[SOLVED] Do not log TCP packets with flags TCP:RA / TCP:PA etc.

mcury · Jan 1, 2024, 2:51 PM

That is a good question, how long you been working with firewalls? @bmeeks has been in the field for many many a year ;) hehe And myself as well.. When you have to look at logs of this stuff, you look for ways to clean them up and only have stuff your interested in ;)

More than 10 years, I guess I'm used to suffer when checking logs

johnpoz · Jan 1, 2024, 2:57 PM

@mcury 10 years - just a baby then, heheh that does look pretty quiet - that is just non Syn traffic looks like. What about UDP noise? You doing any filtering by source IP that your not logging?

I block most if not all of the scanners, like shodan, etc. I also limit traffic by geoip on who can actually hit my port forwards.. Now I currently log all this traffic, if it is syn only..

There are multiple was to reduce the noise that is logged..

mcury · Jan 1, 2024, 3:18 PM

@johnpoz said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

10 years - just a baby then

Yeap, I started with Cisco routers and switches and around 15 years ago, and around 10 years ago it was just firewalls, Cisco ASA, Fortigate, Checkpoint, Palo Alto and Sonicwall, never looked back but we never forget the routing stuff =)

@johnpoz said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

that is just non Syn traffic looks like.

In the pic above, I was just filtering just TCP, but excluding SYN.. let me include UDP in it. Here it goes:

@johnpoz said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

What about UDP noise? You doing any filtering by source IP that your not logging?

Edit: Logging all TCP but TCP:S and all UDP traffic that hit both WANs, disabled packets that are blocked by the implicit default block rule.

johnpoz · Jan 1, 2024, 3:15 PM

@mcury said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

and all UDP traffic that hit both WANs

You might want to limit that to interesting ports if your goal is trim down the amount of noise your logging. My interesting ports is a pretty long list, but it does reduce some of the noise not logging every port ;)

mcury · Jan 1, 2024, 3:18 PM

@johnpoz said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

You might want to limit that to interesting ports if your goal is trim down the amount of noise your logging. My interesting ports is a pretty long list, but it does reduce some of the noise not logging every port ;)

I'll start preparing that list now.. =)

johnpoz · Jan 1, 2024, 3:32 PM

@mcury here is my list.. It prob way longer than need/should be but I had does some looking to what ports to put in there while back..

2:3 Entry added Thu, 17 Oct 2019 06:17:40 -0500
7 Entry added Thu, 17 Oct 2019 06:17:40 -0500
9 Entry added Thu, 17 Oct 2019 06:17:40 -0500
13 Entry added Thu, 17 Oct 2019 06:17:40 -0500
17 Entry added Thu, 17 Oct 2019 06:17:40 -0500
19:23 Entry added Thu, 17 Oct 2019 06:17:40 -0500
37:38 Entry added Thu, 17 Oct 2019 06:17:40 -0500
42 Entry added Thu, 17 Oct 2019 06:17:40 -0500
49 Entry added Thu, 17 Oct 2019 06:17:40 -0500
67:69 Entry added Thu, 17 Oct 2019 06:17:40 -0500
80 Entry added Thu, 17 Oct 2019 06:17:40 -0500
88 Entry added Thu, 17 Oct 2019 06:17:40 -0500
111:113 Entry added Thu, 17 Oct 2019 06:17:40 -0500
120 Entry added Thu, 17 Oct 2019 06:17:40 -0500
135:139 Entry added Thu, 17 Oct 2019 06:17:40 -0500
158 Entry added Thu, 17 Oct 2019 06:17:40 -0500
161:162 Entry added Thu, 17 Oct 2019 06:17:40 -0500
177 Entry added Thu, 17 Oct 2019 06:17:40 -0500
192 Entry added Thu, 17 Oct 2019 06:17:40 -0500
199 Entry added Thu, 17 Oct 2019 06:17:40 -0500
207 Entry added Thu, 17 Oct 2019 06:17:40 -0500
217 Entry added Thu, 17 Oct 2019 06:17:40 -0500
363 Entry added Thu, 17 Oct 2019 06:17:40 -0500
389 Entry added Thu, 17 Oct 2019 06:17:40 -0500
402 Entry added Thu, 17 Oct 2019 06:17:40 -0500
407 Entry added Thu, 17 Oct 2019 06:17:40 -0500
427 Entry added Thu, 17 Oct 2019 06:17:40 -0500
434 Entry added Thu, 17 Oct 2019 06:17:40 -0500
443 Entry added Thu, 17 Oct 2019 06:17:40 -0500
445 Entry added Thu, 17 Oct 2019 06:17:40 -0500
464 Entry added Thu, 17 Oct 2019 06:17:40 -0500
497 Entry added Thu, 17 Oct 2019 06:17:40 -0500
500 Entry added Thu, 17 Oct 2019 06:17:40 -0500
502 Entry added Thu, 17 Oct 2019 06:17:40 -0500
512:515 Entry added Thu, 17 Oct 2019 06:17:40 -0500
517:518 Entry added Thu, 17 Oct 2019 06:17:40 -0500
520 Entry added Thu, 17 Oct 2019 06:17:40 -0500
539 Entry added Thu, 17 Oct 2019 06:17:40 -0500
559 Entry added Thu, 17 Oct 2019 06:17:40 -0500
593 Entry added Thu, 17 Oct 2019 06:17:40 -0500
623 Entry added Thu, 17 Oct 2019 06:17:40 -0500
626 Entry added Thu, 17 Oct 2019 06:17:40 -0500
631 Entry added Thu, 17 Oct 2019 06:17:40 -0500
639 Entry added Thu, 17 Oct 2019 06:17:40 -0500
643 Entry added Thu, 17 Oct 2019 06:17:40 -0500
657 Entry added Thu, 17 Oct 2019 06:17:40 -0500
664 Entry added Thu, 17 Oct 2019 06:17:40 -0500
682:689 Entry added Thu, 17 Oct 2019 06:17:40 -0500
764 Entry added Thu, 17 Oct 2019 06:17:40 -0500
767 Entry added Thu, 17 Oct 2019 06:17:40 -0500
772:776 Entry added Thu, 17 Oct 2019 06:17:40 -0500
780:782 Entry added Thu, 17 Oct 2019 06:17:40 -0500
786 Entry added Thu, 17 Oct 2019 06:17:40 -0500
789 Entry added Thu, 17 Oct 2019 06:17:40 -0500
800 Entry added Thu, 17 Oct 2019 06:17:40 -0500
814 Entry added Thu, 17 Oct 2019 06:17:40 -0500
826 Entry added Thu, 17 Oct 2019 06:17:40 -0500
829 Entry added Thu, 17 Oct 2019 06:17:40 -0500
838 Entry added Thu, 17 Oct 2019 06:17:40 -0500
902:903 Entry added Thu, 17 Oct 2019 06:17:40 -0500
944 Entry added Thu, 17 Oct 2019 06:17:40 -0500
959 Entry added Thu, 17 Oct 2019 06:17:40 -0500
965 Entry added Thu, 17 Oct 2019 06:17:40 -0500
983 Entry added Thu, 17 Oct 2019 06:17:40 -0500
989:990 Entry added Thu, 17 Oct 2019 06:17:40 -0500
996:1001 Entry added Thu, 17 Oct 2019 06:17:40 -0500
1007:1008 Entry added Thu, 17 Oct 2019 06:17:40 -0500
1012:1014 Entry added Thu, 17 Oct 2019 06:17:40 -0500
1019:1051 Entry added Thu, 17 Oct 2019 06:17:40 -0500
1053:1060 Entry added Thu, 17 Oct 2019 06:17:40 -0500
53 Entry added Thu, 17 Oct 2019 12:07:49 -0500
123 Entry added Sat, 11 Apr 2020 02:33:04 -0500
33434 Odd port from pfsense forums

Wow from 2019, man time flies.. Doesn't seem like that long ago that I did that ;)

m0urs · Jan 1, 2024, 3:40 PM

@bmeeks
Unfortunately it seems not to work that way. I still get packets logged with these flags set:

Do not get confused, I named my self created rule "Default blocking rule", but the ID is my own rule and not the pfSense default rule.

Here is the rule I created:

What am I doing wrong?

mcury · Jan 1, 2024, 3:46 PM

@johnpoz Wol, that is indeed a long list, I was thinking about ports:

7 WOL common used
9 WOL default
53 DNS
67:68 DHCP
80 QUIC
88 Kerberos
123 NTP
443 QUIC
500 IPsec
514 Syslog
1194:1198 Common OpenVPN ports..
4500 NAT-T

mcury · Jan 1, 2024, 3:44 PM

@m0urs said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

What am I doing wrong?

Did you disable this ?

johnpoz · Jan 1, 2024, 3:45 PM

@mcury yeah its a bit long.. I went a bit overboard when was looking into ports that might be good to log.. I could prob trim it down.. But I really don't see much udp traffic even with that long list.

Yeah default deny logging is off

m0urs · Jan 1, 2024, 3:46 PM

@mcury said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

Did you disable this ?

Yes.

As I said: The logging comes from my own created rule and not from the pfSense default blocking rule.

mcury · Jan 1, 2024, 4:00 PM

@m0urs said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

The logging comes from my own created rule and not from the pfSense default blocking rule.

I'm trying to replicate this here, but now filtering TCP:S only, in my LAN networks.

mcury · Jan 1, 2024, 4:41 PM

Are you using that "Invert match" option for source or destination in that rule ? So far, I'm unable to replicate this behavior here but I'm not using those options.

m0urs · Jan 1, 2024, 4:49 PM

@mcury No, I do not use "Invert Match". That is my definition, together with that TCP Flags option mentioned above:

m0urs · Jan 1, 2024, 4:52 PM

@mcury ah, maybe this does not work if protocol set to "Any"? I will try with Protocol set to "TCP" ...

m0urs · Jan 1, 2024, 5:04 PM

@mcury

No, unfortunately that did not change anything. These kind of packets are still logged by that rule:

You you explain me a bit more, what how this "TCP flag" setting is working? I still did not get it. What exactly is meant by "set" and "out of"?

mcury · Jan 1, 2024, 5:36 PM

@m0urs said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

What exactly is meant by "set" and "out of"?

https://docs.netgate.com/pfsense/en/latest/firewall/configure.html#tcp-flags

m0urs · Jan 1, 2024, 5:59 PM

@mcury

"By default, new pass rules for TCP only check for the TCP SYN flag to be set, out of a possible set of SYN and ACK."

Hm, so I would say that I just need to create a normal rule without any options enabled in "TCP flag"? In this case I do get a logging entry if there is something blocked with SYNC flag and no more logging entries for all the other packtes?

That would be what I wanted?

Update: It says "new PASS rules", but I have a REJECT rule?

mcury · Jan 1, 2024, 6:00 PM

@m0urs said in Do not log TCP packets with flags TCP:RA / TCP:PA etc.:

@mcury

"By default, new pass rules for TCP only check for the TCP SYN flag to be set, out of a possible set of SYN and ACK."

Hm, so I would say that I just need to create a normal rule without any options enabled in "TCP flag"? In this case I do get a logging entry if there is something blocked with SYNC flag and no more logging entries for all the other packtes?

That would be what I wanted?

Yes, try that and report back.
Other option would be to create a new rule below that one, and set flags to all but SYN, and set to no log.

m0urs · Jan 1, 2024, 6:26 PM

@mcury I had a look into the Packet Filter rules generated by pfSense.

Could it be that these options are only used for PASS rules but not for BLOCK rules?

Here is the output for that rule either with PASS:

[2.7.2-RELEASE][root@router02.urs.lan]/root: pfctl -vvsr | grep "33276"

@177 pass in log quick on igb2.20 inet all flags S/SA keep state label "USER_RULE" label "id:1704133276" ridentifier 1704133276

and with BLOCK:

[2.7.2-RELEASE][root@router02.urs.lan]/root: pfctl -vvsr | grep "33276"

@177 block drop in log quick on igb2.20 inet all label "USER_RULE" label "id:1704133276" ridentifier 1704133276