From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adolf Belka To: development@lists.ipfire.org Subject: Re: Status update on openvpn work Date: Thu, 12 Oct 2023 11:36:05 +0200 Message-ID: <34e7b27b-d0a8-4e0a-ba81-b12bf54a507f@ipfire.org> In-Reply-To: <3af89cd55d28e489b235d6035e5620ec8868485e.camel@ipfire.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3381340097887026275==" List-Id: --===============3381340097887026275== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi Erik, On 12/10/2023 08:06, ummeegge wrote: > Am Donnerstag, dem 12.10.2023 um 07:56 +0200 schrieb ummeegge: >>> OpenVPN plan to remove those weak ciphers completely in version 2.7 >>> If a user at that time still had a client with say BF-CBC would the >>> negotiation still work then or would it fail because OpenVPN no >>> longer >>> recognises the old weak cipher? >> This is true according to the OpenVPN 'Deprecated Option' wiki --> >> https://community.openvpn.net/openvpn/wiki/DeprecatedOptions#Policy:Migrat= eawayfromdeprecatedciphers.Status:Inprogress I had seen that overall page before but obviously not read the details=20 well enough of that specific entry. The entry makes it clear that from=20 openvpn-2.7 onwards the 64 bit ciphers will no longer be accepted even=20 as data-fallback ones. >> that=C2=B4s causes, beneath the OpenSSL-3.x decision, to leave the >> deprecated ciphers out of the Roadwarrior list (N2N is another thing >> since it do no understands cipher negotiation) but pushed at that >> time >> an idea to bring on some warnings for the users before the IPFire >> decision to leave the broken ciphers out of any list since the server >> can not see what client configuration is in place. > To correct this statement, mostly users do not see/recognize such > warnings in the OpenVPN logs, the server does see it! I see what you are saying. The users tend not to look at their logs and=20 so will miss the message about the 64 bit BF-CBC etc being removed from=20 2.7 onwards. So having the 64 bit ciphers in the data-fallback table but not allowing=20 them to be used and instead giving a warning message about the cipher=20 being removed in the future is a way to make the changes more visible=20 that the user needs to do and the potential timing scenario. I think I will also need to put together a supporting info blog post on=20 the openvpn changes that will come with the IPFire updates being worked=20 on and the future ones with openvpn-2.7 >> This patch can be found in here --> >> https://git.ipfire.org/?p=3Dpeople/ummeegge/ipfire-2.x.git;a=3Dcommit;h=3D= dd11f42776f1b60660f4e862d6e847e746b9411b Thanks for the clarification. Regards, Adolf. >>> Regards, >>> >>> Adolf. >> Best, >> >> Erik >> >>>>> Then pressed Start OpenVPN Server and nothing happened. Checked >>>>> the >>>>> logs and there is the openssl error >>>>> >>>>> OpenSSL: error:0308010C:digital envelope routines::unsupported >>>>> >>>>> which occurs because Openssl-3.x doesn't support the older >>>>> ciphers >>>>> like BF unless legacy is selected. In this case I think it is >>>>> the >>>>> OpenVPN server conf file that requires the >>>>> >>>>> providers legacy default >>>>> >>>>> to be included, rather than the client conf file. >>>>> >>>>> Still it does feel like two steps forward and one backwards so >>>>> overall still making progress. >>>>> >>>>> >>>>> Regards, >>>>> >>>>> Adolf. >>>> Best, >>>> >>>> Erik >>>>> On 09/10/2023 14:05, Adolf Belka wrote: >>>>>> Hi All, >>>>>> >>>>>> >>>>>> Over the last week I have been working on the openvpn update >>>>>> using >>>>>> Erik's previous patches as my starting point. >>>>>> >>>>>> My first attempt to try and be able to understand the changes >>>>>> from >>>>>> each patch to figure out what I needed to do proved difficult >>>>>> for >>>>>> me to work with. >>>>>> >>>>>> What I then did was take the current ovpnmain.cgi and apply >>>>>> all >>>>>> of >>>>>> Erik's patches to it. >>>>>> >>>>>> Then I have gone through that new version of ovpnmain.cgi and >>>>>> made >>>>>> the changes based on previous discussions with Michael. >>>>>> >>>>>> So I have removed the b2sum options that were present for the >>>>>> Data >>>>>> and Channel Authentication. >>>>>> >>>>>> I also moved all the cryptographic options from an additional >>>>>> advanced cryptographic options button into the Advanced >>>>>> Server >>>>>> options button. >>>>>> >>>>>> I was successful in doing all the above and then tested the >>>>>> ovpnmain.cgi out with a vm using the existing openvpn-2.5.9 >>>>>> version >>>>>> for openvpn. >>>>>> >>>>>> My old profile for my laptop which had a ciphers entry worked >>>>>> without any problem. My laptop was working withy openvpn- >>>>>> 2.6.6 >>>>>> >>>>>> I then created a new profile using the new ovpnmain.cgi using >>>>>> the >>>>>> negotiation option which ended up with a data-ciphers line. >>>>>> That >>>>>> also worked in making a successful openvpn tunnel with my >>>>>> laptop >>>>>> without any issues. >>>>>> >>>>>> I then downgraded my laptop to openvpn-2.4.8 and had to >>>>>> install >>>>>> openvpn-1.1.1 to make that work. >>>>>> >>>>>> With that client version on my laptop both the old and new >>>>>> profiles >>>>>> connected with a tunnel with no problems. >>>>>> >>>>>> I then tried downgrading my laptop to openvpn-2.3.14 but to >>>>>> make >>>>>> this work I would have had to downgrade the laptop to >>>>>> openssl- >>>>>> 1.0.0 >>>>>> which I was not willing to do as that is very old and very >>>>>> insecure. >>>>>> >>>>>> The oldest openvpn version working with openssl-1.1.1 is >>>>>> 2.4.0 >>>>>> which is nearly 7 years old. >>>>>> >>>>>> That version also worked with both the old and new laptop >>>>>> profiles. >>>>>> >>>>>> I then tested out the openvpn server on my IPFire vm with a >>>>>> 2.6.0 >>>>>> and 2.6.6 version of openvpn. >>>>>> >>>>>> Both these openvpn versions worked with both the old and new >>>>>> laptop >>>>>> connection profiles with my laptop on version 2.4.0 and on >>>>>> 2.6.6 >>>>>> >>>>>> All the above was using network manager with its openvpn >>>>>> plugin >>>>>> option on the laptop for making the openvpn tunnel >>>>>> connections. >>>>>> >>>>>> As far as I can tell everything is working fine when >>>>>> negotiation is >>>>>> specified on the server. Old profiles that just use the >>>>>> cipher >>>>>> option also work fine. Therefore my plan is to only use the >>>>>> negotiation option and not make it selectable for older >>>>>> clients. >>>>>> The data-ciphers-fallback option in the server seems to be >>>>>> doing >>>>>> its job. >>>>>> >>>>>> The negotiation option on the server was able to connect to a >>>>>> 2.4.0 >>>>>> client on my laptop. >>>>>> >>>>>> According to the OpenVPN wiki on cipher negotiation the data- >>>>>> ciphers-fallback option will work with 2.4.x and 2.3.x >>>>>> clients. >>>>>> As >>>>>> the 2.3.x clients need to be using openssl-1.0.0 then I think >>>>>> if >>>>>> those clients work then fine but nothing further back. >>>>>> >>>>>> Overall, I am very happy with what I have succeeded in doing >>>>>> so >>>>>> far. I achieved things much quicker than I had expected. >>>>>> >>>>>> I will now try and see about creating a profile on a CU 179 >>>>>> based >>>>>> system that uses one of the old insecure ciphers such as Blow >>>>>> Fish >>>>>> and restore that into my evaluation vm and see how that works >>>>>> with >>>>>> my laptop when I have it downgraded to openvpn-2.4.0 >>>>>> >>>>>> I already know that if the laptop is at openvpn-2.6.6 then it >>>>>> will >>>>>> not accept a blowfish cipher (or another weak cipher such as >>>>>> DES) >>>>>> as that is something I tested in the past. >>>>>> >>>>>> If that also works then my plan will be to take the updated >>>>>> ovpnmain.cgi and split the changes into a new range of >>>>>> patches >>>>>> and >>>>>> then submit them for consideration. >>>>>> >>>>>> That will probably end up later in November as I will be busy >>>>>> with >>>>>> personal things at the end of October / beginning of >>>>>> November. >>>>>> >>>>>> >>>>>> Regards, >>>>>> >>>>>> Adolf. >>>>>> --=20 Sent from my laptop --===============3381340097887026275==--