Port Forwarding

[Rishi Chopra]

James,

I've configured my Win2k box to contact DNS directly, and both Direct 
Connect and VNC Server are running smoothly (port forwarding is being 
accomplished (per your suggestion) by natd.conf).

I've set the firewall type to 'OPEN' (the Win2k client has ZoneAlarm 
protection of its own); this is truly the only sticking point.  I'm 
under the impression that selecting 'SIMPLE' rather than 'OPEN' provides 
an additional layer of protection to the gateway by preventing certain 
spoofing attacks.  Unfortunately, I seem unable to switch the firewall 
type without crippling my Win2k box's functionality.  Perhaps I'll give 
it a go again sometime in the future.


Here's a copy of the relevant files:

//natd.conf

unregistered_only
interface rl0
use_sockets
dynamic
redirect_port tcp 192.168.0.2:5800 5800
redirect_port tcp 192.168.0.2:5900 5900
redirect_port tcp 192.168.0.2:412 412
redirect_port tcp 192.168.0.2:1412 1412
punch_fw 2000:50

//rc.conf

gateway_enable="YES"
hostname="usha.dyndns.org"
ifconfig_rl0="DHCP"
ifconfig_rl1="inet 192.168.0.1 netmask 255.255.255.0"
kern_securelevel_enable="NO"
firewall_enable="YES"
firewall_type="OPEN"
# firewall_type="SIMPLE"
firewall_quiet="NO"
natd_enable="YES"
natd_interface="rl0"
natd_flags="-f /etc/natd.conf"
linux_enable="YES"
sendmail_enable="NO"
sshd_enable="YES"

-R

James Earl wrote:
> If you want your gateway to forward DNS queries from your private
> network, you will probably have to run named to answer the DNS queries
> and forward them out to your ISP's name servers.
> 
> You may also want to run a DHCP server.
> 
> I don't believe ipfw has the forwarding capability your looking for in
> this case.
> 
> You may want to get the DNS setup first, and then enable ipfw once you
> know that named is setup properly.
> 
> As for the firewall rules, you'd probably just have to modify slightly
> the DNS related ones that already exist under "SIMPLE."  Instead of
> letting DNS queries in from the outside, you want to let DNS queries in
> from the "inside."
> 
> Let me know if you have any other questions, and I'll try to help.
> 
> James
> 
> On Mon, 2004-01-19 at 21:06, Rishi Chopra wrote:
> 
>>If I want the gateway to forward DNS queries (e.g. have the win2k box 
>>query the gateway for DNS requests) what do I need to do?  What would 
>>the rule look like?
>>
>>James Earl wrote:
>>
>>
>>>On Mon, 2004-01-19 at 13:58, Rishi Chopra wrote:
>>>
>>>
>>>>What I want to do:  (1) Change firewall type from 'OPEN' to 'SIMPLE' and 
>>>>(2) Forward ports 412 and 5800 to my Win2k box.
>>>>
>>>>What I have:  The setup is pictured below. 
>>>>IPFIREWALL_DEFAULT_TO_ACCEPT, IPDIVERT and IPFILTER are all enabled in 
>>>>my kernel config file,  are also enabled.  Rule-of-thumb advice about 
>>>>"how best to secure a network" is not necessary in this case (the Win2k 
>>>>box has its own firewall installed (ZoneAlarm) and I already know too 
>>>>much about security).
>>>>
>>>>ISP          FreeBSD Gateway        Win2k Box
>>>>
>>>>
>>>>
>>>>>----------rl0--------------rl1-------------------<
>>>>
>>>>ALL        DHCP     192.168.0.1     192.168.0.2
>>>>
>>>>The problem:  When I chenge the firewall type to SIMPLE from OPEN, the 
>>>>Win2k box can no longer query DNS and pings to the 192.168.0.1 address 
>>>>do not work.  With the firewall type set to OPEN, there are no problems 
>>>>whatsoever.  I am also new to the IPFW syntax.
>>>>
>>>>What I would like to know is: (1) the syntax for forwarding incomming 
>>>>connections from rl0 to rl1 (and ultimately to 192.168.0.2) and (2) 
>>>>whether the syntax for allowing connections to the outside network (such 
>>>>as DNS) is correct and if some other problem is preventing the win2k box 
>>>
>>>>from querying DNS when SIMPLE is enabled.
>>>
>>>
>>>The FreeBSD Handbook can describe port redirection using NAT better than
>>>I can:
>>>
>>>http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/network-natd.html
>>>
>>>With the SIMPLE firewall rules, all your machines on your LAN should be
>>>able to establish connections.  Make sure that you have your ISP's DNS
>>>servers IP's specified on the win2k machine, and also that your FreeBSD
>>>machines IP is setup as the default gateway in win2k.
>>>
>>>You shouldn't be able to ping the FreeBSD gateway from the win2k machine
>>>because of the FreeBSD gateway's firewall.
>>>
>>>Anther test... try accessing a machine out on the Internet using it's ip
>>>address and see if you get out.
>>>
>>>James
>>>
>>>
>>>
> 
> 
>