FYI HEAD now refuses <1024 bit DH keys in group-exchange

Ángel González keisial at
Sat Oct 17 08:58:33 AEDT 2015

On 16/10/15 21:07, Damien Miller wrote:
> Hi,
> I just committed a change to HEAD that raises the minimum Diffie-Hellman
> group size that the client will accept from 1024 to 2048 bits.
> Connections to well-behaved servers should not be affected by this
> change, but I've identified at least one case where a misconfigured
> server can cause connection failure. The errors look like:
>> ssh_dispatch_run_fatal: Connection to DH GEX group out of
>> range
> The problematic software is OpenSSH<3.9 or Sun_SSH (all versions).
> It will use a fixed 1024 bit DH group as an implicit fallback if
> /etc/ssh/moduli is missing, unreadable or empty.

Thanks for the heads-up.
We know that people will find that a bit cryptic. What about showing a 
message like:
"A Diffie-Hellman group of %d bits is too weak. Does the server have a 
/etc/ssh/moduli file with suitable values?"

Best regards

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