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pe1chl
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The predicted demise of "tls-host=" firewall filters is near!

Wed Oct 04, 2023 12:45 pm

Firefox has now started rolling out the implementation of Encrypted Client Hello (ECH) to their users:
https://blog.mozilla.org/en/products/fi ... ted-hello/

This will mean that using firewall filters that use tls-host= (or L7 filters that try to do the same thing) to "block certain websites" will become ineffective for users that use the Firefox browser.

Routers will no longer be able to determine what websites users are visiting, at least not without doing man-in-the-middle decryption of TLS (https). Which is only possible for managed devices in companies, not for random visitors or clients of your ISP.
Filtering by IP address is usually not practical because they change all the time and can be shared between different sites.

So prepare for your Youtube filters to become ineffective!
 
llamajaja
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Re: The predicted demise of "tls-host=" firewall filters is near!

Wed Oct 04, 2023 6:12 pm

Yes, perhaps its time to remove layer 7 .
OR
MT provide a separate cloud service where users can control traffic via Application jajajajajaja !
 
msatter
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Re: The predicted demise of "tls-host=" firewall filters is near!

Wed Oct 04, 2023 9:28 pm

Or just block based on IP or IP address ranges. Just like always because for years we knew this was coming.

You can also block the IP addresses of the DOH servers like I did today when Firefox always want to inform dooh.cloudflare.com that I just started the browser. And yes, I disable DOH in Firefox but they wipe their ar.. with my choice, so I had use the firewall to block that exchange of digital information.
 
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Re: The predicted demise of "tls-host=" firewall filters is near!

Wed Oct 04, 2023 9:37 pm

Or just block based on IP or IP address ranges. Just like always because for years we knew this was coming.

You can also block the IP addresses of the DOH servers like I did today when Firefox always want to inform dooh.cloudflare.com that I just started the browser. And yes, I disable DOH in Firefox but they wipe their ar.. with my choice, so I had use the firewall to block that exchange of digital information.
I just switched to using LibreWolf. tcpdump and lsof inform me that no telemetry gets sent when I open the browser.
 
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Re: The predicted demise of "tls-host=" firewall filters is near!

Wed Oct 04, 2023 9:42 pm

Regarding FF telemetry, this is not helping to turn it off? I disabled everything related to it by searching telemetry in FF about:config.
 
msatter
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:59 am

Till the next itteration where they switch it on again. Better use a third party to be sure that I am still the boss on my own devices.
 
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normis
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 8:28 am

Funny topic. You guys want firefox to be more secure and less secure at the same time :)
 
pe1chl
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 11:12 am

Funny topic. You guys want firefox to be more secure and less secure at the same time :)
Well, the issue is that "secure" can have different definitions depending on the viewpoint. The people at Firefox (and some vocal organizations) consider it "secure" when only the end-user can see what data is on their display. See also the campaign to promote https and deprecate http. The (pre-existing) TLS protocol still exposed the hostname of the connected system, as that wasn't a design consideration at all when it was designed. But this new "security against monitoring" still left the desire to hide that info as well. Which is now done.

Of couse such "security against monitoring" (as a protection of privacy) can be conflicting with security of other aspects, and this now shows. Owners of networks may want to prohibit certain usage, not to peek into the user's behavior but to protect their network against abuse (relative to the intended purpose) or over-use (relative to its limited capacity). That capability has now been removed, and therefore a network may collapse under overload, reducing availability. It may even result in some open WiFi networks closing down because they can no longer afford to provide the service in a way that keeps it usable, or its usage within their terms of service.
 
pe1chl
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 11:14 am

Or just block based on IP or IP address ranges. Just like always because for years we knew this was coming.
The problem is that you cannot block services that run on large CDN or other server farms like Google's in that way.
When you even can find all addresses used by Youtube, you may find that the same addresses are used by Gmail, for example.
 
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 11:50 am

That's exactly what I mean. DoH and better encryption for the users can't be done, while keeping network admin desire to block webpages. And at the same time, the network admin is complaining about telemetry of the browser. He wants to be secure himself, but still wants to spy on his own users :)
 
msatter
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:13 pm

Sorry Normis, I don't want to spy on myself and I don't want to be spied on by others. So DOH is in a internal network a curse and I wrote many times before that DOH is made for war time or for regimes that don't give a sh.. about the rights of their citizen. I seem to live also under that kind of regime in the Netherlands. :-(

I have other means to circumvent that Big TECH/GOV brother is watching me all the time and everywhere.

The problem is that programs/APP can hide their behavior and those are mostly sponsored or even designed by Big TECH/GOV to gather information about you.

I came here this morning to start initiative to generate a IP-address/domain list of known DOH servers that are know by us so a owner of a Mikrotik device can use to block those servers from being reached from the inside of the network.

I block myself only from internal network UDP/TCP 443 and ICMP to those IP addresses. If a owner want to use a DOH client as on the router itself than that is allowed just as using the DOH block list. I think UDP is not being used in DOH, but just be certain.

I use a list that can be imported directly into an addresslist in the router and the list can be dynamic by providing only the domains or a IP-address that is static till the next update. It could be a mixed list and a domain will stay inactive till the IP-address of that domain changes (not tested). The import is done by import and creating a temporary list and then swap that one out with active one so the down time is minimal.

Additions can be suggest here and I will add those to the list which is then published.
 
msatter
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:20 pm

Or just block based on IP or IP address ranges. Just like always because for years we knew this was coming.
The problem is that you cannot block services that run on large CDN or other server farms like Google's in that way.
When you even can find all addresses used by Youtube, you may find that the same addresses are used by Gmail, for example.
....those are sites that you only should touch with a very long set of pliers! The best is to find ASAP alternatives for them or just go back to before they existed.
 
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normis
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:34 pm

Fediverse
 
mbovenka
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:40 pm

....those are sites that you only should touch with a very long set of pliers! The best is to find ASAP alternatives for them or just go back to before they existed.

Which is fine for your own little network, but of course not really an option for those that have actual clients to support.
 
msatter
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:53 pm

I just check if the canary domain is inactive but it it is still there and giving a NXDOMAIN as resolve. So Firefox is clearly not obeying it anymore because they have their head somewhere else all the time.
dig use-application-dns.net

; <<>> DiG 9.16.12 <<>> use-application-dns.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 2132
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;use-application-dns.net.       IN      A

;; Query time: 18 msec
;; SERVER: 192.168.xxx.xxx#53(192.168.xxx.xxx)
;; WHEN: Thu Oct 05 11:37:32 West-Europa (zomertijd) 2023
;; MSG SIZE  rcvd: 52
Tested it with DOH on the default setting. It was not tried to be resolved by Firefox, looking in the log of the local DNS resolver.
Last edited by msatter on Thu Oct 05, 2023 1:51 pm, edited 2 times in total.
 
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normis
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 12:58 pm

Sorry, why should it?
 
llamajaja
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 2:32 pm

I understand both needs.

Its no ones business (ISP, google) etc, to see what I am doing.
On the other hand.....
I may not want my network to be used for destructive social programs such as instagram or facebook etc.......... even if just temporarily aka 6 months.
I have come to the conclusion is that the best way ahead is to ensure vlans separate users/devices networks from each other as required so that if an individual wants to endanger themselves, so be it, but hopefully its limited to that subnet/vlan. A little more difficult to do on WIFI,,,,,,,,,,,,,, as there are not infinite wlans...........
 
pe1chl
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 3:13 pm

Sorry, why should it?
The purpose of the use-application-dns.net domain was to tell Firefox in a network that the network admin does not want the users to use DoH.
The domain is registered on internet and one is supposed to override that in a local static entry with an NXDOMAIN response.
I even asked MikroTik to allow local static entries with NXDOMAIN result, which they implemented. And it worked.

But according to msatter (I did not test it myself yet), now Firefox does not query the domain anymore... sad.
In fact I had planned to find if there was another such domain to tell Firefox not to do the ECH but that seems unlikely then.
 
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Re: The predicted demise of "tls-host=" firewall filters is near!

Thu Oct 05, 2023 4:01 pm

Well, there is also the "Oblivious HTTPS" coming down the pipe:
https://www.ietf.org/archive/id/draft-t ... us-01.html

And it's cousin "Oblivious DNS over HTTPS", that hides client IP from the DoH provider:
https://www.rfc-editor.org/rfc/rfc9230.html

Apple (and Cloudflare) have been supportive of these standards, and upcoming MASQUE proxies, https://blog.cloudflare.com/unlocking-q ... potential/.

So won't be just Mozilla. The doomsday clock for tls-host= continues.
 
llamajaja
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Re: The predicted demise of "tls-host=" firewall filters is near!

Fri Oct 06, 2023 2:29 pm

IP cloud service, what could MT do here, heck even for a small price,,,,,,,,, Normis might even get a raise!!
 
kraal
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Re: The predicted demise of "tls-host=" firewall filters is near!

Fri Oct 06, 2023 4:39 pm

I came here this morning to start initiative to generate a IP-address/domain list of known DOH servers that are know by us so a owner of a Mikrotik device can use to block those servers from being reached from the inside of the network.

I block myself only from internal network UDP/TCP 443 and ICMP to those IP addresses. If a owner want to use a DOH client as on the router itself than that is allowed just as using the DOH block list. I think UDP is not being used in DOH, but just be certain.

I use a list that can be imported directly into an addresslist in the router and the list can be dynamic by providing only the domains or a IP-address that is static till the next update. It could be a mixed list and a domain will stay inactive till the IP-address of that domain changes (not tested). The import is done by import and creating a temporary list and then swap that one out with active one so the down time is minimal.

Additions can be suggest here and I will add those to the list which is then published.
I create such a list to feed an alias on my opnsense box on a daily basis. I do it by scrapping the list of publicly available DoH servers on curl project page, resolving the domains then filtering out the IPs which are "problematic": https://github.com/curl/curl/wiki/DNS-over-HTTPS

This is not a panacea, but it kind of works.
 
kraal
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Re: The predicted demise of "tls-host=" firewall filters is near!

Fri Oct 06, 2023 5:35 pm

Well, there is also the "Oblivious HTTPS" coming down the pipe:
https://www.ietf.org/archive/id/draft-t ... us-01.html

And it's cousin "Oblivious DNS over HTTPS", that hides client IP from the DoH provider:
https://www.rfc-editor.org/rfc/rfc9230.html

Apple (and Cloudflare) have been supportive of these standards, and upcoming MASQUE proxies, https://blog.cloudflare.com/unlocking-q ... potential/.

So won't be just Mozilla. The doomsday clock for tls-host= continues.
Well... Once upon a time, we were in a situation where our DNS requests were sent to our ISP's DNS servers. Their answers were "slow", so google decided to provide 8.8.8.8 in order to speed up DNS requests for our good. People started trusting a company obviously making money by selling it's customers data... Then people started using https for everything, even when it was not needed just because "somebody could intercept the content" (which is absurd from an energy usage and thus ecological standpoint). Meantime google and other companies started providing javascript and fonts and central auth to websites in order to "make things easier". Then the fear of being blocked and spied by an ISP, employer, government raised and according to some people the solution became DoH and paid VPNs... which are services mostly owned by big corps located in the USA. Next we have ECH coming in order to make sure that only the clients and server sides will know what url is requested, for the sake of privacy. What a convenient way to hide services allowing potential data leaks... "nobody will be able to trace you" (nor be able to trace what applications are doing under the hood). Now oblivious http and DoH are down the road to make people think that they are even better protected (by another layer of centralization and thus another means to correlate behavior and data.)

Some may pretend that all this is an improvement, I don't. I strongly believe that having to look for data at an ISP, then looking at tens of places is ways more complicated and time consuming than having such centralization. People fear their ISP and government and as a result entrust their privacy to US-based enterprises which are legally obligated to provide information on demand to their government... but which are using this information to have more control over the users. Call me a fool but IMHO people are ignorant and short-sighted.

Security and convenience are opposite notions, any form of centralization is a potential risk. And if one wants to check if an approach is really secure, one should forget about technical acronyms and protocols and start thinking about "real world situations": would you hide your keys somewhere where everybody hides his keys ? would you accept to tell a central person where you plan to go ? would you trust a "friend" who has to tell secrets on demand ? would you accept to know nothing about your children acquaintances just because of their privacy ? would you accept that somebody opens your mail letters just to check if it is an unwanted message ? Would you hand over your pictures to somebody knowing that once you do it this person can sell the picture without having to as you ? Probably not, nevertheless people massively accept it...

So is it "the doomsday clock for tls-host=" ? Probably yes, but with all this "privacy saving tools, protocols, means, etc" it's also the doomsday clock for privacy, regardless of what we are told.

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