[MLB-WIRELESS] linux q

Jason Hecker jhecker at wireless.org.au
Thu Apr 22 09:55:23 EST 2004

> is there a limit to the amount of ip's one nic can have?

Dunno what the limit is, but a NIC can have more than one IP.

> i want a box with 2 wireless cards and 1 eth port to be able to do
> melbwireless/wan/lan thru the eth port is that possible?
> or do i need atleast 2 eth ports?

No.  One is fine.  Though do you mean the wireless cards and the eth 
card are in the same computer?

> how do you set a eth port to have more than 1 ip?

For example, if eth0 is already set up as and you want to 
set it up to do as well, as root in the shell just type

ifconfig eth0 add

This will create eth0:0 with the new address range which the card will 
now listen to as well.  For packets to get from 192.168.1.x to 
192.168.2.x this machine will act as the router as well as the machines 
on 192.168.1.x and 192.168.2.x having their gateways to the other nets 
as and respectively.

> could 1 box run nocat for a free net answer to my area as well as
> melbwireless on a diff ip range and my home network on full net and then
> with the optus cable plugging str8 in?
> or do i need 2/3/4 boxes?

The problem with running separate networks like this off the one 
ethernet card is your security is laxer.  The wireless devices will 
simply broadcast out any broadcasts that exist on the port, no matter 
what the subnet is - this includes stuff like windows file networking 
information and whatever else uses broadcasts.  To be properly secure, 
the optus modem should have it's own eth card, the wireless network 
should have it's own eth card and your internal net should have it's own 
eth card.  That way you have absolute control over what traffic goes 
where.  Wireless devices set in AP mode don't care what the IP addresses 
are, they just send the ethernet frames on regardless of the content. 
The reason an AP has an IP address is so you can connect to the 
controller on it with a web browser, for instance.

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