routing confusion on home network

Kevin O'Connor kevin at ziptek-technologies.co.uk
Tue Mar 15 20:39:54 GMT 2005


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Nicely put Lee that is indeed the reason. Can I please have several glasses
of whatever type of beer you're drinking :-)
 
Kel
The Netgear will have a default route to the public IP connection, it cannot
build a routing table to different subnets( you can only get away with stuff
like that on layer3 or better switches which learn routes via RIP or OSPF)
Unless it's a typo the Gentoo Linux PC (eth0: 192.168.5.2, default route:
192.168.5.1) should read
Gentoo Linux PC (eth0: 192.168.5.2, default route: 192.168.5.3) 
As the 192.168.5.3 interface on the FreeBSD box is the gateway not the ADSL
4-port modem/router. 
You also wonder about the Network/sub-net setup. These terms date back to
the early days of TCP/IP when splitting a class A, B or C network up into
smaller sub-nets was impossible. hence terms like Class A network. However
with the introduction of more advanced network masking (CIDR) it became
possible to split up these standard networks into smaller (Sub Net)
segments. As a point of interest it also became possible to join several
Class C networks into a single Class B network (Super net) So the term
Network, subnet and supernet are, from a routing point of view, the same
thing.
 
I'd be curious to know why you have this particular setup.
 
Regards
Kevin 
 
>-----Original Message-----
>From: freebsd-users-admin at uk.freebsd.org [mailto:freebsd-users-
>admin at uk.freebsd.org] On Behalf Of Lee Brotherston
>Sent: 15 March 2005 14:37
>To: kel at orawia.com
>Cc: freebsd-users at uk.freebsd.org
>Subject: Re: routing confusion on home network
> 
>Kel Graham wrote:
>> ah.. solved it by judicious use of NAT.  Why does FreeBSD say it routes
>> between interfaces with a simple "gateway_enable='YES'", when for me this
>> wasn't the case? Was it because I have two separate networks, and not
>just
>> different subnets?
> 
>Hi Kel,
> 
>I suspect that the FreeBSD box was infact routing the traffic fine,
>however the netgear router had no routes for 192.168.5.0/24 to enable
>the return traffic back (a tcpdump should confirm this).  It would need
>a gateway of 192.168.0.26 setting for any 192.168.5.0/24 traffic in the
>router.  Using NAT means that the traffic used the address of the
>interface on the FreeBSD machine which the router could route too by
>virtue of being on the same subnet.
> 
>Wow, did I just type that after beer? :)
> 
>   Lee
> 
>------ FreeBSD UK Users' Group  -  Mailing List ------
>http://listserver.uk.freebsd.org/mailman/listinfo/freebsd-users

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<div class=3DSection1>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span style=3D=
'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span style=3D'fon=
t-size:10.0pt;
font-family:"Courier New"'>Nicely put Lee that is indeed the reason. Can I
please have several glasses of whatever type of beer you're drinking :<span
class=3DGramE>-)</span><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span style=3D'fon=
t-size:10.0pt;
font-family:"Courier New"'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><font size=3D2 face=3D"Courier Ne=
w"><span
style=3D'font-size:10.0pt;font-family:"Courier New"'>Kel</span></font></spa=
n><font
size=3D2 face=3D"Courier New"><span style=3D'font-size:10.0pt;font-family:"=
Courier New"'><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span style=3D'fon=
t-size:10.0pt;
font-family:"Courier New"'>The <span class=3DSpellE>Netgear</span> will hav=
e a
default route to the public IP connection, it cannot build a routing table =
to
different <span class=3DGramE>subnets(</span> you can only get away with st=
uff
like that on layer3 or better switches which learn routes via RIP or OSPF)<=
o:p></o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>Unless it's a typo the <span class=3DSpellE>Gentoo</span> Linux PC =
(eth0:
192.168.5.2, default route: 192.168.5.1) should read<o:p></o:p></span></fon=
t></p>

<p class=3DMsoPlainText><span class=3DSpellE><font size=3D2 face=3D"Courier=
 New"><span
style=3D'font-size:10.0pt'>Gentoo</span></font></span> Linux PC (eth0:
192.168.5.2, default route: 192.168.5.3) <o:p></o:p></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>As the 192.168.5.3 interface on the FreeBSD box is the gateway not =
the ADSL
4-port modem/router. <o:p></o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>You also wonder about the Network/sub-net setup. These terms date b=
ack
to the early days of TCP/IP when splitting a class A, B or C network up into
smaller sub-nets was impossible. <span class=3DGramE>hence</span> terms like
Class A network. However with the introduction of more advanced network mas=
king
(CIDR) it became possible to split up these standard networks into smaller =
(Sub
Net) segments. As a point of interest it also became possible to join sever=
al
Class C networks into a single Class B network (Super net) <span class=3DGr=
amE>So</span>
the term Network, subnet and <span class=3DSpellE>supernet</span> are, from=
 a
routing point of view, the same thing.<o:p></o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>I'd be curious to know why you have this particular setup.<o:p></o:=
p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>Regards<o:p></o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>Kevin <o:p></o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;-----Original Message-----</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;From: freebsd-users-admin at uk.freebsd.org [mailto:freebsd-users-=
</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;admin at uk.freebsd.org] On Behalf Of Lee Brotherston</span></font=
></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Sent: 15 March 2005 14:37</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;To: kel at orawia.com</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Cc: freebsd-users at uk.freebsd.org</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Subject: Re: routing confusion on home network</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Kel Graham wrote:</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;&gt; ah.. solved it by judicious use of NAT.<span
style=3D'mso-spacerun:yes'>&nbsp; </span>Why does FreeBSD say it routes</sp=
an></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;&gt; between interfaces with a simple
&quot;gateway_enable=3D'YES'&quot;, when for me this</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;&gt; wasn't the case? Was it because I have two separate networ=
ks,
and not</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;just</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;&gt; different subnets?</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Hi Kel,</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;I suspect that the FreeBSD box was infact routing the traffic f=
ine,</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;however the netgear router had no routes for 192.168.5.0/24 to
enable</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;the return traffic back (a tcpdump should confirm this).<span
style=3D'mso-spacerun:yes'>&nbsp; </span>It would need</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;a gateway of 192.168.0.26 setting for any 192.168.5.0/24 traffi=
c in
the</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;router.<span style=3D'mso-spacerun:yes'>&nbsp; </span>Using NAT=
 means
that the traffic used the address of the</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;interface on the FreeBSD machine which the router could route t=
oo
by</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;virtue of being on the same subnet.</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;Wow, did I just type that after beer? :)</span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<span style=3D'mso-spacerun:yes'>&nbsp;&nbsp; </span>Lee</span>=
</font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;<o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;------ FreeBSD <st1:country-region w:st=3D"on"><st1:place w:st=
=3D"on">UK</st1:place></st1:country-region>
Users' Group<span style=3D'mso-spacerun:yes'>&nbsp; </span>-<span
style=3D'mso-spacerun:yes'>&nbsp; </span>Mailing List ------</span></font><=
/p>

<p class=3DMsoPlainText><font size=3D2 face=3D"Courier New"><span style=3D'=
font-size:
10.0pt'>&gt;http://listserver.uk.freebsd.org/mailman/listinfo/freebsd-users=
</span></font></p>

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