1$6 ~ /^ack/ && $5 !~ /[SFR]/ 	{
2	# given a tcpdump ftp trace, output one line for each ack
3	# in the form
4	#   <ack time> <seq no>
5	# where <ack time> is the time packet was acked (in seconds with
6	# zero at time of first packet) and <seq no> is the tcp sequence
7	# number of the ack divided by 1024 (i.e., Kbytes acked).
8	#
9	# convert time to seconds
10	n = split ($1,t,":")
11	tim = t[1]*3600 + t[2]*60 + t[3]
12	if (! tzero) {
13		tzero = tim
14		OFS = "\t"
15	}
16	# get packet sequence number
17	printf "%7.2f\t%g\n", tim-tzero, $7/1024
18	}
19