on a more fundamental note ... the purpose of a router/firewall is to
seperate network segments and control what stuff can move between them ...
as a very basic example with three network cards consider this very
traditional layout ...
 
Network 1 = LAN, all internal workstations
Network 2 = DMZ (demilitarized zone), servers that must have limited
exposure to the Internet
Network 3 = WAN, the Internet at large ...
 
you would setup such a system so that all three are unique IP address
blocks, maybe something like this ...
 
Network 1 = 192.168.0.0/255.255.255.0, 254 private non-routable IP addresses
Network 2 = 192.168.1.0/255.255.255.0, 254 private non-routable IP addresses
Network 3 = 68.168.1.31/255.255.255.248, 16 public routable IP addresses
provided by your ISP
 
your equipment would then be connected as follows ...
 
Network 1, internal workstations, phones, printers and such that should be
protected from internet attack
Network 2, email server, web server, Asterisk server and others that for
whatever reason must be exposed to the internet to do the assigned task
Network 3, danger zone where none of your precious equipment should reside
 
once this is topology is in place, you would then control which "ports"
(think of them like channels on the TV) will be allowed to pass between the
segments ... this is what the firewall does ... lets you open small holes in
the wall that only allows that traffic which must pass between network
segments ...
 
it is possible to have 4, 5 or however many network segments you need
depending on the complexity of your requirement ... maybe you dont need a
DMZ but do need to support wireless ... so you would setup your Network 2 to
be a wireless "Int2" network instead of being a DMZ ... but for routing
between Int2 and the other segments to work properly, it must be on a unique
network segment (IP address range) ...  and you would need to devise a set
of rules that determine what data can pass between "Int1", Int2" and "Wan"
 
these days it is not uncommon to setup two WAN interfaces to provide load
balancing between two Internet connections ... so the variety of possible
configurations is large ...
 
This is VERY basic info ... this topic could easily fill a book or two ... I
hope this helps those who are unfamiliar with routing and firewall in
general get an idea of the basics from a 50,000 foot view ...  when it gets
down to the details, Google is your friend ...  documentation for the
m0n0wall and/or pFsense projects will provide a lot of ideas on specific
situations ...
 
G.Hendershot

  _____  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Mark van Berkel
Sent: Sunday, December 03, 2006 9:51 AM
To: [EMAIL PROTECTED]
Subject: [Astlinux-users] Configuring Astlinux to act as a router


I apologize if this got sent twice.  I have been having problems with my
e-mail...mostly my fault.

I need some guidance and help on configuring my Astlinux box to act as a
router/firewall as well as a great PBX!  I am not a networking expert so
likely some of my problems are likely not having a complete understanding of
IP networks.

Here is my setup:

I have 2 wired ethernet interfaces (one is a ASIX USB dongle), and an
Atheros wi-fi card setup as a AP.  All hardware is up and working. Calls to
my IAX provider over the internet work fine.

(snipped from my rc.conf)

EXTIF=eth0   (this is connected to an upstream DHCP router providing
Internet access.  The IP address assigned is in the range of 192.168.1.1xx)

INTIF=ap0
INTIP=192.168.2.1
INTNM=255.255.255.0

INT2IF=eth1
INT2IP=192.168.2.2
INT2NM=255.255.255.0

DMZ=extme

DENYACT="DROP"

I want to provide DHCP services on to the clients on INTIF and INT2IF (ap0 &
eth1), access to the Asterisk server and Internet connectivity.  The DHCP
server is working and assigning IP addresses.

I have tried bridging the various interfaces (eth1 and ap0, eth0 and ap0,
etc) buy no joy.  If anyone could point me to some documentation/wiki/FAQ on
this it would be appreciated.

Mark 
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