To test tcp-md5 do:

* compile and install kernel with TCP_SIGNATURE support

* add this to /etc/ipsec.conf (the md5 'secret' is just a sample)
	add 127.0.0.1 127.0.0.1 tcp 0x1000 -A tcp-md5 "0e3a9ac42ceca8260f1d6fbc46a9707c";

* enable it in /etc/rc.conf with
	ipsec_enable="YES"
  and apply it with sh /etc/rc.d/ipsec start

 [ off course you can also manually add it using setkey(8) ]

* compile tcpconnect in here running:
    make

* start tcpdump (secret as above, port is just a sample):
    tcpdump -l -n -i lo0 -s 0 -M "0e3a9ac42ceca8260f1d6fbc46a9707c" tcp and port 2345

* run the server (use same port as given to tcpdump):
    ./tcpconnect server 2345

* run the client (use same port as given to tcpdump):
    ./tcpconnect client 127.0.0.1 2345 1 tcpmd5

* check tcpdump output

# end