PuTTY semi-bug ssh2-kex-repeat

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summary: Ability to initiate SSH-2 key re-exchange
class: semi-bug: This might or might not be a bug, depending on your precise definition of what a bug is.
difficulty: tricky: Needs many tuits.
depends: ssh2-kex-data
priority: medium: This should be fixed one day.
fixed-in: 2004-11-28 812870d1b304d8f22633614f59c6690c05fcc029 (0.58)

Either side of an SSH-2 connection may initiate a key re-exchange. Not all servers bother to do this, although I suspect most are happy to accept a re-exchange initiated by the client.

PuTTY currently never initiates a re-exchange; it relies on the server to do so, and responds to it when it does. This doesn't always happen - at least some versions of the OpenSSH server follow the same policy, which means a re-exchange never occurs. We really ought to initiate re-exchange ourselves if the server doesn't.

Before this can be done, we need to fix ssh2-kex-data, since otherwise the chances of receiving a data packet from the server just after sending our KEXINIT would be unacceptably high.

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Audit trail for this semi-bug.
(last revision of this bug record was at 2017-04-28 16:52:45 +0100)