Don't send anything in response to a SSH_MSG_CHANNEL_REQUEST if we have already sent a SSH_MSG_CHANNEL_CLOSE. This fixes a bug triggered by more recent versions of putty with tcp fowarding and window adjustment request messages.

open(IN,"<crypt.ind");
open(OUT,">crypt.ind.tmp");
$a = <IN>;
print OUT  "$a\n\\addcontentsline{toc}{chapter}{Index}\n";
while (<IN>) {
   print OUT $_;
}
close OUT;
close IN;
system("mv -f crypt.ind.tmp crypt.ind");