Most of them are now _mandatory_ P3 scripts, because I'm tired of
maintaining everything to be compatible with both versions.
The current exceptions are gdb.py (which has to live with whatever gdb
gives it), and kh2reg.py (which is actually designed for other people
to use, and some of them might still be stuck on P2 for the moment).
It now expects its standard input to be connected to the same PuTTY
its standard output is talking to, i.e. expects to be invoked as a
proxy command. It conducts the same sample key exchange as it used to,
but now reads the SSH greeting and first couple of packets back from
PuTTY and minimally checks that they're something like what it was
expecting.
(In the process, I've also fixed a mistake in the Python message code
enumeration, which caused one of those expect() calls to fail.)
encodelib.py is a Python library which implements some handy SSH-2
encoding primitives; samplekex.py uses that to fabricate the start of
an SSH connection, up to the point where key exchange totally fails
its crypto.
The idea is that you adapt samplekex.py to construct initial-kex
sequences with particular properties, in order to test robustness and
security fixes that affect the initial-kex sequence. For example, I
used an adaptation of this to test the Diffie-Hellman range check
that's just gone into 0.64.
