I see.
Yes, using explicitly disabled algorithms is a very surprising behavior.
- Tim.
On 9/23/17, 10:32 AM, "Joseph S Testa II" <jtesta@xxxxxxxxxxxxxxxxxxxx> wrote:
On 09/22/2017 06:55 PM, Tim Broberg wrote:
> Do I understand correctly, that you find the security of group 14 unacceptable and yet you left it enabled?
In the end, I'm trying to ensure a minimum equivalent of 128-bits of
security. Group14 is 2048-bits, which roughly translates to 112-bits. [1]
To this end, I disabled the "diffie-hellman-group14-sha1" and
"diffie-hellman-group14-sha256" kex algorithms, but the problem is that
the group exchange "diffie-hellman-group-exchange-sha256" is not
respecting the admin's wishes, and falls back to group14, even when
specifically told not to (by the admin removing 2048-bit groups in
/etc/ssh/moduli).
There's currently no way to ensure 100% that 2048-bit DH is disabled.
- Joe
[1] See NIST Special Publication 800-57, Part 1, Revision 4, p. 53,
<https://urldefense.proofpoint.com/v2/url?u=http-3A__nvlpubs.nist.gov_nistpubs_SpecialPublications_NIST.SP.800-2D57pt1r4.pdf&d=DwICaQ&c=Zok6nrOF6Fe0JtVEqKh3FEeUbToa1PtNBZf6G01cvEQ&r=WxtmI2HcpDF2j1UPw-tBSatMtcAHcEc-gP6FGr3XijQ&m=fr1RUDYTTiem9YAE7u99sskaxPHiNB54oK08WY93mS8&s=GY-4snvYRtttrYTbXRzbrHkN-gQ9t-xJIaXAodVLK8M&e=>.
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