Ports, rules, NAT
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So looks to me the client sent syn S and then server sent back syn,ack S.
But then the client says no thanks with a R
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Sorry, I am not a network person.
Are we saying this is backend server dropping/rejecting or that things look ok here?
Both IIS box and Exchange will reboot shortly for completeness.
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Apologies, didn't see your latter reply
Ok so it's IIS still saying it's not happy - at least I have a focus area.
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Im not sure who the 138.x box is, but he is the client as he sends the syn... The server at 192.x box answers with syn,ack - this is normal start of a conversation.. But then the 138.x box sends R (RST) which is basically a F Off sort of thing..
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Strange that the client is sending the reset. There are very limited circumstances for that to happen, and I don't see any that I know of applying here.
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Just to be clear, this happens if I send the NAT to the IIS relay OR the Exchange box directly.
This does NOT affect clients on the LAN or any other VLAN, only requests that come in through the PfSense box.
The IIS box has it's firewall disabled for a moment, but this should not be it as internal clients work.
Both IIS and Exchange have been rebooted.
While I want to rule out AV because internal clients are working, I am happy to remove/disable it for now.
As an FYI - this is my home lab, not a production system so this is not massively critical, but a PITA nonetheless.
Something else that may or may not be relevant (I dont think it is, but i'l include it anyway).
About 2 days ago (probably some 6-8 hours before this started) I moved my domains DNS from DynDNS to CloudFlare - I have tried with and without proxied DNS, neither matter, however because the port shows as open on my public IP directly, I dont believe this to be related, though I am more than happy to be proven wrong.
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If you have time, I'd love to see one more test run with the Level of Detail set to high so I can see the packet timestamp values.
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17:16:46.428834 IP 192.168.1.35.443 > 138.201.87.102.48424: tcp 0
17:16:46.469427 IP 138.201.87.102.48424 > 192.168.1.35.443: tcp 0
17:16:46.522427 IP 192.168.1.35.443 > 138.201.87.102.61203: tcp 0
17:16:47.487447 IP 192.168.1.35.443 > 138.201.87.102.61529: tcp 0
17:16:47.886778 IP 192.168.1.35.443 > 138.201.87.102.61068: tcp 0
17:16:48.538018 IP 95.216.36.80.35970 > 192.168.1.35.443: tcp 0
17:16:48.538399 IP 192.168.1.35.443 > 95.216.36.80.35970: tcp 0
17:16:48.642150 IP 82.132.247.36.52308 > 192.168.1.35.443: tcp 55
17:16:48.645073 IP 192.168.1.35.443 > 82.132.247.36.52308: tcp 109
17:16:48.649273 IP 82.132.247.36.52308 > 192.168.1.35.443: tcp 46Guys - thank you for the help, really, it means a lot to know there are people out there willing to spend their weekends trying to help others.
I do believe 'CloudFlare' are to blame, I removed all of the DNS proxy connections once more and it's working again.
Does the above negate you wanting a further run?
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if it is working for you now, i'm happy enought
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If you're satisfied that it's working and you've found the cause then no, you don't need to do that other test run.
I'm still curious as to what was really going on. I'm not sure how a DNS proxy issue would cause your client to send a RST. Where were these DNS proxy connections configured? Via some Cloudflare GUI or is this something you're doing on the pfSense box?
If this was indeed a remote issue then that would explain why it was working fine until one day when it wasn't.
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You realise I will most likely be sticking around finding other guides and helping where I can, and no doubt I will have more questions.
So far though I really do like PfSense.
I am doing more with it within 2 months than I ever thought I would do with any networking product, I even sold my router - which by the way I really liked too (Netgear Nighthawk R7000)
CloudFlare can proxy DNS requests, so assuming my website (or in this case, webmail) points to 81.x.x.x, CloudFlare makes it their own IP, so it looks like 101.x.x.x, while my IP had the ports open and CloudFlare did too, it didnt seem to be relaying HTTPS connections to me, but instead to itself - I found an article on their site about this, something to do with how SSL works with their certificates - this would also explain why I was not seeing the traffic hit the box - which by the way I now see when someone connects to 443.
Phew... nightmare.
Apologies for the wild chase there, but just having someone else there helped me to find the issue.
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Glad we could help.
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I want to complete this topic by also stating I now know why my DNS proxy was re-enabled (sometimes we overthink things).
In PfSense DynamicDNS is an option to enable Proxying DNS - this turned it back on after I disabled it on CloudFlare directly. Makes sense why it was working then stopped. Using this option is great, but when you need HTTP/S traffic to be directed, directly and a given IP you must disable proxying (I can't find their guide right now, I've lost it already).
Here is the article linked from within PfSense that I obviously missed
https://blog.cloudflare.com/announcing-virtual-dns-ddos-mitigation-and-global-distribution-for-dns-traffic/
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I just wanna know why your IP is scanning me like crazy... :P Or are you behind some kind of carrier NAT?
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Those IPs are nothing to do with me, they are also hitting me.
They are based in Germany and Finland, I am not, nor do I have any services from Germany or Finland.
Using the link above posted by @kiokoman they are on an abuse list, therefore they are likely bots or malicious servers.
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@Rod-It said in Ports, rules, NAT:
138.201.87.102
That is the IP of the device you were saying wasn't working ;)
In your sniffs.
17:16:46.469427 IP 138.201.87.102.48424 > 192.168.1.35.443: tcp 0
17:16:46.522427 IP 192.168.1.35.443 > 138.201.87.102.61203: tcp 0 -
I never said that IP wasn't working, you have a snip of a packet capture as asked for. Any external IPs within are purely coincidental.
I didnt validate any external IPs to the forum of my own.
I know my topic was a little confusing at times, but I never stated any specific public IP I was using.
If anything I stated no external IPs were getting in, but some were frequently trying - and those are likely what you see from the logs.
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Ah well that makes more sense why its sent a R then ;)
I would block those IPs from talking to your services. Especially if they are on block lists.
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I have, the poster above, like yourself believed that IP belonged to me - but none of them do :)
Side question based on the new addition to the topic though, without SquidGuard or any other type of filtering, can PF block known malicious or bad IPs?
Also, if there is a way I can mark this as resolved, please let me know and I will do so.
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you can use suricata/snort for example
