Can we disable diffie-hellman-group-exchange-sha1 by default?

[Yegor Ievlev]

I disable everything except curve25519 on my servers and clients (if
they only need to connect to my servers).

On Fri, Feb 15, 2019 at 7:59 AM Yegor Ievlev <koops1997 at gmail.com> wrote:
>
> I don't think there is any point to generate so many moduli. Actually,
> 3 moduli of sizes 2048, 3072 and 4096 seem like a sane choice.
>
> On Fri, Feb 15, 2019 at 7:58 AM Darren Tucker <dtucker at dtucker.net> wrote:
> >
> > On Fri, 15 Feb 2019 at 14:22, Yegor Ievlev <koops1997 at gmail.com> wrote:
> > > I'm not nearly knowledgeable enough in crypto to fully understand your
> > > answer, but I will try. I wonder why moduli are not automatically
> > > generated the first time sshd is started though. That would make much
> > > more sense than shipping a default moduli file but also asking
> > > everyone to replace it with their own.
> >
> > 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.
> >
> > With those caveats, you are also welcome to add the appropriate
> > ssh-keygen commands to your startup scripts.
> >
> > --
> > Darren Tucker (dtucker at dtucker.net)
> > GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860  37F4 9357 ECEF 11EA A6FA (new)
> >     Good judgement comes with experience. Unfortunately, the experience
> > usually comes from bad judgement.