Or simply disable non-EC DH, like I do for all my servers. On Sat, Feb 16, 2019 at 10:57 AM Jochen Bern <Jochen.Bern@xxxxxxxxx> wrote: > > On 02/15/2019 06:07 PM, Christoph Anton Mitterer wrote: > > On Fri, 2019-02-15 at 15:57 +1100, Darren Tucker wrote: > >> That was the original intent (and it's mentioned in RFC4419) however > >> each moduli file we ship (70-80 instances of 6 sizes) takes about 1 > >> cpu-month to generate on a lowish-power x86-64 machine. Most of it > >> is parallelizable, but even then it'd likely take a few hours to > >> generate one of each size. I imagine that'd cause some complaints > >> about startup time. > > > > One way of handling this, at least if the moduli generation was nicely > > interruptable, is that distros ship a file, e.g. /etc/ssh/moduli.dist > > but by some mean (init script, systemd unit, maybe even sshd itself) a > > daemon that does calculation of new moduli values is started whenever > > /etc/ssh/moduli (no ".dist") isn't found. > > I'm (manually) creating the shorter moduli anew for every VM I set up > (which may have but one core), but have the longer ones copied after > being created *once* for every "platform" (definition subject to > practicality). Running *that* much of ssh-keygen already takes longer > than people are willing to wait for the VM that's needed oh-so-urgently > for a customer-visible change. I can't say that I would be very happy > about an out-of-the-box "Hulk smash puny CPU!!" behavior. > > Considering that the moduli file already varies with the distro, I'ld > say that the duty of recognizing it / that situation (and reacting to > it) is *not* on the OpenSSH maintainers, beyond maybe suggesting a > global mechanism to do so (*). Since /etc/ssh/moduli's syntax supports > comment lines, how about having the distro moduli files include one alike > > # DO-MODULI-WARNING This is an unchanged $DISTRO moduli file. You *want* > to (create and) install one of your own (or delete this comment to hide > your disgrace and make this OpenSSH shut up). > > and then have the distro's choice of escalating warnings / > countermeasures (**) triggered by a '^# DO-MODULI-WARNING' regexp? > > (*) I first wanted to suggest recognizing distro's default moduli files > by checksum, but that would discourage having it updated / recomputed > frequently by the package maintainers (boatload of historic checksums to > check for), which is *not* what we want. > > (**) Say, start with the equivalent of a hardcoded login banner, > escalate all the way up to running a *very* niced-down moduli generation > when nobody intervened for a year ... > > Regards, > -- > Jochen Bern > Systemingenieur > > www.binect.de > www.facebook.de/binect > > _______________________________________________ > openssh-unix-dev mailing list > openssh-unix-dev@xxxxxxxxxxx > https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
