IP Masqerading

I have two boxes, One Linux, One Win2k

The Linux Box has two Ethernet Cards and the Windows box has one
Ethernet Card.

The Linux Box is connected to the internet and I want to use it so the
Win2k box can access the internet.

Is buying a Hub my only option?

What hardware options do I have?

Thanks
Peter

"Peter" <zpetero@netscape.net> wrote in message
news:5f09c2fb.0310191800.2a7a26be@posting.google.c om

> I have two boxes, One Linux, One Win2k
> The Linux Box has two Ethernet Cards and the Windows box has one
> Ethernet Card.
> The Linux Box is connected to the internet and I want to use it so the
> Win2k box can access the internet.
> Is buying a Hub my only option?
> What hardware options do I have?

No, a hub is not the only option.

You can buy a switch, which is preferable to a hub, or you can use a
crossover cable for a direct connection between the two machines.


tony

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On 19 Oct 2003 19:00:59 -0700, Peter wrote:
> I have two boxes, One Linux, One Win2k
>
> The Linux Box has two Ethernet Cards and the Windows box has one
> Ethernet Card.
>
> The Linux Box is connected to the internet and I want to use it so the
> Win2k box can access the internet.
>
> Is buying a Hub my only option?
>
> What hardware options do I have?

Hook linux to win2k with crossover cable and turn on linux box any
time you want to get to internet. Linux box can be inbound firewall.

In article <slrnbp6hd5.ut7.BitTwister@wb.home>, Bit Twister wrote:
> On 19 Oct 2003 19:00:59 -0700, Peter wrote:
>> I have two boxes, One Linux, One Win2k
>>
>> The Linux Box has two Ethernet Cards and the Windows box has one
>> Ethernet Card.
>>
>> The Linux Box is connected to the internet and I want to use it so the
>> Win2k box can access the internet.
>>
>> Is buying a Hub my only option?
>>
>> What hardware options do I have?
>
> Hook linux to win2k with crossover cable and turn on linux box any
> time you want to get to internet. Linux box can be inbound firewall.

I agree. A crossover cable is your best bet. You can either buy one
or make one. If you want to attach more than one device to your
firewall you will need a hub or a switch connected to your firewall.

Thanks guys! It would be nice if there was an adapter you could snap
onto a regular ethernet cable to make it a crossover cable but they're
cheap enough.

I knew about the switch but I'm not ready to shell out 200 bucks to go
wireless just yet. I just caught the Linux bug.

Peter

Bit Twister <BitTwister@localhost.localdomain> wrote in message news:<slrnbp6hd5.ut7.BitTwister@wb.home>...
> On 19 Oct 2003 19:00:59 -0700, Peter wrote:
> > I have two boxes, One Linux, One Win2k
> >
> > The Linux Box has two Ethernet Cards and the Windows box has one
> > Ethernet Card.
> >
> > The Linux Box is connected to the internet and I want to use it so the
> > Win2k box can access the internet.
> >
> > Is buying a Hub my only option?
> >
> > What hardware options do I have?
>
> Hook linux to win2k with crossover cable and turn on linux box any
> time you want to get to internet. Linux box can be inbound firewall.

Here's my setup,

PPP/ETH/etc. +------------+
+-------------+
to ISP provider | Linux #1 | PPP/ETH/etc. | Anybox
|
| | |
|
<DSL----eth0/ppp0--- |eth1-----------------eth0|
|
| | |
|
122.122.122.122 | | 10.0.0.2 |
|
+------------+
+-------------+

Next problem, I can browse the internet from Linux #1.
I can ping Linux #1 from Anybox(Win2k).

Anybox;
ip 10.0.0.2
Subnet 255.255.255.0
Default Gateway 122.122.122.122

ifconfig on Linux #1 returns
eth1
ip 10.0.0.1
Subnet 255.255.255.0

eth0 UP RUNNING BORADCAST MULTICAST

ppp0 ip 122.122.122.122
Subnet 255.255.255.255


I made the change outlined in this IP masquerading howto to change
eth0 to ppp0 and I'm not quite sure where to turn at this point.

http://en.tldp.org/HOWTO/IP-Masquera...-examples.html

Thanks,
Peter




zpetero@netscape.net (Peter) wrote in message news:<5f09c2fb.0310200730.1473c2b@posting.google.c om>...
> Thanks guys! It would be nice if there was an adapter you could snap
> onto a regular ethernet cable to make it a crossover cable but they're
> cheap enough.
>
> I knew about the switch but I'm not ready to shell out 200 bucks to go
> wireless just yet. I just caught the Linux bug.
>
> Peter
>
> Bit Twister <BitTwister@localhost.localdomain> wrote in message news:<slrnbp6hd5.ut7.BitTwister@wb.home>...
> > On 19 Oct 2003 19:00:59 -0700, Peter wrote:
> > > I have two boxes, One Linux, One Win2k
> > >
> > > The Linux Box has two Ethernet Cards and the Windows box has one
> > > Ethernet Card.
> > >
> > > The Linux Box is connected to the internet and I want to use it so the
> > > Win2k box can access the internet.
> > >
> > > Is buying a Hub my only option?
> > >
> > > What hardware options do I have?
> >
> > Hook linux to win2k with crossover cable and turn on linux box any
> > time you want to get to internet. Linux box can be inbound firewall.

On 20 Oct 2003 15:45:15 -0700, zpetero@netscape.net (Peter) wrote:
>Here's my setup,
>
>PPP/ETH/etc. +------------+
>+-------------+
>to ISP provider | Linux #1 | PPP/ETH/etc. | Anybox
> |
> | | |
> |
><DSL----eth0/ppp0--- |eth1-----------------eth0|
> |
> | | |
> |
> 122.122.122.122 | | 10.0.0.2 |
> |
> +------------+
>+-------------+
>
>Next problem, I can browse the internet from Linux #1.
>I can ping Linux #1 from Anybox(Win2k).
>
>Anybox;
>ip 10.0.0.2
>Subnet 255.255.255.0
>Default Gateway 122.122.122.122

Your default gateway should be the IP address of eth1, ie 10.0.0.1

>ifconfig on Linux #1 returns
>eth1
>ip 10.0.0.1
>Subnet 255.255.255.0
>
>eth0 UP RUNNING BORADCAST MULTICAST
>
>ppp0 ip 122.122.122.122
>Subnet 255.255.255.255
>
>
>I made the change outlined in this IP masquerading howto to change
>eth0 to ppp0 and I'm not quite sure where to turn at this point.
>
>http://en.tldp.org/HOWTO/IP-Masquera...-examples.html

Well, first off I'd recommend that you read the whole IP-Masq HOWTO if
you haven't done so already, it's an excellent guide to setting this
sort of stuff up and should teach you a lot.

Beyond that, are you sure that you've got your kernel configured with
all the correct options that are needed for IP masquerading? Are your
firewall/IP forwarding scripts causing any errors when you run them?

One other problem that you may encounter has to do with the MTU used.
The default MTU on ethernet is 1500, but with PPPoE you lose a few of
those bytes (usually 8). This can sometimes result in a problem where
your packets are getting fragmented and routers upstream routers are
not handling them properly. The symptoms of this are that your Linux
box would be able to browse the internet just fine, and your Windows
box would be able to ping internet sites and some connections would
work, but things like browsing and FTP would tend to fail. The
solution is to reduce the MTU on the Windows box to 1492 or sometimes
less. Of course, in typical Windows fashion, this sort of non-trvial
configuration is damn near impossible to do without downloading some
third-party tool (there is a registry key that you can add to change
your MTU, but it changes with every version of Windows and I can never
remember them).

"Peter" <zpetero@netscape.net> wrote in message
news:5f09c2fb.0310200730.1473c2b@posting.google.co m...
> Thanks guys! It would be nice if there was an adapter you could snap
> onto a regular ethernet cable to make it a crossover cable but they're
> cheap enough.
>
> I knew about the switch but I'm not ready to shell out 200 bucks to go
> wireless just yet. I just caught the Linux bug.

Actually, several vendors sell inline adapters which perform the crossover
magic. However, you can buy a 10 foot crossover cable for less. The
advantage is that you can stick the adapter into your tool bag and not have
to lug a bunch of cables with you all the time. If the inline adapter fixes
the problem, then you can get the crossover cable for a more permanent fix.

JW

I got it to work after the following,

Configuring rc.firewall file as follows;
1- Changing the /usr/local/sbin/iptable to where my iptable
2 - changing eth0 to ppp0

Then I added the DNS from my ISP to the client machine.

Peter

"Jacob Westenbach" <westy528@yahoo.com> wrote in message news:<Kzblb.2429$1U2.1908@twister.austin.rr.com>.. .
> "Peter" <zpetero@netscape.net> wrote in message
> news:5f09c2fb.0310200730.1473c2b@posting.google.co m...
> > Thanks guys! It would be nice if there was an adapter you could snap
> > onto a regular ethernet cable to make it a crossover cable but they're
> > cheap enough.
> >
> > I knew about the switch but I'm not ready to shell out 200 bucks to go
> > wireless just yet. I just caught the Linux bug.
>
> Actually, several vendors sell inline adapters which perform the crossover
> magic. However, you can buy a 10 foot crossover cable for less. The
> advantage is that you can stick the adapter into your tool bag and not have
> to lug a bunch of cables with you all the time. If the inline adapter fixes
> the problem, then you can get the crossover cable for a more permanent fix.
>
> JW

Peter <zpetero@netscape.net> wrote:
> I have two boxes, One Linux, One Win2k

> The Linux Box has two Ethernet Cards and the Windows box has one
> Ethernet Card.

> The Linux Box is connected to the internet and I want to use it so the
> Win2k box can access the internet.

> Is buying a Hub my only option?

> What hardware options do I have?

> Thanks
> Peter

I agree with Bit Twister as long as your requirement is
only one box connecting through the linux box then no
hub or switch is required.
Buy a typical crossover cable or block to go win to linux
then the other linux card to the internet.
The minute you add more machines it changes :)

This crossover just crosses the rx/tx connections so
the input of one is connected to the output of the other
and vice versa.

Hope this helps good luck!
-Walt


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