Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
On 24/07/2020 12:45, Arne Schwabe wrote: > First of all I did not want to reply to this since we had a lengthy > discussion on IRC. > >> Lets take a few steps back try to see a broader picture. >> >> * --ncp-ciphers was introduced in OpenVPN 2.4 as a brand new option. >> >> * Steffan has suggested to add --data-ciphers alias into the next v2.4 >> release; to which I agree(!). > > Yes, this sounds like a simple idea but also has the danger of creating > more confusion. > > I feel it better to have ncp-cipher and data-ciphers coexist. Then you > also have the understand that ncp-cipher is an older/less capable > version of data-ciphers. > > OpenVPN 2.4 has a number of oddities in NCP support: > > - the client always announces AES-GCM support even if disabled in > ncp-ciphers > - the server will always push the first cipher of its ncp-ciphers list > to the client. These oddities, they sounds like bugs, or? If I try to put on my Never-used-NCP-before-hat, this would not be what I would expect. Why haven't we resolved this within the current 2.4 scope without changing options? > From a user perspective data-ciphers is a true superset of ncp-ciphers. > All existing ncp-ciphers setup will continue to work on 2.5 but the > data-ciphers option from 2.5 is likely to break on 2.5 if you don't take > into account the 2.4 oddities. > >> * I propose we add a warning whenever --ncp-ciphers used, recommending the >> user to switch to --data-ciphers as soon as possible. > > As compromise maybe something like > > NOTE: Rewriting old-option x y z to new new-option x y z As mentioned on IRC, yes. I am willing to accept msg(M_INFO, "Rewriting deprecated option X to the replacement Y" ... [...] >> * 12 months *after* the v2.6 release is out, we can remove --ncp-ciphers. >> But >> since we will not do option changes mid-release easily, it might be natural >> to remove this in OpenVPN 2.7 at earliest. >> >> This means --ncp-ciphers will be supported in 2.4 for the life time of that >> release. And v2.4 is supported for *at least* 18 months after v2.5 is >> released. It also guarantees --ncp-ciphers will first be removed when we >> release OpenVPN 2.7. >> >> What would be a problem with such a schedule? Because I don't understand the >> real objection you have to remove options which ends up duplicating other >> options. > > > My general problem is that I don't see a real advantage in removing > ncp-cipher but see a lot of downsides removing it. I hear about you seeing downsides ... but I have not seen any argument here convincing me otherwise. This overall process should take care of supporting all reasonable OpenVPN 2.x versions. >> At the same time ... it is also important for me that we try to see this at >> from an even bigger perspective than just --ncp-ciphers/--data-ciphers or >> even >> --udp-mtu alone. Now I'm shifting the discussion to a more generic product >> life cycle perspective. >> >> If we skimp through this and just allow whatever option duplications we head >> into, just because we're too concerned about various breakages with old >> configurations or setups - it will not be the last time we might end up in >> such discussions UNLESS we can find a proper and reasonable process for >> deprecation (which we in fact already defined for feature deprecation 10 >> years >> ago! [1]). >> >> If we cannot remove options during the whole life time of OpenVPN, we cannot >> touch compression options or possibly even deprecate any compression at all - >> because we need to support both compression and decompression for the whole >> lifetime of OpenVPN. This also extends into how to ensure proper OpenVPN 3 >> compatibility as well. > > The amount of time we spend on testing/developing etc on compression and > the complexity it introduces is vastly different from ncp-cipher That is true. But at the same time, if we do not have a proper deprecation process where we draw the line in which OpenVPN versions we are willing to support (from a functional perspective), we cannot touch compression. Which is why I'm trying to raise the points of a bigger picture. We need to find a reasonable solution to which OpenVPN versions we are willing to support, and when those versions enters the unsupported side we should be free to cleanup code and options related to the behavior and functionality only these now not supported releases provided. >> And if we cannot remove any options during the eternal life time of OpenVPN, >> I >> will see no other alternative to being even more critical and rejective to >> add >> new options. We already have pretty close to 300 options in OpenVPN. That >> is >> an insane amount - where a typical common OpenVPN setup might need up to 20 >> of >> these options, the rest are for all kinds of special cases. And we have >> several competing solutions which are far simpler in many aspects which new >> users might just as well prefer. >> >> Even though I
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
First of all I did not want to reply to this since we had a lengthy discussion on IRC. > Lets take a few steps back try to see a broader picture. > > * --ncp-ciphers was introduced in OpenVPN 2.4 as a brand new option. > > * Steffan has suggested to add --data-ciphers alias into the next v2.4 > release; to which I agree(!). Yes, this sounds like a simple idea but also has the danger of creating more confusion. I feel it better to have ncp-cipher and data-ciphers coexist. Then you also have the understand that ncp-cipher is an older/less capable version of data-ciphers. OpenVPN 2.4 has a number of oddities in NCP support: - the client always announces AES-GCM support even if disabled in ncp-ciphers - the server will always push the first cipher of its ncp-ciphers list to the client. From a user perspective data-ciphers is a true superset of ncp-ciphers. All existing ncp-ciphers setup will continue to work on 2.5 but the data-ciphers option from 2.5 is likely to break on 2.5 if you don't take into account the 2.4 oddities. > * I propose we add a warning whenever --ncp-ciphers used, recommending the > user to switch to --data-ciphers as soon as possible. As compromise maybe something like NOTE: Rewriting old-option x y z to new new-option x y z > > * We keep both --ncp-ciphers *and* --data-ciphers in v2.5 and v2.6. > > * When v2.5 is released v2.4 goes into "old stable support" - where both > alternatives will work. v2.4 is guaranteed to be supported by the community > for at least 6 months with full support [0] after v2.5 is released. > > * When 2.6 is released, v2.4 goes into "git tree only" support but will have a > > 12 month "old stable support" guarantee [0]. > > * 12 months *after* the v2.6 release is out, we can remove --ncp-ciphers. But > since we will not do option changes mid-release easily, it might be natural > to remove this in OpenVPN 2.7 at earliest. > > This means --ncp-ciphers will be supported in 2.4 for the life time of that > release. And v2.4 is supported for *at least* 18 months after v2.5 is > released. It also guarantees --ncp-ciphers will first be removed when we > release OpenVPN 2.7. > > What would be a problem with such a schedule? Because I don't understand the > real objection you have to remove options which ends up duplicating other > options. My general problem is that I don't see a real advantage in removing ncp-cipher but see a lot of downsides removing it. > > At the same time ... it is also important for me that we try to see this at > from an even bigger perspective than just --ncp-ciphers/--data-ciphers or even > --udp-mtu alone. Now I'm shifting the discussion to a more generic product > life cycle perspective. > > If we skimp through this and just allow whatever option duplications we head > into, just because we're too concerned about various breakages with old > configurations or setups - it will not be the last time we might end up in > such discussions UNLESS we can find a proper and reasonable process for > deprecation (which we in fact already defined for feature deprecation 10 years > ago! [1]). > > If we cannot remove options during the whole life time of OpenVPN, we cannot > touch compression options or possibly even deprecate any compression at all - > because we need to support both compression and decompression for the whole > lifetime of OpenVPN. This also extends into how to ensure proper OpenVPN 3 > compatibility as well. The amount of time we spend on testing/developing etc on compression and the complexity it introduces is vastly different from ncp-cipher > And if we cannot remove any options during the eternal life time of OpenVPN, I > will see no other alternative to being even more critical and rejective to add > new options. We already have pretty close to 300 options in OpenVPN. That is > an insane amount - where a typical common OpenVPN setup might need up to 20 of > these options, the rest are for all kinds of special cases. And we have > several competing solutions which are far simpler in many aspects which new > users might just as well prefer. > > Even though I highlight the number of options we have, I do NOT say that we > should swipe them all out and reduce the amount to 50 or so; for some users > they have a _real_ value and provides really useful features. But I want us > to save the options which do have a REAL value, not because unsupported > OpenVPN versions might break or "10 bytes extra source code" is too heavy to > carry around for an alias option. I'm arguing for keeping options covering > _REAL_ USE CASE for users. And no, breaking unsupported OpenVPN releases is > NOT a real use case from my point of view. This is the point where we disagree. I still think that we should weigh the pros and cons if we still want have compatibility. And also to consider if there are alternatives/workaround for the setups/users affected. > But back to the deprecated options ... If we
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
On 24/07/2020 10:14, Steffan Karger wrote: > Hi, > > On 17-07-2020 15:47, Arne Schwabe wrote: >> The change in name signals that data-ciphers is the preferred way to >> configure data channel (and not --cipher). The data prefix is chosen >> to avoid ambiguity and make it distinct from tls-cipher for the TLS >> ciphers. >> >> Signed-off-by: Arne Schwabe >> --- >> Changes.rst| 13 ++--- >> doc/man-sections/protocol-options.rst | 11 +++ >> doc/man-sections/server-options.rst| 4 ++-- >> sample/sample-config-files/client.conf | 2 +- >> src/openvpn/multi.c| 4 ++-- >> src/openvpn/options.c | 5 +++-- >> src/openvpn/ssl_ncp.c | 4 ++-- >> 7 files changed, 27 insertions(+), 16 deletions(-) >> >> diff --git a/Changes.rst b/Changes.rst >> index 6e283270..2158c8e7 100644 >> --- a/Changes.rst >> +++ b/Changes.rst >> @@ -14,12 +14,19 @@ ChaCha20-Poly1305 cipher support >> channel. >> >> Improved Data channel cipher negotiation >> +The option ``ncp-ciphers`` has been renamed to ``data-ciphers``. >> +The old name is still accepted. The change in name signals that >> +``data-ciphers`` is the preferred way to configure data channel >> +ciphers and the data prefix is chosen to avoid the ambiguity that >> +exists with ``--cipher`` for the data cipher and ``tls-cipher`` >> +for the TLS ciphers. >> + >> OpenVPN clients will now signal all supported ciphers from the >> -``ncp-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN >> -servers will select the first common cipher from the ``ncp-ciphers`` >> +``data-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN >> +servers will select the first common cipher from the ``data-ciphers`` >> list instead of blindly pushing the first cipher of the list. This >> allows to use a configuration like >> -``ncp-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that >> +``data-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that >> prefers ChaCha20-Poly1305 but uses it only if the client supports it. >> >> Asynchronous (deferred) authentication support for auth-pam plugin. >> diff --git a/doc/man-sections/protocol-options.rst >> b/doc/man-sections/protocol-options.rst >> index 923d2da0..051f1d32 100644 >> --- a/doc/man-sections/protocol-options.rst >> +++ b/doc/man-sections/protocol-options.rst >> @@ -62,7 +62,7 @@ configured in a compatible way between both the local and >> remote side. >>The default is :code:`BF-CBC`, an abbreviation for Blowfish in Cipher >>Block Chaining mode. When cipher negotiation (NCP) is allowed, >>OpenVPN 2.4 and newer on both client and server side will automatically >> - upgrade to :code:`AES-256-GCM`. See ``--ncp-ciphers`` and >> + upgrade to :code:`AES-256-GCM`. See ``--data-ciphers`` and >>``--ncp-disable`` for more details on NCP. >> >>Using :code:`BF-CBC` is no longer recommended, because of its 64-bit >> @@ -169,7 +169,7 @@ configured in a compatible way between both the local >> and remote side. >>non-standard key lengths, and a larger key may offer no real guarantee >>of greater security, or may even reduce security. >> >> ---ncp-ciphers cipher-list >> +--data-ciphers cipher-list >>Restrict the allowed ciphers to be negotiated to the ciphers in >>``cipher-list``. ``cipher-list`` is a colon-separated list of ciphers, >>and defaults to :code:`AES-256-GCM:AES-128-GCM`. >> @@ -189,9 +189,9 @@ configured in a compatible way between both the local >> and remote side. >>Additionally, to allow for more smooth transition, if NCP is enabled, >>OpenVPN will inherit the cipher of the peer if that cipher is different >>from the local ``--cipher`` setting, but the peer cipher is one of the >> - ciphers specified in ``--ncp-ciphers``. E.g. a non-NCP client (<=v2.3, >> + ciphers specified in ``--data-ciphers``. E.g. a non-NCP client (<=v2.3, >>or with --ncp-disabled set) connecting to a NCP server (v2.4+) with >> - ``--cipher BF-CBC`` and ``--ncp-ciphers AES-256-GCM:AES-256-CBC`` set can >> + ``--cipher BF-CBC`` and ``--data-ciphers AES-256-GCM:AES-256-CBC`` set can >>either specify ``--cipher BF-CBC`` or ``--cipher AES-256-CBC`` and both >>will work. >> >> @@ -201,6 +201,9 @@ configured in a compatible way between both the local >> and remote side. >>This list is restricted to be 127 chars long after conversion to OpenVPN >>ciphers. >> >> + This option was called ``ncp-ciphers`` in OpenVPN 2.4 but has been renamed >> + to ``data-ciphers`` in OpenVPN 2.5 to more accurately reflect its meaning. >> + >> --ncp-disable >>Disable "Negotiable Crypto Parameters". This completely disables cipher >>negotiation. >> diff --git a/doc/man-sections/server-options.rst >> b/doc/man-sections/server-options.rst >> index c24aec0b..74ad5e18 100644 >> ---
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
Hi, On 17-07-2020 15:47, Arne Schwabe wrote: > The change in name signals that data-ciphers is the preferred way to > configure data channel (and not --cipher). The data prefix is chosen > to avoid ambiguity and make it distinct from tls-cipher for the TLS > ciphers. > > Signed-off-by: Arne Schwabe > --- > Changes.rst| 13 ++--- > doc/man-sections/protocol-options.rst | 11 +++ > doc/man-sections/server-options.rst| 4 ++-- > sample/sample-config-files/client.conf | 2 +- > src/openvpn/multi.c| 4 ++-- > src/openvpn/options.c | 5 +++-- > src/openvpn/ssl_ncp.c | 4 ++-- > 7 files changed, 27 insertions(+), 16 deletions(-) > > diff --git a/Changes.rst b/Changes.rst > index 6e283270..2158c8e7 100644 > --- a/Changes.rst > +++ b/Changes.rst > @@ -14,12 +14,19 @@ ChaCha20-Poly1305 cipher support > channel. > > Improved Data channel cipher negotiation > +The option ``ncp-ciphers`` has been renamed to ``data-ciphers``. > +The old name is still accepted. The change in name signals that > +``data-ciphers`` is the preferred way to configure data channel > +ciphers and the data prefix is chosen to avoid the ambiguity that > +exists with ``--cipher`` for the data cipher and ``tls-cipher`` > +for the TLS ciphers. > + > OpenVPN clients will now signal all supported ciphers from the > -``ncp-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN > -servers will select the first common cipher from the ``ncp-ciphers`` > +``data-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN > +servers will select the first common cipher from the ``data-ciphers`` > list instead of blindly pushing the first cipher of the list. This > allows to use a configuration like > -``ncp-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that > +``data-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that > prefers ChaCha20-Poly1305 but uses it only if the client supports it. > > Asynchronous (deferred) authentication support for auth-pam plugin. > diff --git a/doc/man-sections/protocol-options.rst > b/doc/man-sections/protocol-options.rst > index 923d2da0..051f1d32 100644 > --- a/doc/man-sections/protocol-options.rst > +++ b/doc/man-sections/protocol-options.rst > @@ -62,7 +62,7 @@ configured in a compatible way between both the local and > remote side. >The default is :code:`BF-CBC`, an abbreviation for Blowfish in Cipher >Block Chaining mode. When cipher negotiation (NCP) is allowed, >OpenVPN 2.4 and newer on both client and server side will automatically > - upgrade to :code:`AES-256-GCM`. See ``--ncp-ciphers`` and > + upgrade to :code:`AES-256-GCM`. See ``--data-ciphers`` and >``--ncp-disable`` for more details on NCP. > >Using :code:`BF-CBC` is no longer recommended, because of its 64-bit > @@ -169,7 +169,7 @@ configured in a compatible way between both the local and > remote side. >non-standard key lengths, and a larger key may offer no real guarantee >of greater security, or may even reduce security. > > ---ncp-ciphers cipher-list > +--data-ciphers cipher-list >Restrict the allowed ciphers to be negotiated to the ciphers in >``cipher-list``. ``cipher-list`` is a colon-separated list of ciphers, >and defaults to :code:`AES-256-GCM:AES-128-GCM`. > @@ -189,9 +189,9 @@ configured in a compatible way between both the local and > remote side. >Additionally, to allow for more smooth transition, if NCP is enabled, >OpenVPN will inherit the cipher of the peer if that cipher is different >from the local ``--cipher`` setting, but the peer cipher is one of the > - ciphers specified in ``--ncp-ciphers``. E.g. a non-NCP client (<=v2.3, > + ciphers specified in ``--data-ciphers``. E.g. a non-NCP client (<=v2.3, >or with --ncp-disabled set) connecting to a NCP server (v2.4+) with > - ``--cipher BF-CBC`` and ``--ncp-ciphers AES-256-GCM:AES-256-CBC`` set can > + ``--cipher BF-CBC`` and ``--data-ciphers AES-256-GCM:AES-256-CBC`` set can >either specify ``--cipher BF-CBC`` or ``--cipher AES-256-CBC`` and both >will work. > > @@ -201,6 +201,9 @@ configured in a compatible way between both the local and > remote side. >This list is restricted to be 127 chars long after conversion to OpenVPN >ciphers. > > + This option was called ``ncp-ciphers`` in OpenVPN 2.4 but has been renamed > + to ``data-ciphers`` in OpenVPN 2.5 to more accurately reflect its meaning. > + > --ncp-disable >Disable "Negotiable Crypto Parameters". This completely disables cipher >negotiation. > diff --git a/doc/man-sections/server-options.rst > b/doc/man-sections/server-options.rst > index c24aec0b..74ad5e18 100644 > --- a/doc/man-sections/server-options.rst > +++ b/doc/man-sections/server-options.rst > @@ -473,8 +473,8 @@ fast hardware. SSL/TLS authentication must be used in >
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
Hi, On 23-07-2020 18:09, David Sommerseth wrote: >> This was a deliberate decision. We really want to people to move towards >> ncp and putting another hurdle with having an option that works better >> on but gives a warning and a option that does not work on 2.4 does not >> help here. If we decide that really aliases are a no-go in OpenVPN then >> I would rather drop data-ciphers and stay with ncp-ciphers forever for >> this reason. > > Lets take a few steps back try to see a broader picture. > > [..snip..] > > We really need a proper and sane processes to allow the development of OpenVPN > to have a chance to move on and leave things behind when appropriate, to be > able to evolve and grow with the future - without being strangled by what > existed in the far past (meaning: no longer community supported releases). > Otherwise I do fear for the future of OpenVPN 2.x. > > By having a clear strategy and adhering to a process of feature/option > management in OpenVPN, we give clearly defined time-window for stability and > functionality for our users. This predictability is, in my experience, much > more important to users than if a specifically named option is supported or > not. Yes, you've made these points clear earlier on IRC. I (and with me Arne and Gert) just don't agree with you on some of the details, resulting in a different verdict on this patch. None of us has trouble with deprecating options. We appreciate the work you've put into the DeprecatedOptions page, and all of us have sent and/or acked patched to remove dangerous or obsolete options. This difference is in how we weigh the pros and cons per option. So I'll leave the broader picture for now, and summarize why I'm going to ACK Arne's patch exactly because is *doesn't* print a warning when the old name is used. Option name aliases add negligible code complexity and are trivial to maintain. (Just look at --udp-mtu.) Keeping them in allows users to write configs that work well and do not produce any warnings on both older and newer versions. (Printing warnings for harmless things reduces the value of the other warnings we print.) Let's focus our time and effort on reducing actual complexity. -Steffan ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
On 23/07/2020 13:36, Arne Schwabe wrote: > >>> +++ b/src/openvpn/options.c >>> @@ -536,7 +536,7 @@ static const char usage_message[] = >>> "--cipher alg: Encrypt packets with cipher algorithm alg\n" >>> " (default=%s).\n" >>> " Set alg=none to disable encryption.\n" >>> -"--ncp-ciphers list : List of ciphers that are allowed to be >>> negotiated.\n" >>> +"--data-ciphers list : List of ciphers that are allowed to be >>> negotiated.\n" >>> "--ncp-disable : (DEPRECATED) Disable cipher negotiation.\n" >>> "--prng alg [nsl] : For PRNG, use digest algorithm alg, and\n" >>> " nonce_secret_len=nsl. Set alg=none to disable >>> PRNG.\n" >>> @@ -7866,7 +7866,8 @@ add_option(struct options *options, >>> VERIFY_PERMISSION(OPT_P_NCP|OPT_P_INSTANCE); >>> options->ciphername = p[1]; >>> } >>> -else if (streq(p[0], "ncp-ciphers") && p[1] && !p[2]) >>> +else if ((streq(p[0], "data-ciphers") || streq(p[0], "ncp-ciphers")) >>> +&& p[1] && !p[2]) >> >> I do agree to using --data-ciphers instead of --ncp-ciphers, that is far more >> user-friendly naming of this feature. NCP is a more technical >> "under-the-hood" terminology which users don't really need to relate to, >> where >> --data-ciphers better explains what it is used for. >> >> But I do reject NOT adding a deprecation path for --ncp-ciphers. We should >> support --ncp-ciphers for 1-2 major releases, but after that it should be >> removed. We have too many options and we certainly should avoid duplicating >> options with the exact same functionality. Just let me clarify the "1-2 major releases" was too hasty and not well thought numbers. Please read my reasoning below for what I really intended to say. > This was a deliberate decision. We really want to people to move towards > ncp and putting another hurdle with having an option that works better > on but gives a warning and a option that does not work on 2.4 does not > help here. If we decide that really aliases are a no-go in OpenVPN then > I would rather drop data-ciphers and stay with ncp-ciphers forever for > this reason. Lets take a few steps back try to see a broader picture. * --ncp-ciphers was introduced in OpenVPN 2.4 as a brand new option. * Steffan has suggested to add --data-ciphers alias into the next v2.4 release; to which I agree(!). * I propose we add a warning whenever --ncp-ciphers used, recommending the user to switch to --data-ciphers as soon as possible. * We keep both --ncp-ciphers *and* --data-ciphers in v2.5 and v2.6. * When v2.5 is released v2.4 goes into "old stable support" - where both alternatives will work. v2.4 is guaranteed to be supported by the community for at least 6 months with full support [0] after v2.5 is released. * When 2.6 is released, v2.4 goes into "git tree only" support but will have a 12 month "old stable support" guarantee [0]. * 12 months *after* the v2.6 release is out, we can remove --ncp-ciphers. But since we will not do option changes mid-release easily, it might be natural to remove this in OpenVPN 2.7 at earliest. This means --ncp-ciphers will be supported in 2.4 for the life time of that release. And v2.4 is supported for *at least* 18 months after v2.5 is released. It also guarantees --ncp-ciphers will first be removed when we release OpenVPN 2.7. What would be a problem with such a schedule? Because I don't understand the real objection you have to remove options which ends up duplicating other options. At the same time ... it is also important for me that we try to see this at from an even bigger perspective than just --ncp-ciphers/--data-ciphers or even --udp-mtu alone. Now I'm shifting the discussion to a more generic product life cycle perspective. If we skimp through this and just allow whatever option duplications we head into, just because we're too concerned about various breakages with old configurations or setups - it will not be the last time we might end up in such discussions UNLESS we can find a proper and reasonable process for deprecation (which we in fact already defined for feature deprecation 10 years ago! [1]). If we cannot remove options during the whole life time of OpenVPN, we cannot touch compression options or possibly even deprecate any compression at all - because we need to support both compression and decompression for the whole lifetime of OpenVPN. This also extends into how to ensure proper OpenVPN 3 compatibility as well. And if we cannot remove any options during the eternal life time of OpenVPN, I will see no other alternative to being even more critical and rejective to add new options. We already have pretty close to 300 options in OpenVPN. That is an insane amount - where a typical common OpenVPN setup might need up to 20 of these options, the rest are for all kinds of special cases. And we have several competing solutions which
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
>> +++ b/src/openvpn/options.c >> @@ -536,7 +536,7 @@ static const char usage_message[] = >> "--cipher alg: Encrypt packets with cipher algorithm alg\n" >> " (default=%s).\n" >> " Set alg=none to disable encryption.\n" >> -"--ncp-ciphers list : List of ciphers that are allowed to be >> negotiated.\n" >> +"--data-ciphers list : List of ciphers that are allowed to be >> negotiated.\n" >> "--ncp-disable : (DEPRECATED) Disable cipher negotiation.\n" >> "--prng alg [nsl] : For PRNG, use digest algorithm alg, and\n" >> " nonce_secret_len=nsl. Set alg=none to disable >> PRNG.\n" >> @@ -7866,7 +7866,8 @@ add_option(struct options *options, >> VERIFY_PERMISSION(OPT_P_NCP|OPT_P_INSTANCE); >> options->ciphername = p[1]; >> } >> -else if (streq(p[0], "ncp-ciphers") && p[1] && !p[2]) >> +else if ((streq(p[0], "data-ciphers") || streq(p[0], "ncp-ciphers")) >> +&& p[1] && !p[2]) > > I do agree to using --data-ciphers instead of --ncp-ciphers, that is far more > user-friendly naming of this feature. NCP is a more technical > "under-the-hood" terminology which users don't really need to relate to, where > --data-ciphers better explains what it is used for. > > But I do reject NOT adding a deprecation path for --ncp-ciphers. We should > support --ncp-ciphers for 1-2 major releases, but after that it should be > removed. We have too many options and we certainly should avoid duplicating > options with the exact same functionality. This was a deliberate decision. We really want to people to move towards ncp and putting another hurdle with having an option that works better on but gives a warning and a option that does not work on 2.4 does not help here. If we decide that really aliases are a no-go in OpenVPN then I would rather drop data-ciphers and stay with ncp-ciphers forever for this reason. Arne signature.asc Description: OpenPGP digital signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
On 17/07/2020 15:47, Arne Schwabe wrote: > The change in name signals that data-ciphers is the preferred way to > configure data channel (and not --cipher). The data prefix is chosen > to avoid ambiguity and make it distinct from tls-cipher for the TLS > ciphers. > > Signed-off-by: Arne Schwabe > --- > Changes.rst| 13 ++--- > doc/man-sections/protocol-options.rst | 11 +++ > doc/man-sections/server-options.rst| 4 ++-- > sample/sample-config-files/client.conf | 2 +- > src/openvpn/multi.c| 4 ++-- > src/openvpn/options.c | 5 +++-- > src/openvpn/ssl_ncp.c | 4 ++-- > 7 files changed, 27 insertions(+), 16 deletions(-) > [...snip...] > diff --git a/src/openvpn/options.c b/src/openvpn/options.c > index 31e33ae3..896abcde 100644 > --- a/src/openvpn/options.c > +++ b/src/openvpn/options.c > @@ -536,7 +536,7 @@ static const char usage_message[] = > "--cipher alg: Encrypt packets with cipher algorithm alg\n" > " (default=%s).\n" > " Set alg=none to disable encryption.\n" > -"--ncp-ciphers list : List of ciphers that are allowed to be > negotiated.\n" > +"--data-ciphers list : List of ciphers that are allowed to be > negotiated.\n" > "--ncp-disable : (DEPRECATED) Disable cipher negotiation.\n" > "--prng alg [nsl] : For PRNG, use digest algorithm alg, and\n" > " nonce_secret_len=nsl. Set alg=none to disable > PRNG.\n" > @@ -7866,7 +7866,8 @@ add_option(struct options *options, > VERIFY_PERMISSION(OPT_P_NCP|OPT_P_INSTANCE); > options->ciphername = p[1]; > } > -else if (streq(p[0], "ncp-ciphers") && p[1] && !p[2]) > +else if ((streq(p[0], "data-ciphers") || streq(p[0], "ncp-ciphers")) > +&& p[1] && !p[2]) I do agree to using --data-ciphers instead of --ncp-ciphers, that is far more user-friendly naming of this feature. NCP is a more technical "under-the-hood" terminology which users don't really need to relate to, where --data-ciphers better explains what it is used for. But I do reject NOT adding a deprecation path for --ncp-ciphers. We should support --ncp-ciphers for 1-2 major releases, but after that it should be removed. We have too many options and we certainly should avoid duplicating options with the exact same functionality. -- kind regards, David Sommerseth OpenVPN Inc signature.asc Description: OpenPGP digital signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
[Openvpn-devel] [PATCH 8/9] Rename ncp-ciphers to data-ciphers
The change in name signals that data-ciphers is the preferred way to configure data channel (and not --cipher). The data prefix is chosen to avoid ambiguity and make it distinct from tls-cipher for the TLS ciphers. Signed-off-by: Arne Schwabe --- Changes.rst| 13 ++--- doc/man-sections/protocol-options.rst | 11 +++ doc/man-sections/server-options.rst| 4 ++-- sample/sample-config-files/client.conf | 2 +- src/openvpn/multi.c| 4 ++-- src/openvpn/options.c | 5 +++-- src/openvpn/ssl_ncp.c | 4 ++-- 7 files changed, 27 insertions(+), 16 deletions(-) diff --git a/Changes.rst b/Changes.rst index 6e283270..2158c8e7 100644 --- a/Changes.rst +++ b/Changes.rst @@ -14,12 +14,19 @@ ChaCha20-Poly1305 cipher support channel. Improved Data channel cipher negotiation +The option ``ncp-ciphers`` has been renamed to ``data-ciphers``. +The old name is still accepted. The change in name signals that +``data-ciphers`` is the preferred way to configure data channel +ciphers and the data prefix is chosen to avoid the ambiguity that +exists with ``--cipher`` for the data cipher and ``tls-cipher`` +for the TLS ciphers. + OpenVPN clients will now signal all supported ciphers from the -``ncp-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN -servers will select the first common cipher from the ``ncp-ciphers`` +``data-ciphers`` option to the server via ``IV_CIPHERS``. OpenVPN +servers will select the first common cipher from the ``data-ciphers`` list instead of blindly pushing the first cipher of the list. This allows to use a configuration like -``ncp-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that +``data-ciphers ChaCha20-Poly1305:AES-256-GCM`` on the server that prefers ChaCha20-Poly1305 but uses it only if the client supports it. Asynchronous (deferred) authentication support for auth-pam plugin. diff --git a/doc/man-sections/protocol-options.rst b/doc/man-sections/protocol-options.rst index 923d2da0..051f1d32 100644 --- a/doc/man-sections/protocol-options.rst +++ b/doc/man-sections/protocol-options.rst @@ -62,7 +62,7 @@ configured in a compatible way between both the local and remote side. The default is :code:`BF-CBC`, an abbreviation for Blowfish in Cipher Block Chaining mode. When cipher negotiation (NCP) is allowed, OpenVPN 2.4 and newer on both client and server side will automatically - upgrade to :code:`AES-256-GCM`. See ``--ncp-ciphers`` and + upgrade to :code:`AES-256-GCM`. See ``--data-ciphers`` and ``--ncp-disable`` for more details on NCP. Using :code:`BF-CBC` is no longer recommended, because of its 64-bit @@ -169,7 +169,7 @@ configured in a compatible way between both the local and remote side. non-standard key lengths, and a larger key may offer no real guarantee of greater security, or may even reduce security. ---ncp-ciphers cipher-list +--data-ciphers cipher-list Restrict the allowed ciphers to be negotiated to the ciphers in ``cipher-list``. ``cipher-list`` is a colon-separated list of ciphers, and defaults to :code:`AES-256-GCM:AES-128-GCM`. @@ -189,9 +189,9 @@ configured in a compatible way between both the local and remote side. Additionally, to allow for more smooth transition, if NCP is enabled, OpenVPN will inherit the cipher of the peer if that cipher is different from the local ``--cipher`` setting, but the peer cipher is one of the - ciphers specified in ``--ncp-ciphers``. E.g. a non-NCP client (<=v2.3, + ciphers specified in ``--data-ciphers``. E.g. a non-NCP client (<=v2.3, or with --ncp-disabled set) connecting to a NCP server (v2.4+) with - ``--cipher BF-CBC`` and ``--ncp-ciphers AES-256-GCM:AES-256-CBC`` set can + ``--cipher BF-CBC`` and ``--data-ciphers AES-256-GCM:AES-256-CBC`` set can either specify ``--cipher BF-CBC`` or ``--cipher AES-256-CBC`` and both will work. @@ -201,6 +201,9 @@ configured in a compatible way between both the local and remote side. This list is restricted to be 127 chars long after conversion to OpenVPN ciphers. + This option was called ``ncp-ciphers`` in OpenVPN 2.4 but has been renamed + to ``data-ciphers`` in OpenVPN 2.5 to more accurately reflect its meaning. + --ncp-disable Disable "Negotiable Crypto Parameters". This completely disables cipher negotiation. diff --git a/doc/man-sections/server-options.rst b/doc/man-sections/server-options.rst index c24aec0b..74ad5e18 100644 --- a/doc/man-sections/server-options.rst +++ b/doc/man-sections/server-options.rst @@ -473,8 +473,8 @@ fast hardware. SSL/TLS authentication must be used in this mode. *AES-GCM-128* and *AES-GCM-256*. :code:`IV_CIPHERS=` -The client pushes the list of configured ciphers with the -``--ciphers`` option to the server. +The client announces the list of supported
