Re: NEWBIE: RH Linux and ProCurve VLAN Setup

Hi again Eric,

On Mon, Jan 09, 2006 at 04:10:41PM -0500, Eric Maynard wrote:
> Thanks Peter.
> 
> Your reply has left me with a real warm-fuzzy feeling about all
> this and a desire to make this work more than ever.

Great! :)


> I know I've some more researching ahead of me as I will need to solve
> the issue of NATing from my firewall

NAT is a oneliner:

iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o eth0 -j MASQUERADE

or possibly:

iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o eth0 -j SNAT --to 1.2.3.4

MASQUERADE automatically SNAT:s to the first IP address on the
outgoing interface. SNAT requires you to specify a static IP in the
rule.

Both these rules assume that your internal network is 192.168.42.0/24
and that the external interface (connected to ISP router) is eth0.

Learn iptables from:

http://iptables-tutorial.frozentux.net/iptables-tutorial.html
http://www.netfilter.org/documentation/HOWTO//NAT-HOWTO.html

and other links at:

http://www.netfilter.org/documentation/

Make sure you enable IP forwarding as noted before, otherwise Linux
just doesn't route anything.


> as well as how to teach it how to prioritize, but if I can at least
> get it route the packets inter-VLAN for now, I will consider this a
> successful purchase and start to the implementation.

Inter-VLAN-traffic isn't routed but bridged. Routing only happens
when traffic is forwarded from one IP network to another, so
internal <-> internet traffic will be routed.


> thanks again and I will be in touch,

I hope you'll get it all to work!

Oh, another thing I mention in a follow-up to the original thread
with the nice ASCII:

vconfig set_flag vlan2 1 1

is required for each virtual VLAN interface in Linux in order to get
dhcpd to run properly.


//Peter