# A packet capture on the loopback interface will show the TFO
# 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'
+# 'sudo tc qdisc add dev lo root netem delay 50ms'
+# You'll need iproute-tc installed, for the tc command.
+# 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'
+#
+# MacOS:
+# The kernel seems to have TFO enabled both ways as default.
+# There is a net.inet.tcp.clear_tfocache parameter
+## sysctl -w foo-val
+#
+# For network delays there is something called 'Network Link Conditioner'
+# which might do the job. But how to manipulate it?
+#
+#
+sudo perl
+system ("tc qdisc add dev lo root netem delay 50ms");
+****
#
# First time runs will see a TFO request option only; subsequent
# ones should see the TFO cookie and fast-output SMTP banner
# (currently on a separate packet after the server SYN,ACK but before
# the client ACK).
#
-# The log <= line should have a "TFO" element.
+# The client log => line should have a "TFO" element.
+# The server log <= line for a@test.ex should not.
+#
+# First clear any previously-obtained cookie:
+sudo perl
+system ("ip tcp_metrics delete 127.0.0.1");
+****
#
-# If the client-side is disabled in the kernel, Exim logs
-# will become noisy.
#
#
# FreeBSD: it looks like you have to compile a custom kernel, with
#
exim -DSERVER=server -bd -oX PORT_D
****
+#
exim a@test.ex
Testing
****
sleep 3
+#
+# The server log <= line for b@test.ex should have a "TFO" element, but
+# this will only be obtained when the above delay is inserted into the
+# loopback net path.
+#
exim b@test.ex
Testing
****
sleep 3
+#
+#
+sudo perl
+system ("tc qdisc delete dev lo root");
+****
+#
killdaemon
no_msglog_check
git://git.exim.org / exim.git / blobdiff