias0="inet AAA. BBB.DDD.209 netmask 255.255.255.248"
>>>  >>ifconfig_fxp0_alias1="inet AAA. BBB.DDD.210 netmask 255.255.255.248"
>>>  >>ifconfig_fxp0_alias2="inet AAA. BBB.DDD.211 netmask 255.255.255.248"
>>>  >>ifconfig_fxp0_alias3="inet AAA. BBB.DDD.212 netmask 255.255.255.248"
>>>  >>ifconfig_fxp0_alias4="inet AAA. BBB.DDD.213 netmask 255.255.255.248"
>>  > >>ifconfig_fxp0_alias5="inet AAA. BBB.DDD.214 netmask 255.255.255.248"
>>>  >>
>>>  >
>>>  > This was never "legal." It has always been a
>>>  > misconfiguration. However, depending on what you were doing, it may
>>>  > still have worked in spite of not making any sense.
>>>
>>>  Care to expand a little bit?
>>
>>Looking at this more... it's a little weird. This machine has all of
>>the addresses on this AAA.BBB.DDD.208/29 subnet? If you are using this
>>as I imagine you are, perhaps putting them on the loopback device
>>would be better.
>
>The scenario is as such. My ISP gives each machine you "lease" an IP 
>address on the network AAA.BBB.CCC.YYY. For "extra" IPs for any of 
>the machines you lease, they give you a block on AAA. BBB.DDD.ZZZ. 
>The mask for my block of extra IPs was 255.255.255.248. (I've also 
>done this config on ed0 and xl0 devices besides the fxp0). And as I 
>mentioned in my previous response, this configuration has worked for 
>a number of years, of which it just stopped working yesterday when I 
>brought this topic up. All the aliased addresses are on the /29 but 
>the base address is on another subnet entirely, go fig.
>
>>
>>The most obvious question that arises when you want to reach another
>>system on the same subnet as the aliases. Which address should be the
>>source?
>
>Actually I can HTTP, SSH, and any other TCP/IP protocol to get to 
>another box (another FreeBSD with a similar config, aliases and all) 
>via any of those addresses on that interface.
>
>
>
>>Depending on how the code works, (1) you might get predictable
>>behavior (it's always the first alias), (2) unpredictable behavior (it
>>might be any one of them), or (3) broken behavior (it doesn't work at
>>all or only works sometimes). It looks like you are seeing (3) at the
>>moment.
>
>I'm betting it was broken behaviour that was mysteriously fixed.. 
>and thus, I had to "clean" my config. (BTW, the NAT and Firewall 
>instructions at FreeBSDDiary.org also list this way of aliasing 
>interfaces, so I'm to wonder where the bad info may have started... 
>maybe a kludge that worked for ages...)
>
>
>>--
>>Crist J. Clark                     |     cjclark@alum.mit.edu
>>                                    |     cjclark@jhu.edu
>>http://people.freebsd.org/~cjc/    |     cjc@freebsd.org
>
>
>--
>
>David A. Koran
>(dak@solo.net) - http://www.solo.net/~dak/
>
>PGP Key ID: 0x8AC39F65
>
>-----BEGIN GEEK CODE BLOCK-----
>Version: 3.1
>GIT/CS/SS d- s+: a- C+++$ UBLHSX++++$ P+++$ L- E--- W+++ N- o-- K-?
>w--- O- M+++$ V-- PS++ PE- Y+>++ PGP t--@ 5 X+ R- tv b+ DI++++ D G
>e*>+++ h++ r y+
>------END GEEK CODE BLOCK------


-- 
David A. Koran
(dak@solo.net) - http://www.solo.net/~dak/

PGP Key ID: 0x8AC39F65

-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GIT/CS/SS d- s+: a- C+++$ UBLHSX++++$ P+++$ L- E--- W+++ N- o-- K-?
w--- O- M+++$ V-- PS++ PE- Y+>++ PGP t--@ 5 X+ R- tv b+ DI++++ D G
e*>+++ h++ r y+
------END GEEK CODE BLOCK------
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<html><head><style type="text/css"><!--
blockquote, dl, ul, ol, li { padding-top: 0 ; padding-bottom: 0 }
 --></style><title>Fwd: Re: ifconfig aliases</title></head><body>
<blockquote type="cite" cite>Date: Thu, 28 Feb 2002 11:14:45 -0500<br>
To: cjclark@alum.mit.edu<br>
From: &quot;David A. Koran&quot; &lt;dak@solo.net&gt;<br>
Subject: Re: ifconfig aliases<br>
Cc:<br>
Bcc:<br>
X-Attachments:<br>
<blockquote type="cite" cite>On Wed, Feb 27, 2002 at 07:48:11PM -0800,
Michael Sierchio wrote:<br>
&gt; Crist J. Clark wrote:<br>
&gt;</blockquote>
<blockquote type="cite" cite>&gt; &gt;&gt;ifconfig_fxp0=&quot;inet
AAA.BBB.CCC.190&nbsp; netmask 255.255.255.128&quot;<br>
&gt; &gt;&gt;ifconfig_fxp0_alias0=&quot;inet AAA. BBB.DDD.209 netmask
255.255.255.248&quot;<br>
&gt; &gt;&gt;ifconfig_fxp0_alias1=&quot;inet AAA. BBB.DDD.210 netmask
255.255.255.248&quot;<br>
&gt; &gt;&gt;ifconfig_fxp0_alias2=&quot;inet AAA. BBB.DDD.211 netmask
255.255.255.248&quot;<br>
&gt; &gt;&gt;ifconfig_fxp0_alias3=&quot;inet AAA. BBB.DDD.212 netmask
255.255.255.248&quot;<br>
&gt; &gt;&gt;ifconfig_fxp0_alias4=&quot;inet AAA. BBB.DDD.213 netmask
255.255.255.248&quot;</blockquote>
<blockquote type="cite" cite>&gt;
&gt;&gt;ifconfig_fxp0_alias5=&quot;inet AAA. BBB.DDD.214 netmask
255.255.255.248&quot;<br>
&gt; &gt;&gt;<br>
&gt; &gt;<br>
&gt; &gt; This was never &quot;legal.&quot; It has always been a<br>
&gt; &gt; misconfiguration. However, depending on what you were doing,
it may<br>
&gt; &gt; still have worked in spite of not making any sense.<br>
&gt;<br>
&gt; Care to expand a little bit?<br>
<br>
Looking at this more... it's a little weird. This machine has all
of<br>
the addresses on this AAA.BBB.DDD.208/29 subnet? If you are using
this<br>
as I imagine you are, perhaps putting them on the loopback device<br>
would be better.</blockquote>
</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>The scenario is as such. My ISP gives
each machine you &quot;lease&quot; an IP address on the network
AAA.BBB.CCC.YYY. For &quot;extra&quot; IPs for any of the machines you
lease, they give you a block on AAA. BBB.DDD.ZZZ. The mask for my
block of extra IPs was 255.255.255.248. (I've also done this config on
ed0 and xl0 devices besides the fxp0). And as I mentioned in my
previous response, this configuration has worked for a number of
years, of which it just stopped working yesterday when I brought this
topic up. All the aliased addresses are on the /29 but the base
address is on another subnet entirely, go fig.</blockquote>
<blockquote type="cite" cite><br>
<blockquote type="cite" cite><br>
The most obvious question that arises when you want to reach
another<br>
system on the same subnet as the aliases. Which address should be
the<br>
source?</blockquote>
</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>Actually I can HTTP, SSH, and any other
TCP/IP protocol to get to another box (another FreeBSD with a similar
config, aliases and all) via any of those addresses on that
interface.</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><br>
<br>
<blockquote type="cite" cite>Depending on how the code works, (1) you
might get predictable<br>
behavior (it's always the first alias), (2) unpredictable behavior
(it<br>
might be any one of them), or (3) broken behavior (it doesn't work
at<br>
all or only works sometimes). It looks like you are seeing (3) at
the<br>
moment.</blockquote>
</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>I'm betting it was broken behaviour that
was mysteriously fixed.. and thus, I had to &quot;clean&quot; my
config. (BTW, the NAT and Firewall instructions at FreeBSDDiary.org
also list this way of aliasing interfaces, so I'm to wonder where the
bad info may have started... maybe a kludge that worked for
ages...)</blockquote>
<blockquote type="cite" cite><br>
<br>
<blockquote type="cite" cite>--<br>
Crist J.
Clark&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span
></span>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp; cjclark@alum.mit.edu<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span
></span
>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span
></span
>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp; cjclark@jhu.edu</blockquote>
<blockquote type="cite"
cite>http://people.freebsd.org/~cjc/&nbsp;&nbsp;&nbsp;
|&nbsp;&nbsp;&nbsp;&nbsp; cjc@freebsd.org</blockquote>
</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><tt>-- </tt></blockquote>
<blockquote type="cite" cite>&nbsp;</blockquote>
<blockquote type="cite" cite>David A. Koran<br>
(dak@solo.net) - http://www.solo.net/~dak/<br>;
<br>
PGP Key ID: 0x8AC39F65<br>
<br>
-----BEGIN GEEK CODE BLOCK-----<br>
Version: 3.1<br>
GIT/CS/SS d- s+: a- C+++$ UBLHSX++++$ P+++$ L- E--- W+++ N- o--
K-?<br>
w--- O- M+++$ V-- PS++ PE- Y+&gt;++ PGP t--@ 5 X+ R- tv b+ DI++++ D
G<br>
e*&gt;+++ h++ r y+<br>
------END GEEK CODE BLOCK------</blockquote>
<div><br></div>
<div><br></div>
<x-sigsep><pre>-- 
</pre></x-sigsep>
<div>David A. Koran<br>
(dak@solo.net) - http://www.solo.net/~dak/<br>;
<br>
PGP Key ID: 0x8AC39F65<br>
<br>
-----BEGIN GEEK CODE BLOCK-----<br>
Version: 3.1<br>
GIT/CS/SS d- s+: a- C+++$ UBLHSX++++$ P+++$ L- E--- W+++ N- o--
K-?<br>
w--- O- M+++$ V-- PS++ PE- Y+&gt;++ PGP t--@ 5 X+ R- tv b+ DI++++ D
G<br>
e*&gt;+++ h++ r y+<br>
------END GEEK CODE BLOCK------</div>
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