+#
+# Disable the TFO blackhole detection, as we seem to be running foul of it.
+# If bitten, we see the expected EINPROGRESS for sendto, yet no TFO cookie
+# option on the SYN.
+#
+sudo perl
+system ("[ -e /proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_sec ] && echo 0 > /proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_sec");
+****
+#