# option on the SYN, but the fast-output SMTP banner will not
# be seen unless you also deliberately emulate a long path:
# 'sudo tc qdisc add dev lo root netem delay 100ms'
+# You'll need kernel-modules-extra installed, or you get
+# an unhelpful error from RTNETLINK.
+# To tidy up: 'sudo tc qdisc delete dev lo root'
#
# First time runs will see a TFO request option only; subsequent
# ones should see the TFO cookie and fast-output SMTP banner
# this will only be obtained when the above delay is inserted into the
# loopback net path.
#
+# this attempt to tidy up does not work
+#sudo perl
+#open (my $fh, "/proc/sys/net/ipv4/tcp_fastopen_key");
+#print $fh "00000000-00000000-00000000-00000000";
+#close $fh;
+#****
#
#
# FreeBSD: it looks like you have to compile a custom kernel, with