[Gllug] Virtual IP addresses on a Linux box

[Bruce Richardson]

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 7/9/01, 1:03:14 PM, Xander D Harkness <xander at harkness.co.uk> wrote 
regarding Re: [Gllug] Virtual IP addresses on a Linux box:


> Oooh How exciting!  New config methods. :-)

> I am still using the ?old? eth:0... way

> I have not heard of the ip addr add ... dev eth0 method, do you have 
the
> commands, man page, web url ?

It's part of the iproute suite.  Should be a package available for 
your distro of choice.  If you configure your kernel as an advanced 
router then the ip tool lets you do policy routing with ease.

We have a leased line and an ADSL line and I recently put in a box to 
act as default gateway on our network.  It has 3 ethernet interfaces, 
one to the network and one to each line.  The iproute tools made it a 
doddle to route our user workstations through the fast but unreliable 
ADSL and our servers (smtp, pop) through the leased line by doing 
source-address based policy routing.

You can set up rules to route by source address, destination address, 
interface, TOS or fwmark.  If you use ipchains (to add a particular 
TOS or fwmark) in conjunction with ip you can set up any kind of 
policy routing you like - routing by port etc.

ip also does NAT, which means you can separate your NAT from your 
firewall rules.

And it all works with 2.2.

To keep my Debian boxes easily maintainable/upgradeable I still let 
ifconfig set up the basic interfaces but have if-up scripts which use 
ip to do the clever stuff.

-- 

Bruce




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