Re: Terrapin

Brian Pence <[email protected]> writes:=0A=0A>OpenSSH supports a=
 number of transport-layer hardening measures under a=0A>"strict KEX" featu=
re. This feature is signalled similarly to the RFC8308 ext-=0A>info feature=
: by including a additional algorithm in the initial=0A>SSH2_MSG_KEXINIT ke=
x_algorithms field.=0A=0AUgh, another incompletely-specified [*] homebrew a=
dd-on kludged onto SSH=0Awithout any public consultation, to fix the proble=
ms caused by the first=0Aincompletely-specified homebrew add-on kludged ont=
o SSH without any public=0Aconsultation.  What happened to publishing RFCs =
and getting public review and=0Afeedback in case there are problems?=0A=0A>=
During initial KEX, terminate the connection if any unexpected or out-of-=
=0A>sequence packet is received. This includes terminating the connection i=
f the=0A>first packet received is not SSH2_MSG_KEXINIT. Unexpected packets =
for the=0A>purpose of strict KEX include messages that are otherwise valid =
at any time=0A>during the connection such as SSH2_MSG_DEBUG and SSH2_MSG_IG=
NORE.=0A=0AAre there any implementations that would break if you did this a=
nyway?=0AAssuming that what it's trying to say is "terminate the connection=
 if the=0Afirst packet isn't SSH2_MSG_KEXINIT".=0A=0APeter.=0A=0A[*] See th=
e second paragraph quoted above with ambiguous and vague terms like=0A    "=
unexpected", "includes ...", etc.