Prova a utilizzare il ssh sequenza di escape della terminazione della connessione.
Nel ssh sessione, inserisci ~. (punto tilde). Non vedrai i caratteri quando li digiti, ma la sessione terminerà immediatamente.
$ ~.
$ Connection to me.myhost.com closed.
Da man 1 ssh
The supported escapes (assuming the default ‘~’) are:
~. Disconnect.
~^Z Background ssh.
~# List forwarded connections.
~& Background ssh at logout when waiting for forwarded
connection / X11 sessions to terminate.
~? Display a list of escape characters.
~B Send a BREAK to the remote system (only useful for SSH protocol
version 2 and if the peer supports it).
~C Open command line. Currently this allows the addition of port
forwardings using the -L, -R and -D options (see above). It also
allows the cancellation of existing remote port-forwardings using
-KR[bind_address:]port. !command allows the user to execute a
local command if the PermitLocalCommand option is enabled in
ssh_config(5). Basic help is available, using the -h option.
~R Request rekeying of the connection (only useful for SSH protocol
version 2 and if the peer supports it).
Basta premere Ctrl D e ti disconnetterà lì per tenere premuto ctrl e premere "d" finché la finestra non scompare.
Chiudi semplicemente PuTTY. (Alt +F4 per impostazione predefinita IIRC.)