Linux Proxy NIC interfacing woes

[Wass]

Derek Martin hath scribed:
>On Fri, 24 Dec 1999, Wass wrote:
>> 	I've got a cable-modem, which I've successfully used with linux
>> for several months now, with a Acer card (compatible with Via-Rhine).
>> After getting a new computer, some NIC's, and an 8-port hub, I decided
>> to try my hand at setting up a LAN.  
>
>I'm not sure exactly what you mean by "proxy" because it can have a couple
>of different (but similar) meanings, but I think you mean you want one
>machine to act as a gateway for your network.  If not, the next couple of
>paragraphs will be of limited use to you, but should still be at least
>somewhat helpful.

Hi Derek,

	Yes, you are correct.  I would like my Pentium box to connect
to my cable modem, and also connect to my LAN.  When referring to this
box, I'm calling it a proxy, for simplicity.

>If the Acer card is the one that you originally set up your cable modem
>for, then that's the only one that will get an IP address from the cable
>modem.  The cable company takes the MAC address of the card you set it up
>with and only provides DHCP to THAT CARD.  Therefore if you want to make a
>different machine a proxy server, you need to put the Acer card in it, and
>connect it to the cable modem. Or call the cable company and tell them you
>got a new ethernet card, and give them the MAC address for that card.  
>Then you need to put a second NIC in it, and assign it a static IP address
>on a private address block, such as 192.168.1.1 and stick it in your hub.

Do you know if this is true for all cable companies?  My provider is RCN,
and I remember reading somethinb awhile back about cycling power to the
cable box, to reset the networkgfor the new MAC address.
>
>Now configure your second machcard with another static IPI'm not sure,
but I think that a few weeks back, when attempting to configure OpenBSD,
I got my cable-modem connected to this box with the dual 3c905's (it
took a few tries to figure out with of the two NIC's was eth0 and eth1).
I'm not too positive, but I think I was convinced that cable-modem
connection wasn't a problem back then, so I didn't think about it too much. 
that same network, and stick it in the hub.  Configure the default route
>on the second machine to point to the first machine, and set up IP
>masquerading using ipchains.  See the ipchains howto.
>
Yes, this is what I plan to do, but I'd like to set up the NIC for the
cable modem first.  
>> 

>> 	I've gone through the dhcpcd mini-HOWTO to get things started.
>> This thing is very out of date!  Are there any plans to add entries for
>> Mandrake 6.x to it?  I'd help out with his task, if I can get my box running
>.
>I doubt it -- these documents tend to be as distribution independent as
>possible.  But if you feel some info is out of date, I suggest you contact
>the author/maintainer who should be mentioned in that document somewhere.
>
>But also, I don't think DHCP is your problem.  I'm still not quite sure
>what effect you're trying to achieve, since you never specifically
>mentioned how you want to use this "proxy" server.  But it sounds to me
>like you don't quite have a handle on what your design needs to look like.

No, you were correct above.  I plan to have a bunch of connected computers
throughout my house, and hope to give them internet access.  So,I
plan to have the box I've called the 'proxy' configured with two NIC's,
one connected to the cable modem, and the other connected to my 8-port
hub.  Then, of course, I'll connect the other computers to the hub.  Is
this mostly right?  I'm new to this networking thing.

>Again, the only card that will get an IP address via DHCP is the one that
>is directly connected to your CM, whose MAC address was supplied to your
>cable company (either by you or by the technician that did the install).
>Any other ethernet card anywhere else in your network will need to be
>configured statically, unless you set up your own DHCP server to serve IP
>addresses to them.  But where you have so few machines, this is hardly
>worth the effort to set up, unless you just want to learn how to do it.
>
>If you do set one up, you want to make sure you're not serving DHCP out to
>the network your CM is on... your cable company will probably not like
>that too much. Your best bet is to make sure you DON'T install the server
>on the machine that's connected to the CM.

Yes, I'm planning on only getting a DHCP address for the cable-modem NIC,
and use static IP's (the ones guaranteed not to be denoted to valid
IP's) for the other computers.

>> 	It alludes to this possibility in the dhcpcd mini-howto, but
>> says that if the card is set to 100baseT, just change that setting.  there
>> is no detail/info about how to go about this.
>
>You probably will not need to worry about that.  Unless you have an older
>card, or a really crappy one, the card connected to the CM should
>auto-sense to 10Mb. I don't have any experience with those Acer cards, so
>I can't say how well the auto-negotiate.

No, it should be fairly modern, it's a 3com 3c905 Boomerang (or so says
my dmesg bootup messages).  

>> 	I've also played around with various module commands.  Trying
>> "insmod 3c90x" I get an error: "3c90x.o: init_module: Device or resource bus
>y"
>> Why could this be?  ANd I've seen vague implications that I may also
>> need to include the 3c59x module, is this true too?
>
>It probably means that either you have support for that card compiled into
>your kernel already, or possibly that you don't have such a card.  As for
>loading the extra module, you only need one of them... whichever is the
>right one for your card.

Well, I recompiled the kernel first, and set 3c905 support to be compiled
into the kernel, but I wanted to see how modprobe would react, so I 
recompiled the kernel with 3c905 for the module option.  Is there a way
to check to ensure that the 3c905 was not automatically included into the ker
the check that the 3c905 module isn't compiled into the kernel, and is
in fact set for dynamic module insertion?

>> 	Also, ifconfig shows only the 'lo' interface, not eth0.
>
>If the card hasn't been configured (via DHCP or an ifconfig command), it
>will only show up if you do
>  
>  ifconfig -a
>
>Also, if you don't have the right module loaded, it won't show up at all,
>even with the -a option.  Another way to know if the driver is loaded is
>to check for messages about your card(s) in the output of the dmesg
>command right after boot time, or to watch closely for such messages as
>the system boots.

Okay, I'll check that tomorrow.  (I'm at my folks house in NJ tonite).
Also, I can post the exact message dmesg gives about the card, I only
included a small part of it in the previous post.  I do know that it
acknowledges both eth0 and eth1 cards (ie, both 3c905's), and it cycles
through the exact same configuration messages for each card 3 times.  That
seemed kind of weird.

>Note that I've heard SOME cable companies will let you put the CM on a
>hub, and configure several machines via DHCP, but you'll still need to
>supply them with the MAC address of ALL the ethernet cards, and this
>option usually costs extra $$.  I think a friend told me MediaOne does
>this now.  Maybe Niall K. can comment on that.  Niall?

No, I just want the one card with DHCP, and setup the proxy to handle
the other computers.
I'll let you know what I can find out when I'm back at my Somerville
home tomorrow.
Thanks for responding, and happy holidays!

	- wass
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