To sum this up, we should add the deprecation warning as suggested by Erik.
But we should at the same time have the UI for NCP available so that people don’t have to touch their configuration more than once.
-Michael
On 12 Oct 2023, at 10:36, Adolf Belka adolf.belka@ipfire.org wrote:
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:Migratea...
I had seen that overall page before but obviously not read the details well enough of that specific entry. The entry makes it clear that from openvpn-2.7 onwards the 64 bit ciphers will no longer be accepted even as data-fallback ones.
that´s 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 so will miss the message about the 64 bit BF-CBC etc being removed from 2.7 onwards.
So having the 64 bit ciphers in the data-fallback table but not allowing them to be used and instead giving a warning message about the cipher being removed in the future is a way to make the changes more visible 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 the openvpn changes that will come with the IPFire updates being worked on and the future ones with openvpn-2.7
This patch can be found in here --> https://git.ipfire.org/?p=people/ummeegge/ipfire-2.x.git;a=commit;h=dd11f427...
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. >
-- Sent from my laptop