X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Ralf Zenklusen r.zenklusen@barinformatik.ch" Received: from mail.barinformatik.ch ([81.201.202.2] verified) by list.communigate.ru (CommuniGate Pro SMTP 6.3.11) with ESMTPS id 60511933 for CGatePro@list.communigate.ru; Wed, 27 Apr 2022 09:25:46 +0300 Received-SPF: pass receiver=mail.communigate.ru; client-ip=81.201.202.2; envelope-from=r.zenklusen@barinformatik.ch X-ExtScanner: Niversoft's Find_Attachments Received: from [81.201.203.54] (account ralf.zenklusen@barinformatik.ch) by barinformatik.ch (CommuniGate Pro IMAP 6.2.12) with XMIT id 397977750 for CGatePro@list.communigate.ru; Wed, 27 Apr 2022 08:25:32 +0200 Subject: AW: [CGP] Qualys "This server does not support Forward Secrecy with the reference browsers. Grade capped to B." problem - Case[AA7Q0427-953ID] Date: Wed, 27 Apr 2022 08:25:31 +0200 Message-Id: <840cb1a759068f45aff6c57f2f66344d@barinformatik.ch> In-Reply-To: MIME-Version: 1.0 Thread-Topic: [CGP] Qualys "This server does not support Forward Secrecy with the reference browsers. Grade capped to B." problem - Case[AA7Q0427-953ID] Priority: Normal Importance: normal X-MSMail-Priority: normal X-Priority: 3 Sensitivity: Normal Thread-Index: AdhZ/5iKVyqfFANbSRq4ieYoUZYu0A== To: "CommuniGate Pro Russian Discussions" X-Mailer: CommuniGate Pro MAPI Connector 1.52.54.18/1.54.12.35 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi, it would be nice to separate web (http) and mail (smtp) SSL/TLS settings in= CGatePro. Usually you want http to have very strict/strong settings. Users should use= the latest browsers and tests will be happy. But smtp needs more relaxed settings to work with all the legacy mail serve= rs that are still around. Kind regards Ralf Zenklusen -----Urspr=C3=BCngliche Nachricht----- Von: CommuniGate Pro Russian Discussions Gesendet: Mittwoch, 27. April 2022 08:10 An: CommuniGate Pro Russian Discussions Betreff: Re: [CGP] Qualys "This server does not support Forward Secrecy wit= h the reference browsers. Grade capped to B." problem - Case[AA7Q0427-953ID= ] Hello, On 2022-04-27 06:18, S=C3=A9rgio Ara=C3=BAjo sergio@3gnt.net wrote: > Greetings, > > Why does a freshly installed CentOS 7.9 / CommuniGate Pro 6.3.11 > server only gets a B grade with the Qualys SSL checker > (see attached screenshot) ? The way they assign grades after their tests is questionable. For example t= o test for some vulnerabilities they would simply check the alert code reci= eved on connection termination witth a break-in attempt: if it's not the one they expect they would consider the implementation vuln= erable, without more checks, regardless the fact that unsafe connection was= terminated. If they see the older or weaker algorithms supported, they wou= ld cap your grade - even when those weaker algorithms are safer with oledr = TLS versions and client would normally select the strongest suite presented= by the server. As for this particular "forward secrecy" - this should be a= bout ECDH(E) suits and the DH key size. CGPro supports ECDH (long-term DH p= air) but not the Ephemeral ECDH (when DH pair is re-generated for every exc= hange in a TLS session), as that would require much more CPU for the multip= le connections the server should be able to endure. The default DH key size= is also considered too short by these tests: 6.3 uses 1536 by default, whi= ch is cobsidered effective against all but state-level attacks, but can be = increased by a command-line parameter. We plan to support TLS 1.3 and EC certificates in future versions. Not sure= if ECDHE is that important for what most use as a mail server. [] > > The server uses a valid SSL certificate, and if use an Apache server > as a reverse proxy, I get an A grade, which makes me think it's > something with the CommuniGate Pro SSL implementation. However, I feel > using Apache as a reverse proxy makes no sense, since CommuniGate Pro > has an embedded Web server. Well, when you need a web server, you use a web server. CGPro may be enough= to serve its interfaces and home pages, but for a high load web site I wou= ld use apache or nginx anyway. > How do i fix/workaround the "/This server does not support Forward > Secrecy with the reference browsers. Grade capped to B./" problem > reported by the Qualys SSL checker > ? The short answer is "you can't do that now". Well, generally hunting for a higher grade without understanding their mean= ing is not a good idea. The "forward secrecy" thing (ECDH) is the protectio= n against decoding your traffic collected at full in the past with the cert= ificate private key compromised in future. Every session is encrypted by a = key unique for that session and it's _very_ hard to derive that key even if= the certificate was compromised. But it's still possible for agencys with = lots of CPU power to brute force for finding the actual session key and dec= ode that session traffic. The "perfect forward secrecy" (ECDHE) reduces the= prize for that brute force attack: not the entire session but only some shorter exchange can be decoded. So, even with "imperfect forward secrecy" your traffic is well protected. I= s protecting mail server traffic from an attack that is possible mostly in = theory really worth of investing much more CPU power? > Regards, > -- > *S=C3=A9rgio Ara=C3=BAjo* > S=C3=B3cio-gerente | Director T=C3=A9cnico [] -- Best regards, Dmitry Akindinov ################################################################## =D0=92=D1=8B =D0=BF=D0=BE=D0=BB=D1=83=D1=87=D0=B8=D0=BB=D0=B8 =D1=8D=D1=82= =D0=BE =D1=81=D0=BE=D0=BE=D0=B1=D1=89=D0=B5=D0=BD=D0=B8=D0=B5 =D0=BF=D0=BE= =D1=82=D0=BE=D0=BC=D1=83, =D1=87=D1=82=D0=BE =D0=BF=D0=BE=D0=B4=D0=BF=D0=B8= =D1=81=D0=B0=D0=BD=D1=8B =D0=BD=D0=B0 =D1=81=D0=BF=D0=B8=D1=81=D0=BE=D0=BA = =D1=80=D0=B0=D1=81=D1=81=D1=8B=D0=BB=D0=BA=D0=B8 . =D0=A7=D1=82=D0=BE=D0=B1=D1=8B =D0=BE=D1=82=D0=BF=D0=B8=D1=81=D0=B0=D1=82= =D1=8C=D1=81=D1=8F, =D0=BE=D1=82=D0=BF=D1=80=D0=B0=D0=B2=D1=8C=D1=82=D0=B5 = =D1=81=D0=BE=D0=BE=D0=B1=D1=89=D0=B5=D0=BD=D0=B8=D0=B5 =D0=BD=D0=B0 =D0=B0= =D0=B4=D1=80=D0=B5=D1=81 =D0=A7=D1=82=D0=BE=D0=B1=D1=8B =D0=BF=D0=B5=D1=80=D0=B5=D0=BA=D0=BB=D1=8E= =D1=87=D0=B8=D1=82=D1=8C=D1=81=D1=8F =D0=B2 =D1=80=D0=B5=D0=B6=D0=B8=D0=BC = =D0=B4=D0=B0=D0=B9=D0=B4=D0=B6=D0=B5=D1=81=D1=82=D0=B0 - mailto: =D0=A7=D1=82=D0=BE=D0=B1=D1=8B =D0=BF=D0=B5=D1=80=D0=B5=D0=BA=D0=BB=D1=8E= =D1=87=D0=B8=D1=82=D1=8C=D1=81=D1=8F =D0=B2 =D0=B8=D0=BD=D0=B4=D0=B5=D0=BA= =D1=81=D0=BD=D1=8B=D0=B9 =D1=80=D0=B5=D0=B6=D0=B8=D0=BC - mailto: =D0=94=D0=BB=D1=8F =D0=B0=D0=B4=D0=BC=D0=B8=D0=BD=D0=B8=D1=81=D1=82=D1=80= =D0=B0=D1=82=D0=B8=D0=B2=D0=BD=D1=8B=D1=85 =D0=B7=D0=B0=D0=BF=D1=80=D0=BE= =D1=81=D0=BE=D0=B2 =D0=B0=D0=B4=D1=80=D0=B5=D1=81 =D0=90=D1=80=D1=85=D0=B8=D0=B2 =D1=81=D0=BF=D0=B8=D1=81=D0=BA=D0=B0: http:/= /list.communigate.ru/Lists/CGatePro/List.html