NAT issues with multi-WAN

sai

it's the return path where the packets are being sent to the gateway when they shouldn't be.

generally means the netmask is wrong but I am not sure how VIPs (and associated netmask) work in this…

now this is weird:

11:54:47.266968 00:50:8b:cf:a2:6a > 00:30:94:01:e7:90, length 62: (tos 0x0, ttl 63, id 38111, flags [DF], proto: TCP (6), length: 48) 12.34.56.24.22 > 12.34.56.241.3490: S, cksum 0xbcfc (correct), 3571569917:3571569917(0) ack 2188962038 win 5840 <mss 1460,nop,nop,sackok="">11:54:49.492704 00:50:8b:cf:a2:6a > 00:20:ed:91:f7:04, length 62: (tos 0x0, ttl 63, id 1468, flags [DF], proto: TCP (6), length: 48) 12.34.56.24.22 > 12.34.56.241.3479: S, cksum 0x6e76 (correct), 2180526778:2180526778(0) ack 2586252549 win 5840 <mss 1460,nop,nop,sackok="">2 consecutive packets, both from 12.34.56.24 both to 12.34.56.241 but (looking at the MAC address ) one goes to the gateway (ie the T1 modem) the other goes to the correct server.

all I can say is "wtf?". this problem really needs a guru</mss></mss>

Briantist

:sigh: I always get the crazy problems no one has ever heard of.

Keep in mind this doesn't really relate to the VIP/ProxyARP/1:1 NAT, since the problem happens on the interface address.

I have looked at the routing table, and it seems fine to me. I don't pretend to understand all of the fields, but it looks okay to me:

12.34.56 link#3 UC 0 0 1500 fxp2
12.34.56.1 00:30:94:01:e7:90 UHLW 1 24400 1500 fxp2 1179
12.34.56.3 00:20:ed:66:79:34 UHLW 1 124 1500 fxp2 1148
12.34.56.241 00:20:ed:91:f7:04 UHLW 1 26009 1500 fxp2 1192

(this is just the part of the routing table with 12.34.56 addresses)

GruensFroeschli

I'll set a test-network up today evening and try to recreate your problem.
This seems to be a really strange problem.

Briantist

Thanks a lot; I really appreciate it. If you have any additional questions, you contact me directly at brian-NATissue@briantist.com. That goes right to my phone as well so I can probably reply quickly if I don't need to be at a computer to answer your question.

Briantist

@sai:

it's the return path where the packets are being sent to the gateway when they shouldn't be.

generally means the netmask is wrong but I am not sure how VIPs (and associated netmask) work in this…

now this is weird:

11:54:47.266968 00:50:8b:cf:a2:6a > 00:30:94:01:e7:90, length 62: (tos 0x0, ttl 63, id 38111, flags [DF], proto: TCP (6), length: 48) 12.34.56.24.22 > 12.34.56.241.3490: S, cksum 0xbcfc (correct), 3571569917:3571569917(0) ack 2188962038 win 5840 <mss 1460,nop,nop,sackok="">11:54:49.492704 00:50:8b:cf:a2:6a > 00:20:ed:91:f7:04, length 62: (tos 0x0, ttl 63, id 1468, flags [DF], proto: TCP (6), length: 48) 12.34.56.24.22 > 12.34.56.241.3479: S, cksum 0x6e76 (correct), 2180526778:2180526778(0) ack 2586252549 win 5840 <mss 1460,nop,nop,sackok="">2 consecutive packets, both from 12.34.56.24 both to 12.34.56.241 but (looking at the MAC address ) one goes to the gateway (ie the T1 modem) the other goes to the correct server.

all I can say is "wtf?". this problem really needs a guru</mss></mss>

I didn't see your edit until now. That is weird; I didn't notice it before. I also checked the original packet capture data to make sure I didn't accidentally paste an incorrect MAC address, and I have confirmed that I did not (what you're seeing is correct). This makes it all the more weird though; I thought I had a consistent, repeatable issue here (and I do, kind of), but this one little packet is seriously making me wonder… I think it increases the likelihood that this problem is something I've done (whether it's in pfSense or not) to cause this problem. I can't think of what that might be though. Again, the help is really appreciated. Thanks everyone.

GruensFroeschli

Sorry for not writing back sooner.
I'm having some problems with faulty hardware (part of my network-test-enviroment just died) and i havent had the time to replace it.
I'll be in holiday for a week now.
I hope the replacement parts i ordered are here when i get home.

Briantist

That sucks, sorry to hear about your hardware. Thanks for the update though, I've been checking the thread multiple times per day.

Briantist

GruensFroeschli, please tell me you haven't forgotten about me! :'(

Anyone have any ideas? Any experiences with this?

GruensFroeschli

No i havent forgotten about you.
In fact i'm working on it right now ;)

But i think i've run into another problem with NAT.
Trying to reproduce it right now >_<

Will probably write back later today. (if i dont go crazy)

GruensFroeschli

Ok i think i tried everything.
But i havent been able to reproduce your problem.

Here is what i did:


		(WAN - public IP)
		ADSL-modem/router
		(LAN - 192.168.20.1/29)
		   |
		   |
192.168.20.4/29	   |
test-client-----switch--------------------------(WAN - 192.168.20.5/29)
		   |				pfSense2
		   |				(LAN - 192.168.40.1/24)
		   |				   |
		   |				   |
	(WAN - 192.168.20.6/29)			   |
	pfSense1 (OPT1 - 192.168.40.2/24)--------switch----------test-client/server
	(LAN - 10.0.0.1/24)					192.168.40.200/24
		   |
		   |
		server
		10.0.0.10/24

I can access the server from the 192.168.20.4 test-client as expected if i connect to 192.168.20.6.
I can access the server as well if i connect to 192.168.20.5

What you described is, that if the gateway on OPT1 is set you can no longer access the server from (in my case) the 192.168.40.x/24 range.
This worked for me.

I'm not sure what the problem in your case could be >_<

pfSense1(main)_OPT_config.JPG
pfSense1(main)_OPT_config.JPG_thumb
pfSense1(main)_port_forwards.JPG

pfSense1(main)_FW_WAN.JPG
pfSense1(main)_FW_WAN.JPG_thumb
pfSense1(main)_FW_OPT.JPG
pfSense1(main)_FW_OPT.JPG_thumb

pfSense2_port_forwards.JPG_thumb

pfSense2_FW_WAN.JPG_thumb

GruensFroeschli

Schnittstelle: 192.168.40.200 –- 0x3
Physikalische Adresse . . . . . . : 00-03-25-09-91-19 <<–- test-client/server
Internetadresse Physikal. Adresse Typ
192.168.40.1 00-02-44-8f-03-ae dynamisch <<–- Gateway
192.168.40.2 00-0d-b9-05-67-25 dynamisch <<–- OPT-interface
@OK:

22:54:31.781241 00:03:25:09:91:19 > 00:0d:b9:05:67:25, ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 128, id 56430, offset 0, flags [DF], proto: TCP (6), length: 48) 192.168.40.200.1596 > 192.168.40.2.80: S, cksum 0x30be (correct), 1713509472:1713509472(0) win 65535

@STRANGE:

22:54:31.782478 00:0d:b9:05:67:25 > 00:02:44:8f:03:ae, ethertype IPv4 (0x0800), length 62: (tos 0x0, ttl 127, id 31917, offset 0, flags [DF], proto: TCP (6), length: 48) 192.168.40.2.80 > 192.168.40.200.1596: S, cksum 0x7865 (correct), 1117681065:1117681065(0) ack 1713509473 win 65535

@OK:

22:54:31.782905 00:03:25:09:91:19 > 00:0d:b9:05:67:25, ethertype IPv4 (0x0800), length 60: (tos 0x0, ttl 128, id 56431, offset 0, flags [DF], proto: TCP (6), length: 40) 192.168.40.200.1596 > 192.168.40.2.80: ., cksum 0xa461 (correct), 1:1(0) ack 1 win 65535

@OK:

22:54:31.819768 00:03:25:09:91:19 > 00:0d:b9:05:67:25, ethertype IPv4 (0x0800), length 591: (tos 0x0, ttl 128, id 56432, offset 0, flags [DF], proto: TCP (6), length: 577) 192.168.40.200.1596 > 192.168.40.2.80: P, cksum 0x6236 (correct), 1:538(537) ack 1 win 65535

@STRANGE:

22:54:31.822462 00:0d:b9:05:67:25 > 00:02:44:8f:03:ae, ethertype IPv4 (0x0800), length 299: (tos 0x0, ttl 127, id 4765, offset 0, flags [DF], proto: TCP (6), length: 285) 192.168.40.2.80 > 192.168.40.200.1596: P, cksum 0xc9bd (correct), 1:246(245) ack 538 win 64998

@OK:

22:54:31.945686 00:03:25:09:91:19 > 00:0d:b9:05:67:25, ethertype IPv4 (0x0800), length 60: (tos 0x0, ttl 128, id 56435, offset 0, flags [DF], proto: TCP (6), length: 40) 192.168.40.200.1596 > 192.168.40.2.80: ., cksum 0xa248 (correct), 538:538(0) ack 246 win 65290

Obviously i can reproduce that traffic is being sent to the wrong MAC.

But i'm wondering why it's working here…..

GruensFroeschli

Ok i went at it with wireshark again. (see attachment)
The downloaded content is the page on http://psymia.mine.nu
Everything seems to be in order…. (see frame 6)

But now i'm wondering why the capture from pfSense itself differs from the capture with wireshark.

??? ??? ???

test_capture.pcap.txt

Briantist

GruensFroeschli, thanks so much for putting time into this. I'm sorry I haven't been able to do anything with it; I had to move suddenly, and things have been really crazy. I have had no time whatsoever to devote to this, and it might be a while before I can try again. I will resume working on this problem though, and I'll let you know how it turns out. Thanks again!

eri--

Can any of you describe what the issue is, if any, so i can give a looka t it?

Briantist

ermal, I'm confused. What information do you need that is not in the thread? I think we've been really descriptive.