Delete state, Reject & Block rules work perfectly fine
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I still havent got to the bottom of where this problem stems from though
what problem?
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They should….for that specific rule and not the entire state tale ;)
Exactly why states should not be automatically cleared.
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Submit a feature request. It's not a bug.
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I didnt and I dont see any mention of deleting states in numerous online blogs detailing how to do XYZ, nor is it in the pfsense book and I dont see it mentioned often in the forums either. So whether "everyone" knows is a matter of opinion.
https://doc.pfsense.org/index.php/Firewall_Rule_Troubleshooting#Dangling_States
"Did you clear your states?" is asked like 5000 times a week here.
That appears to be the only reference, besides do you know how many references there are to the phrase "Dangling State" in the forums?
Answer is here. http://bfy.tw/6mC
The quick answer is 0 (thats zero) reference to Dangling States in the forums and its certainly not mentioned in many many online how to's in websites & blogs. Thats alot of pfsense firewalls and others out there which can easily be compromised when combined with other methods to gain control of systems & networks.
Its also interesting there is only one link to this page which is here,
https://doc.pfsense.org/index.php/Special:WhatLinksHere/Firewall_Rule_TroubleshootingQuite why you feel the need to exaggerate the fact its refered to 5000 times, I can only go and consult the handbook here: http://pastebin.com/irj4Fyd5
It seems to me the significance of a Dangling State is not recognised or being played down.
The first mention of it captured by the Wayback Machine was on Sun May 17 2009
http://web.archive.org/web/20090501000000*/https://doc.pfsense.org/index.php/Firewall_Rule_TroubleshootingIt seems this problem exists in all versions of pfsense going back to 1.x which explains alot regarding how many times I have been hacked since I started using pfsense 1.2
I think they already have a script for this and use it for scheduled rules. Maybe we just need a "kill all states" button under the edit window screen, allowing you to kill existing states for the current rule.
Heres a test scenario you can do where the scheduled rules dont work which is probably best explained now as a "dangling state" as mentioned by Derelict, but is where the Inward bound wan states are not killed off.
Create your normal rules, in my example I have a Pass everything out rule.
FIrewall:Schedules webpage, Create a schedule that will take place in the future. For now I used 1st June (today), and set the time window for 15mins so if the time was 7am, the schedule would be 07:15 to 07:30.
Firewall:Rules web page select the right interface if you have more than Wan & Lan, and just above your Pass everything out rule create a new rule which Blocks everything out, scroll to the bottom of the edit rule webpage & click the Schedule button and select your time schedule from the drop down.
Save and apply changes.Now go watch a long free youtube video that will run for a few hours.
By now it should be getting closer to 07:15 the time at which the Block Everything rule will kick in.Find out what the ip address is from the interface with the Pass Everything and find out what IP address the youtube stream is coming from, once you have that go to the Diagnostic:States window and look up the youtube IP address, you should see two entries for both directions and they should both say Established : Established, if you have the traffic graphs for the interfaces on your dashboard you should also see the youtube traffic coming In on the Wan and Out on the interface where the device playing the youtube video is playing.
At 07:15am you will see in Firewall:Rules the Block Everything rule has become active as the icon in the Schedule column goes from a greyed out icon to a bold coloured icon indicating its gone from disabled to active. Likewise you can also visit the Firewall:Schedules webpage and see a clock icon next to the 07:15am to 07:30 time span. If you visit the Status: System Log: Firewall webpage, select Firewall tab and then Normal tab and filter on the interface by typing in Lan or whatever your interface is called before clicking the Filter button, any newly established traffic going out will be blocked by your now inforce Block Everything rule, whilst the already established youtube stream carries on unhindered.
You can verify the youtube stream is still active by continuing to watch the film or visit the Diagnostics: States webpage and look up the IP address of the youtube server streaming the film to you that you previously found and see the two states are still present, they maybe in a different location in the list but as long as they both have Established : Established in the state column then the "Dangling State" is letting the traffic through as it will for any malware or virus that is currently in your system and has established a connection with the outside world.
Exactly why states should not be automatically cleared.
Submit a feature request. It's not a bug.
IMO "Dangling States" are a bug as it makes it easy for bad actors & bad programs to get in and out of your system. Another way to look at this is, by asking this question, when is a firewall not a firewall? When it cant clear states down according the rules and/or by the schedules set up.
The fact its mentioned in the docs does not legitimise the problem, it simply acknowledges the problem exists.
The question is, can the dangling states be fixed?
However considering this goes back to pfsense 1.x I can no longer consider pfsense a firewall due to this Dangling State bug, so how many users have been duped and forked out money for something that it isnt?
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Still not a bug. Maybe it could best be described as a limitation. A well-known one at that. You should probably move on to that free firewall that's better than pfSense.
Yes, it would be nice if schedule triggers cleared states for just that rule. Submit a feature request.
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See:
https://forum.pfsense.org/index.php?topic=93336.23
intuitively I would call this behaviour a bug.
I may cite you, Derelict:
" Re: Firewall: Scheduling block game console
« Reply #4 on: May 04, 2015, 02:49:18 am »And all your ssh and other persistent sessions go with it. Yuck."
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They work fine. Like everywhere else, when you set a rule it doesn't affect existing states and they have to be cleared either organically or by force.
Feature request.
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Thats cool man!
Schedule rules doesnt really work if they are actually beeing used :D
Mikrotik here I come :D
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Mikrotik here I come :D
I thought you switched to OPNsense recently…
P.S. Schedule rules do work just fine - the allow ones. (I for one certainly do not want to kill everyone's working connections just because I have been playing with some rules. If desired, I can do that manually once I am done with the work. Not e.g. 30 times in an hour...)
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What you want is pretty irrelevant.
What should happen when running a schedule is another thing and it doesnt work.
Its like captive portal. When the time is up, youre done. No matter what you are doing…
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Still not a bug. Maybe it could best be described as a limitation. A well-known one at that. You should probably move on to that free firewall that's better than pfSense.
Yes, it would be nice if schedule triggers cleared states for just that rule. Submit a feature request.
As this dangling state issue appears in the first instances of pfsense [edit]
it would appear to be an issue with the package bundled with FreeBSD called Packet FIlter which might also be known as the Berkeley Packet Filterhttps://en.wikipedia.org/wiki/Berkeley_Packet_Filter They are two different packages [edit]https://www.freebsd.org/cgi/man.cgi?query=pf&sektion=4&apropos=0&manpath=FreeBSD+10.1-RELEASE
So it would appear at this stage that any stateful firewall on xyzBSD both opensource or commercial has the bug unless specific measures have been taken to address the problem (which I have yet to see advertised in my searches), but the source of the problem still has not been identified [edit]
as it could implicate the Libpcap libraries IF Packet Filter is the same thing as the Berkeley Packet Filter.[edit]WRT to PF ported to other OS's the closest comparison could be considered NetFilter in Linux but is considered more complicated due to it working on sets of rules that work in chains unlike the top down match listing of PF, and Linux has a comparable problem called Dangling Sockets.
The situation is further not helped as Chemlud points out pfctl is broken in this thread
https://forum.pfsense.org/index.php?topic=93336.msg518298#msg518298No problem to me, as long as the -k worked properly, in the pre-2.2 era. But now I have to kill all states to make it really work. Dunno why. Always the states with
re1 tcp routerIP(localIP) -> remoteIP ESTABLISHED…
in the states tab survive the -k procedure.
That's not fair. :-(
Update: selective killing of states with option -k is broken, leaves a lot of states in place, as pointed out above. No way around kicking off all users by killing all their states.
Maybe identify the version where pfctl works at killing selective states would be a work around assuming bugs in the corresponding PF are not too compromising.
I thought you switched to OPNsense recently…
P.S. Schedule rules do work just fine - the allow ones. (I for one certainly do not want to kill everyone's working connections just because I have been playing with some rules. If desired, I can do that manually once I am done with the work. Not e.g. 30 times in an hour...)
It wouldnt make any difference as this problem goes back to early versions of xyzBSD including pfsense 1.x as mentioned above.
Whilst you may not want to kill off one or more peoples active connections, would you say the same if it were some malware/virus/botnet established connection?
I have to say, I'm shocked at the widespread acceptance and such long running measured in years of the Dangling States or Dangling Sockets issue/bugs, no wonder bad actors find it so easy to compromise systems.
I'm beginning to wonder if there is any firewall out there that is capable of performing as requested.
Likewise with what I have discovered above, we cant even expect ESF to fix the problems as its core xyzBSD code unless one or more in ESF also code at the OS/package level? Are there any ESF employees who can code the affected packages?
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Yeah, whole BSD is broken, pf is broken, everyone can hack it on a whim, it's full of viruses and botnets that love the buggy shit, and so we are all doomed… What users want is also irrelevant because it's much better to cut them off instead of letting them do it at proper time.
Another shitty thread waiting for a press of LOCK button.
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You really need to see a shrink mate…
ANY thread you comment is not good enough for you. Something is ALWAYS wrong with the topic, content, OP or just about anything else you might seem to dislike...
Geesus.
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P.S. Schedule rules do work just fine - the allow ones. (I for one certainly do not want to kill everyone's working connections just because I have been playing with some rules. If desired, I can do that manually once I am done with the work. Not e.g. 30 times in an hour…)
So you admit by omission that the Block & Reject dont work. Two out of the three conditions (Pass, Block & Reject) seems to be the majority of the options not working as expected, ergo a bug.
With regard to the whole of BSD is broken, depending on how you view a dangling state, some see it as acceptable, others see it as not acceptable, I fall into the latter and find dangling states not acceptable for the reasons I have previously cited, namely I want a firewall to block traffic irrespective of if its trying to get into a private system or network or out.
Data leakages is not viewed favourably by most businesses so how would CEO's, shareholders and others like it if their [insert whatever private data is important to them and/or you] is leaked all because some dont view a dangling state in xyzBSD as important or as a bug?
As I have said before, you cant legitimise a bug by documenting it. Fortunately this is not just a bug in pfsense code, but is still a bug for anyone who happens to use PF on xyzBSD.
However it would be nice if ESF could come up with a solution to address this problem as I'm sure it would increase their kudos in the firewalling community and earn them more users and revenue. At the same time it would be nice if the PF maintainers could address the problem of dangling states by perhaps introducing a switch which could kill affected states for those instances where a rule has changed on reload and/or by fixing pfctl. As long as the BSD maintainers could do the job, I'm sure it would elevate the status of BSD as a firewalling solution instead of the current what I consider to be a design flaw in PF wrt dangling states.
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IMO "Dangling States" are a bug as it makes it easy for bad actors & bad programs to get in and out of your system. Another way to look at this is, by asking this question, when is a firewall not a firewall? When it cant clear states down according the rules and/or by the schedules set up.
It's working as intended, aka, a feature, not a bug. It doesn't make anything easy because the rules still work, for new connections. It's not like firewall rules change all the time, mostly set in stone except for opening ports.
I'm pretty sure they fixed the scheduling issue. Even with schedules, it's not a security issue, it's a bandwidth issue. People want to block high bandwidth services during the day. If it was a security issue, they'd never open the rules in the first place.
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See:
https://forum.pfsense.org/index.php?topic=93336.23
intuitively I would call this behaviour a bug.
I may cite you, Derelict:
" Re: Firewall: Scheduling block game console
« Reply #4 on: May 04, 2015, 02:49:18 am »And all your ssh and other persistent sessions go with it. Yuck."
Further to this issue where Chemlud states pfctl doesnt work
https://forum.pfsense.org/index.php?topic=93336.msg518298#msg518298
No problem to me, as long as the -k worked properly, in the pre-2.2 era. But now I have to kill all states to make it really work. Dunno why. Always the states with
re1 tcp routerIP(localIP) -> remoteIP ESTABLISHED…
in the states tab survive the -k procedure.
That's not fair. :-(
Update: selective killing of states with option -k is broken, leaves a lot of states in place, as pointed out above. No way around kicking off all users by killing all their states.
I checked the freeBSD bug report and could only find the reports that pfctl wasnt working back in 2006,2007 & 2008.
https://bugs.freebsd.org/bugzilla/buglist.cgi?order=Importance&query_format=advanced&short_desc=pfctl%20-k&short_desc_type=allwordssubstr
So I tried the command pfctl -k network ie pfctl - k 1923.168.1.0/24 and sure enough it does kill the states on the lan side, however as the dangling state is an inward bound wan side state pfctl -k would need to kill the opposite side state in this case the wan side inward bound state.
pfctl -s states gives a dump of states and matches what is seen in the Diagnostic: State webpage but the requirement to get the dangling states cleared up still needs to be addressed.
Having looked at the switches for pfctl commands
https://www.freebsd.org/cgi/man.cgi?query=pfctl(8)&sektion=
One approach might be the use of Anchors…
https://www.freebsd.org/cgi/man.cgi?query=pf.conf&sektion=5&apropos=0&manpath=FreeBSD+10.1-RELEASE#ANCHORSBut I cant see anything in pfctl to handle flushing anchors so the two PF & pfctl seem incomplete as a package.
https://www.freebsd.org/cgi/man.cgi?query=pfctl(8)&sektion=It seems initially working on the basis of existing functionality in PF & pfctl, labels maybe the way to go wrt getting the relevant states on both sides flushed, but then the problem occurs where scheduled rules kick in like the test example I posted earlier so it would not work as they would have different labels thus requiring additional functionality still.
There isnt any easy fix with this problem, so I'm going to have to have a think what would be the best approach, because even if pfctl could delete both the inward and outbound corresponding states it still wouldnt address the scheduled rules kicking in. Searching for states to delete on both sides could be too slow if having to run down a sizable list of rule changes.
Somewhere either in pfsense or in PF/pfctl there would need to be new functionality to address the dangling states issue, but where and what to tackle the problem in a reasonable manner is a tricky one.
IMO "Dangling States" are a bug as it makes it easy for bad actors & bad programs to get in and out of your system. Another way to look at this is, by asking this question, when is a firewall not a firewall? When it cant clear states down according the rules and/or by the schedules set up.
It's working as intended, aka, a feature, not a bug. It doesn't make anything easy because the rules still work, for new connections. It's not like firewall rules change all the time, mostly set in stone except for opening ports.
I'm pretty sure they fixed the scheduling issue. Even with schedules, it's not a security issue, it's a bandwidth issue. People want to block high bandwidth services during the day. If it was a security issue, they'd never open the rules in the first place.
Working by design but I would say a flawed design when considering the issue of dangling states. Where I differ perhaps to others is I consider a bug anything thats not working as the user expects, so I could say the Apply Changes button when making a rule change is a bug as it misleads the user into thinking the new rules are ineffect when they may not be. Thats a dangerous situation to be in with security products, but I could also hilight weaknesses in various AV software as well. Likewise its too easy to say its working as programmed because technically every bug is working as programmed ergo bugs wouldnt exist by the working by design definition would they?
I posted an example earlier this morning where scheduled rules kicking in dont stop existing states from rules no longer in effect.
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Just to add: BEFORE 2.2 (i.e. 2.1.5) flushing the states with pfctl -k IP worked in both directions. I get an email with the states after the scheduled block rule kicks in and the cron job kills the states. Prior to 2.2 the email showed no states at all, after installing 2.2 (fresh nano 386 copy + config file) always the states specified above persisted. Therefore I had to switch the cron job for killing states from pfctl -k to pfctl -F states.
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… why does deleting outward bound states not work, but deleting inbound states does work?
By default pfSense allows all outgoing traffic from firewall host itself (try 'pfctl -sr | grep itself'). So when you delete states firewall rules come into play and those deleted outward bound states are recreated again.
So I tried the command pfctl -k network ie pfctl - k 1923.168.1.0/24 and sure enough it does kill the states on the lan side, however as the dangling state is an inward bound wan side state pfctl -k would need to kill the opposite side state in this case the wan side inward bound state.
There is no need to kill the opposite side states . Even if inbound traffic from the WAN side can reach a host in the LAN the host can't reply.
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@chemlud
It appears by the change of wording a change in behaviour has probably occurred.pfsense 2.1 FreeBSD 8.3 Release
https://www.freebsd.org/cgi/man.cgi?query=pfctl&apropos=0&sektion=8&manpath=FreeBSD+8.3-RELEASE&arch=default&format=html
"Kill all of the state entries originating from the specified host or network. "pfsense 2.2 FreeBSD 10.1 Release
https://www.freebsd.org/cgi/man.cgi?query=pfctl(8)&sektion=
"Kill all of the state entries matching the specified host,network, label, or id."I could interpret 8.3 as including the wan side inbound states as the lan side outbound states would have originated the wan side states.
This could explain the change in behaviour you have observed.
… why does deleting outward bound states not work, but deleting inbound states does work?
By default pfSense allows all outgoing traffic from firewall host itself (try 'pfctl -sr | grep itself'). So when you delete states firewall rules come into play and those deleted outward bound states are recreated again.
I'm working on OPTx interfaces I only use lan to access pfsense everything else is blocked by a rule and I lock everything down so even things like netbios & dns needs an allow rule for each device before it can get out, and things like windows updates are allowed out on a schedule, but yes by default like virtually all fw's in their default settings, allow unrestricted access out from the lan to internet which imo is dangerous,hence why I lock things down.
So I tried the command pfctl -k network ie pfctl - k 1923.168.1.0/24 and sure enough it does kill the states on the lan side, however as the dangling state is an inward bound wan side state pfctl -k would need to kill the opposite side state in this case the wan side inward bound state.
There is no need to kill the opposite side states . Even if inbound traffic from the WAN side can reach a host in the LAN the host can't reply.
The Host can reply because the lan side state are recreated automatically by PF.
Have you tried the pinger test and youtube test on say a scheduled block although it will work with any non-allow ie a disabled, reject or block rule change, provided a wan side inbound state exists when any Allow rule was in effect?
Put it like this, if you did the test, how does the pinger continue to send out pings and how come you can pause and resume the youtube film if the host cant reply when the lan side states have been deleted but not the wan side states? Only when the wan side states have been removed which wont occur if all ready established before a scheduled block rule comes into force, or a blocking rule has been added/changed to/enabled and Apply Changes button clicked?
Nice pic. ;D
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Working by design but I would say a flawed design when considering the issue of dangling states. Where I differ perhaps to others is I consider a bug anything thats not working as the user expects, so I could say the Apply Changes button when making a rule change is a bug as it misleads the user into thinking the new rules are ineffect when they may not be. Thats a dangerous situation to be in with security products, but I could also hilight weaknesses in various AV software as well. Likewise its too easy to say its working as programmed because technically every bug is working as programmed ergo bugs wouldnt exist by the working by design definition would they?
I posted an example earlier this morning where scheduled rules kicking in dont stop existing states from rules no longer in effect.
As designed does not mean as programmed. It's working within spec, as intended, not as written. If you design a wheel to pop off when 100lbs of force is applied and only ever expect 50lbs of force to be applied from normal driving conditions, then someone has a driving condition that causes the wheel to pop off because 100lbs of force so happens to get applied, it's working as intended. The wheel was meant to easily come off under very certain circumstances and those criteria where met.
I do agree that it should properly support killing all existing rules that match a block rule, or possibly any rule for that matter, but my main point is by default all traffic is blocked. If traffic is getting through in the first place, it's because you passed it. Don't pass it, no problem. I've changed my pass rules once in 2 years, not like one needs to worry about getting their blocking rules to work ASAP, unless you're doing something strange, like changing your rules all the time.