test/scripts/1990-TCP-Fast-Open/1990

   1 # TCP Fast Open
   2 #
   3 # Linux:
   4 # Both server and client-side TFO support must be enabled in the
   5 # kernel, 'sudo sh -c "echo 3 > /proc/sys/net/ipv4/tcp_fastopen"'.
   6 #
   7 # A packet capture on the loopback interface will show the TFO
   8 # option on the SYN, but the fast-output SMTP banner will not
   9 # be seen unless you also deliberately emulate a long path:
  10 # 'sudo tc qdisc add dev lo root netem delay 100ms'
  11 #
  12 # First time runs will see a TFO request option only; subsequent
  13 # ones should see the TFO cookie and fast-output SMTP banner
  14 # (currently on a separate packet after the server SYN,ACK but before
  15 # the client ACK).
  16 #
  17 # The client log => lint.ex  should have a "TFO" element.
  18 # Assuming this is the first run since boot, the a@test recipient will not.
  19 #
  20 # The server log <= line for b@test.ex  should have a "TFO" element, but
  21 # this will only be obtained when the above delay is inserted into the
  22 # loopback net path.
  23 #
  24 #
  25 #
  26 # FreeBSD: it looks like you have to compile a custom kernel, with
  27 # 'options TCP_RFC7413' in the config.  Also set
  28 # 'net.inet.tcp.fastopen.enabled=1' in /etc/sysctl.conf
  29 # Untested.
  30 #
  31 exim -DSERVER=server -bd -oX PORT_D
  32 ****
  33 #
  34 exim a@test.ex
  35 Testing
  36 ****
  37 sleep 3
  38 #
  39 exim b@test.ex
  40 Testing
  41 ****
  42 sleep 3
  43 #
  44 killdaemon
  45 no_msglog_check