DNS Resolver doesn't work with my university domain.

johnpoz

@fandangos so you on your sniff you show traffic leaving pfsense where the source is not 123, and they get no answers either. Or did you disable their ntp servers and just use your work around..

Just want you to have as much info as possible when complaining to your isp. A good sniff showing traffic with source port 123 and other with other source port that your not getting any answers to anything that you send to port 123 ntp..

Fandangos

@johnpoz

not sure if I follow.
I don't know what those TCP packets are. I just pasted those to show that right after the UDP 123 request there's nothing comming back at 123.

My workaround uses wget, there's nothing of NTP there, it just gets the date set by google.

Now I've found a docker container on Unraid called NTP that by the description uses chrony:
https://hub.docker.com/r/cturra/ntp

installed it and used

pool.ntp.org, time.google.com

as NTP_SERVERS

Log from this docker container:

2022-09-07T14:43:54Z chronyd version 4.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP -SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 -DEBUG)
2022-09-07T14:43:54Z Disabled control of system clock
2022-09-07T14:43:54Z Could not read valid frequency and skew from driftfile /var/lib/chrony/chrony.drift
2022-09-07T14:43:59Z Selected source 143.107.229.210 (pool.ntp.org)
2022-09-07T14:43:59Z System clock wrong by 74.923575 seconds
2022-09-07T14:43:59Z Could not step system clock
2022-09-07T14:44:01Z System clock wrong by 74.923624 seconds

So I set my unraid box as ntp server on pfsense and look at this:

10.27.33.198 is my unraid box.

So... I'm lost, the docker is able to access the NTP pool but Pfsense and unraid itself is not?

Sep  7 11:58:53 Tower root: Stopping NTP daemon...
Sep  7 11:58:54 Tower ntpd[1525]: ntpd 4.2.8p15@1.3728-o Fri May 21 19:02:16 UTC 2021 (1): Starting
Sep  7 11:58:54 Tower ntpd[1525]: Command line: /usr/sbin/ntpd -g -u ntp:ntp
Sep  7 11:58:54 Tower ntpd[1525]: ----------------------------------------------------
Sep  7 11:58:54 Tower ntpd[1525]: ntp-4 is maintained by Network Time Foundation,
Sep  7 11:58:54 Tower ntpd[1525]: Inc. (NTF), a non-profit 501(c)(3) public-benefit
Sep  7 11:58:54 Tower ntpd[1525]: corporation.  Support and training for ntp-4 are
Sep  7 11:58:54 Tower ntpd[1525]: available at https://www.nwtime.org/support
Sep  7 11:58:54 Tower ntpd[1525]: ----------------------------------------------------
Sep  7 11:58:54 Tower ntpd[1527]: proto: precision = 0.043 usec (-24)
Sep  7 11:58:54 Tower ntpd[1527]: basedate set to 2021-05-09
Sep  7 11:58:54 Tower ntpd[1527]: gps base set to 2021-05-09 (week 2157)
Sep  7 11:58:54 Tower ntpd[1527]: Listen normally on 0 lo 127.0.0.1:123
Sep  7 11:58:54 Tower ntpd[1527]: Listen normally on 1 br0 10.27.33.198:123
Sep  7 11:58:54 Tower ntpd[1527]: Listen normally on 2 lo [::1]:123
Sep  7 11:58:54 Tower ntpd[1527]: Listening on routing socket on fd #19 for interface updates
Sep  7 11:58:54 Tower ntpd[1527]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Sep  7 11:58:54 Tower ntpd[1527]: kernel reports TIME_ERROR: 0x41: Clock Unsynchronized
Sep  7 11:58:54 Tower root: Starting NTP daemon:  /usr/sbin/ntpd -g -u ntp:ntp
Sep  7 12:00:17 Tower ntpd[1527]: receive: Unexpected origin timestamp 0xe6c33036.73536c7b does not match aorg 0000000000.00000000 from server@216.239.35.12 xmt 0xe6c33081.7014ee6e

10.27.33.1 is the pfsense router.

johnpoz

@fandangos

see here

11:08:25.172578 IP ***.***.***.***.123 > 162.159.200.1.123: UDP, length 48

That is your IP talking to that 162, see the .123 is the port your talking from the "source" port.. and then the .123 on the 162 address is the "destination" port

If you notice in my traffic, that 69 address is mine the source port is 23455, and the destination is 123..

When traffic is natted through pfsense the source port is almost always changed.. This is how napt (network address port translation) works.

So you could have your machine 192.168.1.100:X talking to 8.8.8.8:443 when pfsense nats it to your public IP it would be like this

Your public IP 1.2.3.4:Y going to 8.8.8.8:443

Its common for many ntp clients to use source port 123, pfsense would use that or should - here for example is client on my network talking to through pfsense to my ntp server.. Since they are on different vlans. See how its source port 123 to destination port 123

Its a possibility that your isp is blocking traffic that has a source port of 123, because the return traffic to that would be to 123.. So it would be good to see if you still don't get answers to ntp with the source port is not 123..

Any client behind pfsense trying to talk to ntp out on the internet, be it using 123 or not would be natted on pfsense to some other source port.

Which if your saying no ntp client works behind pfsense, that its most likely not the case - but its good to have that info to tell/show the ISP when you complain.

Fandangos

@johnpoz

I'm not so sure anymore that my ISP is blocking it.

root@Tower:~# ntpq
ntpq> v
ntpq 4.2.8p15@1.3728-o Fri May 21 19:02:16 UTC 2021 (1)
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 LOCAL(0)        .LOCL.          10 l   55   64    1    0.000   +0.000   0.000
+time2.google.co .GOOG.           1 u   42   64    1  137.169   -6.854   2.481
*a.st1.ntp.br    .ONBR.           1 u   45   64    1   11.026   -4.679   1.775
 lrtest2.ntp.ifs 143.107.229.211  2 u   42   64    1   18.545   -2.760   3.131
 time.cloudflare 10.221.8.4       3 u   41   64    1   18.712   +2.339   3.138
ntpq>

using:
time.google.com
a.st1.ntp.br
0.br.pool.ntp.org
pool.ntp.org

unraid is able to access it.

Pfsense is not.
Unraid is on my LAN that is accessing WAN behind Pfsense.
That makes zero sense to me.

johnpoz

@fandangos well that points to my theory of them blocking source port 123..

If that is the case, then the simple solution is just point pfsense to that box for its ntp server. Then your other clients could either use pfsense for ntp, or also point to this device.

Fandangos

@johnpoz said in DNS Resolver doesn't work with my university domain.:

If that is the case, then the simple solution is just point pfsense to that box for its ntp server. Then your other clients could either use pfsense for ntp, or also point to this device.

That's what I'm doing.
My question is, does ntpq (out of the box since I changed nothing) uses other port that's not 123?

Or how is it possible that ntpq is able to access those servers and pfsense is not?
If I understand everything so far, it is using port 123, or at least it should be.

johnpoz

@fandangos it is very very common for ntp to use source of 123.. Its possible that some ntp clients might allow you to change - openntpd might, chrony might for example..

I do not believe there is anyway to change it in pfsense, there sure isn't in the gui, and I do not believe the client they use has anyway to do it.

So the simple solution is pick a box, your nas, whatever this tower box is - something that is on 24/7 and use that as your ntp server. Then just point pfsense to it, all your clients to it - or once you have pfsense syncing ntp to this server you pick to use on your network. Clients could just use pfsense as their ntp source, etc.

But really doesn't matter what source port a box your going to use as your ntp server on your network uses, since pfsense will change the source port to something other than 123 when it nats that traffic to the internet.

stephenw10

If you set an interface (or interfaces) for ntpd to listen on it will also use those for outbound requests. If WAN is not included it will NAT that traffic and change the source port:

WAN 	udp 	172.21.16.10:41229 (192.168.10.1:123) -> 141.95.116.44:123 	MULTIPLE:MULTIPLE 	7 / 7 	532 B / 532 B 	
WAN 	udp 	172.21.16.10:36854 (192.168.10.1:123) -> 201.217.3.85:123 	MULTIPLE:MULTIPLE 	7 / 7 	532 B / 532 B 	
WAN 	udp 	172.21.16.10:49005 (192.168.10.1:123) -> 165.140.142.118:123 	MULTIPLE:MULTIPLE 	7 / 7 	532 B / 532 B 	
WAN 	udp 	172.21.16.10:53482 (192.168.10.1:123) -> 46.165.252.57:123 	MULTIPLE:MULTIPLE 	7 / 7 	532 B / 532 B

Steve

johnpoz

@stephenw10 great idea steve - yup that should do it.

Mine doesn't have it selected - so try that first, that be much easier solution.

Fandangos

@johnpoz

I did a packet capture while trying ntpq on unraid, selected ipv4 and udp only
I'm looking at the log for .123 only

13:22:57.861449 IP ***.**.**.***.33801 > 216.239.35.0.123: UDP, length 48
13:22:57.861500 IP ***.**.**.***.62024 > 143.107.229.210.123: UDP, length 48
13:22:57.879592 IP 143.107.229.210.123 > ***.**.**.***.62024: UDP, length 48
13:22:57.920856 IP 216.239.35.0.123 > ***.**.**.***.33801: UDP, length 48

13:22:59.920620 IP 216.239.35.0.123 > ***.**.**.***.33801: UDP, length 48
13:23:00.861400 IP ***.**.**.***.37425 > 201.49.148.135.123: UDP, length 48

and

13:23:03.861526 IP ***.**.**.***.33801 > 216.239.35.0.123: UDP, length 48
13:23:03.861546 IP ***.**.**.***.62024 > 143.107.229.210.123: UDP, length 48
13:23:03.879777 IP 143.107.229.210.123 > ***.**.**.***.62024: UDP, length 48
13:23:03.920821 IP 216.239.35.0.123 > ***.**.**.***.33801: UDP, length 48
13:23:04.861879 IP ***.**.**.***.37425 > 201.49.148.135.123: UDP, length 48
13:23:04.861897 IP ***.**.**.***.37188 > 200.160.7.186.123: UDP, length 48
13:23:04.872419 IP 200.160.7.186.123 > ***.**.**.***.37188: UDP, length 48
13:23:04.885491 IP 201.49.148.135.123 > ***.**.**.***.37425: UDP, length 48
13:23:05.862358 IP ***.**.**.***.33801 > 216.239.35.0.123: UDP, length 48
13:23:05.862377 IP ***.**.**.***.62024 > 143.107.229.210.123: UDP, length 48
13:23:05.880758 IP 143.107.229.210.123 > ***.**.**.***.62024: UDP, length 48
13:23:05.921698 IP 216.239.35.0.123 > ***.**.**.***.33801: UDP, length 48
13:23:06.862783 IP ***.**.**.***.37425 > 201.49.148.135.123: UDP, length 48
13:23:06.862893 IP ***.**.**.***.37188 > 200.160.7.186.123: UDP, length 48

So I get it, it's not blocked at all.

Fandangos

@stephenw10 said in DNS Resolver doesn't work with my university domain.:

If you set an interface (or interfaces) for ntpd to listen on it will also use those for outbound requests. If WAN is not included it will NAT that traffic and change the source port:

I'm not following anymore.

Are you suggesting creating a virtual interface on pfsense and route traffict trought it?
I don't know how to do it.

oh, you mean just unselect WAN?

johnpoz

@fandangos yeah blocking source port 123 allows them to prevent you from running a ntp server to the public internet. Because into the isp 123 destination is blocked. So they prob are not actually blocking the source port, but destination port of 123 into the isp network, which your on. So when you use 123 as source, the answer would be to destination 123 into the isp network, which they block.

But this blocks your answers from getting to you as well because to answer you the answer uses destination 123

Prob doesn't effect most of their users, because the isp router is prob natting all the isp users traffic and changing the source port, etc. So those users never notice and issue.

Reason you seeing the problem is pfsense using its public wan IP never goes through a nat and uses the common normal source port for ntp of 123

Fandangos

@johnpoz

It's alive!

johnpoz

@fandangos Yeah!!! great all sorted and didn't have to sit on hold with your isp, talking to someone that had no idea what your talking about.. And them telling you we do not block any outbound ports ;)

Fandangos

Can't thank you enough, guys.
Specially John that helped for days until this got figured out, one problem after another.

Thanks a lot! :)))

stephenw10

Wow, that's fun*. So the ISP is blocking the udp traffic with source port 123 because that's easier than actually using a stateful firewall?!

Fandangos

@stephenw10

Guess so, it's weird but I always had this problem. To be honest, I'm not sure why it started working for my unraid box.
It didn't a few months ago when I looked into this.

johnpoz

@fandangos glad could be of help.. Always fun getting to the actual root of a problem..

johnpoz

@stephenw10 nothing saying the security guy at isps have to be the sharpest crayon in the box ;) heheh

Our users don't need 123 inbound, only out. Never coming to think that 123 is the default/common source port as well for ntp. And they prob don't get many complaints, because most of their users are prob using the isp router and all their devices are behind a nat so would never see the problem to complain about it.

@Fandangos if you ever just sitting around hmmm, what could I do that would be painful - you could try calling your isp and point out to them the problem they have ;)

Gertjan

@johnpoz said in DNS Resolver doesn't work with my university domain.:

Reason you seeing the problem is pfsense using its public wan IP never goes through a nat and uses the common normal source port for ntp of 123

You mean :
When I use a modem device, and one PC hooked up to it, using for example PPPOE, this PC won't be able to 'ntp' neither ?
I know, this set up doesn't exist any more these days, but was quiet common in the old days.

I would like to understand what the reason for the ISP is to block this port 123.
ntp is a very low bandwidth service.
Router firewalls like pfSense can handle often TLS related functions, DNSSEC is just one of them, and using the correct time is not some kind of option.
So it should go back into it's LAN, to ask a NTP service (server), and that one goes back out to the net to sync ?
Strange ....