About My Network

My Current Network

I have DSL service and have 5 static IP addresses (206.124.146.176-180). My DSL "modem" (Fujitsu Speedport) is connected to eth0. I have a local network connected to eth2 (subnet 192.168.1.0/24) and a DMZ connected to eth1 (192.168.2.0/24).

I use:

Static NAT for ursa (my XP System) - Internal address 192.168.1.5 and external address 206.124.146.178.

Proxy ARP for wookie (my Linux System). This system has two IP addresses: 192.168.1.3/24 and 206.124.146.179/24.

SNAT through the primary gateway address (206.124.146.176) for my Wife's system (tarry) and the Wireless Access Point (wap)

The firewall runs on a 128MB PII/233 with RH7.2 and Kernel 2.4.19.

Wookie runs Samba and acts as the a WINS server. Wookie is in its own 'whitelist' zone called 'me'.

My laptop (eastept1) is connected to eth3 using a cross-over cable. It runs its own Sygate firewall software and is managed by Proxy ARP. It connects to the local network through the PopTop server running on my firewall.

The single system in the DMZ (address 206.124.146.177) runs postfix, Courier IMAP (imaps and pop3), DNS, a Web server (Apache) and an FTP server (Pure-ftpd). The system also runs fetchmail to fetch our email from our old and current ISPs. That server is managed through Proxy ARP.

The firewall system itself runs a DHCP server that serves the local network.

All administration and publishing is done using ssh/scp.

I run an SNMP server on my firewall to serve MRTG running in the DMZ.

The ethernet interface in the Server is configured with IP address 206.124.146.177, netmask 255.255.255.0. The server's default gateway is 206.124.146.254 (Router at my ISP. This is the same default gateway used by the firewall itself). On the firewall, Shorewall automatically adds a host route to 206.124.146.177 through eth1 (192.168.2.1) because of the entry in /etc/shorewall/proxyarp (see below).

A similar setup is used on eth3 (192.168.3.1) which interfaces to my laptop (206.124.146.180).

Note: My files use features not available before Shorewall version 1.3.4.

Shorewall.conf

	SUBSYSLOCK=/var/lock/subsys/shorewall
	STATEDIR=/var/state/shorewall

	LOGRATE=
	LOGBURST=

	ADD_IP_ALIASES="Yes"

	CLAMPMSS=Yes

	MULTIPORT=Yes

Zones File:

	#ZONE 	DISPLAY 	COMMENTS
	net	Internet	Internet
	me	Eastep		My Workstation
	loc	Local		Local networks
	dmz	DMZ		Demilitarized zone
	tx	Texas		Peer Network in Dallas Texas
	#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE

Interfaces File:

This is set up so that I can start the firewall before bringing up my Ethernet interfaces.

	#ZONE    INTERFACE	BROADCAST 	OPTIONS
	net	eth0 		206.124.146.255	routefilter,norfc1918,blacklist,filterping
	loc	eth2 		192.168.1.255	dhcp
	dmz	eth1 		206.124.146.255	-
	net	eth3		206.124.146.255 norfc1918
	-	texas 		-
	loc	ppp+
	#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

Hosts File:

	#ZONE 		HOST(S)			OPTIONS
	me		eth2:192.168.1.3,eth2:206.124.146.179
	tx 		texas:192.168.9.0/24
	#LAST LINE -- ADD YOUR ENTRIES ABOVE -- DO NOT REMOVE

Routestopped File:

	#INTERFACE	HOST(S)
	eth1		206.124.146.177
	eth2 		-
	eth3 		206.124.146.180

Common File:

	. /etc/shorewall/common.def
	run_iptables -A common -p udp --sport 53 -mstate --state NEW -j DROP
	run_iptables -A common -p tcp --dport 113 -j REJECT

Policy File:


	#SOURCE	DEST	POLICY	LOG LEVEL	LIMIT:BURST
	me	all	ACCEPT
	tx	me	ACCEPT		#Give Texas access to my personal system
	all	me	CONTINUE	#WARNING: You must be running Shorewall 1.3.1 or later for
					#	  this policy to work as expected!!!	
	loc 	loc 	ACCEPT
	loc 	net	ACCEPT
	$FW	loc	ACCEPT
	$FW	tx	ACCEPT
	loc	tx	ACCEPT
	loc	fw	REJECT
	net	net	ACCEPT
	net	all	DROP	info		10/sec:40
	all	all	REJECT	info
	#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOTE

Masq File:

Although most of our internal systems use static NAT, my wife's system (192.168.1.4) uses IP Masquerading (actually SNAT) as do visitors with laptops.

	#INTERFACE 	SUBNET		ADDRESS
	eth0 		192.168.1.0/24	206.124.146.176
	#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE

NAT File:

	#EXTERNAL	INTERFACE	INTERNAL	ALL	LOCAL
	206.124.146.178 eth0 		192.168.1.5 	No 	No
	206.124.146.179 eth0 		192.168.1.3 	No 	No
	#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE

Proxy ARP File:

     	#ADDRESS	INTERFACE	EXTERNAL	HAVEROUTE
	206.124.146.177 eth1 		eth0 		No
	206.124.146.180	eth3		eth0		No
	#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

Rules File (The shell variables are set in /etc/shorewall/params):

     	#ACTION		SOURCE 		DEST 			PROTO	DEST 	SOURCE  ORIGINAL
	#                       				PORT(S) PORT(S)	PORT(S)	DEST
	#
	# Local Network to Internet - Reject attempts by Trojans to call home
	#
	REJECT:info 	loc 		net 			tcp	6667
	#
	# Local Network to Firewall 
	#
	ACCEPT		loc		fw 			tcp 	ssh
	ACCEPT		loc		fw			tcp	time
	#
	# Local Network to DMZ 
	#
	ACCEPT 		loc 		dmz 			udp	domain
	ACCEPT		loc		dmz			tcp	smtp
	ACCEPT		loc		dmz			tcp	domain
	ACCEPT		loc		dmz			tcp	ssh
	ACCEPT		loc		dmz			tcp	auth
	ACCEPT		loc		dmz			tcp	imap
	ACCEPT		loc		dmz			tcp	https
	ACCEPT		loc		dmz			tcp	imaps
	ACCEPT		loc		dmz			tcp	cvspserver
	ACCEPT 		loc 		dmz 			tcp 	www
	ACCEPT		loc		dmz			tcp	ftp
	ACCEPT		loc		dmz			tcp	pop3
	ACCEPT		loc		dmz			icmp	echo-request
	#
	# Internet to DMZ 
	#
	ACCEPT		net		dmz 			tcp	www
	ACCEPT		net		dmz			tcp	smtp
	ACCEPT		net		dmz			tcp	ftp
	ACCEPT		net		dmz			tcp	auth
	ACCEPT		net		dmz			tcp	https
	ACCEPT		net		dmz			tcp	imaps
	ACCEPT		net		dmz			tcp	domain
	ACCEPT		net		dmz			tcp	cvspserver
	ACCEPT		net		dmz			udp	domain
	ACCEPT		net		dmz			icmp	echo-request
	ACCEPT 		net:$MIRRORS	dmz			tcp	rsync
	#
	# Net to Me (ICQ chat and file transfers) 
	#
	ACCEPT		net		me			tcp	4000:4100
	#
	# Net to Local 
	#
	ACCEPT		net		loc			tcp	auth
	REJECT		net		loc			tcp	www
	#
	# DMZ to Internet
	#
	ACCEPT		dmz		net			icmp	echo-request
	ACCEPT		dmz		net			tcp	smtp
	ACCEPT		dmz		net			tcp	auth
	ACCEPT		dmz		net			tcp	domain
	ACCEPT		dmz		net			tcp	www
	ACCEPT		dmz		net			tcp	https
	ACCEPT		dmz		net			tcp	whois
	ACCEPT		dmz		net			tcp	echo
	ACCEPT		dmz		net			udp	domain
	ACCEPT		dmz 		net:$NTPSERVERS		udp	ntp
	ACCEPT 		dmz 		net:$POPSERVERS		tcp	pop3
	#
	# The following compensates for a bug, either in some FTP clients or in the
	# Netfilter connection tracking code that occasionally denies active mode
	# FTP clients
	#
	ACCEPT:info 	dmz 		net			tcp	1024:	20
	#
	# DMZ to Firewall -- snmp
	#
	ACCEPT 		dmz 		fw 			tcp	snmp
	ACCEPT		dmz		fw			udp	snmp
	#
	# DMZ to Local Network 
	#
	ACCEPT 		dmz 		loc			tcp	smtp
	ACCEPT		dmz		loc			tcp	auth
	ACCEPT		dmz		loc			icmp	echo-request
	# Internet to Firewall
	#
	ACCEPT		net		fw			tcp	1723
	ACCEPT		net		fw			gre
	REJECT 		net		fw			tcp	www
	#
	# Firewall to Internet
	#
	ACCEPT 		fw 		net:$NTPSERVERS		udp	ntp
	ACCEPT		fw		net			udp	domain
	ACCEPT		fw		net			tcp	domain
	ACCEPT		fw		net			tcp	www
	ACCEPT		fw		net			tcp	https
	ACCEPT		fw		net			tcp	ssh
	ACCEPT		fw		net			tcp	whois
	ACCEPT		fw		net 			icmp	echo-request
	#
	# Firewall to DMZ
	#
	ACCEPT 		fw 		dmz 			tcp 	www
	ACCEPT 		fw 		dmz 			tcp 	ftp
	ACCEPT 		fw 		dmz 			tcp 	ssh
	ACCEPT 		fw 		dmz 			tcp 	smtp
	ACCEPT 		fw 		dmz 			udp 	domain
	#
	# Let Texas Ping
	#
	ACCEPT 		tx 		fw 			icmp 	echo-request
	ACCEPT		tx 		loc 			icmp 	echo-request

	#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

Last updated 9/14/2002 - Tom Eastep