Why isn't it possible to access NATed services by the public IP address from LAN

sniffer · Nov 8, 2005, 7:18 PM

I all
I know i'm not the only one that ask for this question.
Did you think this options will be one day availlable on Pfsense?

I looking on the MonoWall WebSite, they told this option will never be availlable, its the same thing for PfSense?
" m0n0wall does not (and probably will not) include a "bounce" utility."

Jesse7 · Nov 8, 2005, 7:31 PM

Oh well least I am not the only one. Thanks for confirming this for me now I can stop wasting my time testing my own port forwarding LOL.

sullrich · Nov 8, 2005, 8:46 PM

Did you check the FAQ?

http://faq.pfsense.com/index.php?action=artikel&cat=8&id=29&artlang=en

sniffer · Nov 8, 2005, 9:01 PM

My English is so bad, sorry.I have some diffucltie to explain my self.

I read the FAQ long time ago.
I know i can reach my server trought the private IP, but i dont know if it work from the external range.
I have to put some proxy to see if it accessible from the outside.

It's why i want to know if some day, the Bouce option will be availlable on PacketFilter or its impossible du to the code?

Thanks

sullrich · Nov 8, 2005, 9:06 PM

@sniffer:

My English is so bad, sorry.I have some diffucltie to explain my self.

I read the FAQ long time ago.
I know i can reach my server trought the private IP, but i dont know if it work from the external range.
I have to put some proxy to see if it accessible from the outside.

It's why i want to know if some day, the Bouce option will be availlable on PacketFilter or its impossible du to the code?

Thanks

It's not impossible yet its not easy. Take a look at http://www.openbsd.org/faq/pf/rdr.html#reflect

I would happily commit patches if someone creates them, but as we are nearing 1.0 this is not on my priority list.

Jesse7 · Nov 8, 2005, 9:10 PM

Thanks Sullrich. I red the entire FAQ about 4 months ago when I was new to PF I guess I forgot about it.

Cyrandir · Nov 9, 2005, 12:37 AM

I think this should be included at some point. I know 1.0 is the priority right now and that's fine, but at some point this would be useful.

Jesse7 · Nov 9, 2005, 12:46 AM

I maybe a little confused but yeh it would be useful for testing if you don't have access to a seperation internet connection at least.

Sharaz · Nov 9, 2005, 2:36 AM

im not sure why you would access something that is already on your local lan, via its external ip address? (well i guess other than for testing).

Nov 9, 2005, 3:49 AM

Usually because there is one DNS name and that is for an outside address. yes, there are ways around this, but they are a hassle.

lsf · Nov 9, 2005, 9:08 AM

Well, this is how NAT works, you can't easily traverse it out and back in. So unless someone writes a patch to acomplish this i'd say no.
But to say never is a bit strong. Although I would not like my firewall doing this. For testing you should either get somone to test for you, or have a second link (dialup or whatever) to test with.
Another thing is that testing from the inside will never be the same as testing from the outside. Doing so will often give you more greif then you would like.
I know this from learning it the hard way, stuff working on the inside of our netwrok just not when crossing the border gateway, or testing stuff with DNS and using our own DNS in the process.

My wote to this kind of function would be no. It's just another "footshooting feature" in my opinion.

sniffer · Nov 9, 2005, 2:07 PM

@Sharaz:

im not sure why you would access something that is already on your local lan, via its external ip address? (well i guess other than for testing).

1-To test external DNS
2-To test some rules (The rule are not the same via the Lan NIC and the OPT1 NIC)

But with proxy, its possible to test it, but you have to search active proxy…

Thanks all for your answer

sullrich · Nov 9, 2005, 4:56 PM

@sniffer:

@Sharaz:

im not sure why you would access something that is already on your local lan, via its external ip address? (well i guess other than for testing).

1-To test external DNS
2-To test some rules (The rule are not the same via the Lan NIC and the OPT1 NIC)

But with proxy, its possible to test it, but you have to search active proxy…

Thanks all for your answer

Has anyone stopped to think of the ramifications of this feature? ALL traffic that would have been to the LAN would be sent THROUGH the firewall. What good is that when you could simply run split dns and keep all traffic LOCAL?

sniffer · Nov 9, 2005, 6:29 PM

yeah but modified /etc/hosts dont proved that external DynDns are ok.
And dont proved the Firewall Ruleset are ok to reach Web server in the DMZ via the WAN interface…

If i understand what you tell (Im very bad in English)

sullrich · Nov 9, 2005, 6:34 PM

@sniffer:

yeah but modified /etc/hosts dont proved that external DynDns are ok.
And dont proved the Firewall Ruleset are ok to reach Web server in the DMZ via the WAN interface…

If i understand what you tell (Im very bad in English)

Use the DNS forwarder to override hosts, not /etc/hosts. This is the same as m0n0wall. Check their docs out for more information.

sniffer · Nov 9, 2005, 6:51 PM

Ok, i will read on this DNS Forwarder…
Thank's for your support!

Sharaz · Nov 9, 2005, 10:03 PM

@sullrich:

Has anyone stopped to think of the ramifications of this feature? ALL traffic that would have been to the LAN would be sent THROUGH the firewall. What good is that when you could simply run split dns and keep all traffic LOCAL?

LMAO and what if you have one of those accounts where you pay by the megabit?? oops!

tmueko · Nov 10, 2005, 7:21 AM

It is possible, but not allways usefull:
Lets say 192.168.1.0/24 is LAN-Net with Host x.x.x.1(A) and x.x.x.2(B); 172.16.1.1(C) is Address of WAN; You have a NAT-Rule to pass Port-X to x.x.x.1; Normal Traffic from x.x.x.2 to 172.16.1.1 would be forwared without nat and the answer will be send from x.x.x.1 back to x.x.x.2: Bang. Make a NAT-Rule on the LAN Interface to rewrite all Traffic from x.x.x.2 to x.x.x.1 to come from 172.16.1.1.
Now Traffic comes from A to C, gets rewritten and Paket travel from C to B with source-address of C. The Answer from B will be send back to C and then after NAT Back to A with Source-Address of C…
clear :-))

tmueko

billm · Nov 11, 2005, 4:35 AM

@Sharaz:

@sullrich:

Has anyone stopped to think of the ramifications of this feature? ALL traffic that would have been to the LAN would be sent THROUGH the firewall. What good is that when you could simply run split dns and keep all traffic LOCAL?

LMAO and what if you have one of those accounts where you pay by the megabit?? oops!

Won't go out the WAN, just go through the firewall instead of staying on the local wire.

–Bill

sullrich · Nov 11, 2005, 5:21 PM

@billm:

@Sharaz:

@sullrich:

Has anyone stopped to think of the ramifications of this feature? ALL traffic that would have been to the LAN would be sent THROUGH the firewall. What good is that when you could simply run split dns and keep all traffic LOCAL?

LMAO and what if you have one of those accounts where you pay by the megabit?? oops!

Won't go out the WAN, just go through the firewall instead of staying on the local wire.

–Bill

Yup and simply burn up your firewalls throughput.