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the TCPdump network dissector

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Win32/Include Fix error, pick up stuff from libpcap bittypes.h.
lbl Add "os-osf4.h" to declare "snprintf()" on Digital UNIX 4.x.
missing Get rid of unnecessary configure script tests and missing/XXX.h headers.
tests print-dhcp6.c: Fix bugs in DH6OPT_IA_NA, DH6OPT_IA_PD, DH6OPT_IA_TA, …
win32 add support for the RPKI/Router Protocol as per draft-ietf-sidr-rpki-…
.cvsignore tcpdump.1 is generated from tcpdump.1.in.
.gitattributes Added options to gitattributes
.gitignore .gitignore: add failure-outputs.txt
.travis.yml .travis.yml: Do 2 Travis CI builds; one with building our own libpcap
CHANGES Add changes only in the trunk.
CREDITS add DNSSL (RFC6106) support
INSTALL.txt From Bert Vermeulen: add a USB printer, and fix the error message
LICENSE added license file
Makefile-devel-adds backout 1.2
Makefile.in "lmp.new" isn't a checked-in file; don't make it part of the distribu…
PLATFORMS updated platforms
README We're using Git, not CVS, now.
Readme.Win32 Added a readme that explains how to compile tcpdump under Win32.
TODO We already added DLT_LINUX_COOKED, except it's called DLT_LINUX_SLL, and
VERSION PRE-GIT, not PRE_GIT.
acconfig.h Get rid of unnecessary configure script tests and missing/XXX.h headers.
aclocal.m4 Ask for the libpcap Makefile while we're at it.
addrtoname.c Sanity Checking added to addrtoname
addrtoname.h Back out DLT_PFSYNC support.
af.c af.h/c: make several structs const
af.h af.h/c: make several structs const
ah.h The "__attribute__((packed))" tag on structures causes some files not to
aodv.h The now-expired draft-perkins-aodv6-01 specified a different order for
appletalk.h add EIGRP support for Appletalk, display cosmetics to better indicate…
arcnet.h
atime.awk Initial revision
atm.h rework the oam printer: add support for payload printing of OAM loopb…
atmuni31.h Precede the VCI values with VCI_, to avoid collisions (such as with
bgp.h rework bgp, ldp, lsp-ping to use the common l2vpn_encaps tokenlist
bootp.h Prevent GCC from doing some alignment-unsafe optimizations on SPARC.
bpf_dump.c Fix signature of bpf_dump() to match that of libpcap's version.
chdlc.h Add support for NetBSD DLT_PPP_SERIAL (PPP in HDLC-like framing, as per
checksum.c Get rid of unnecessary assignment.
config.guess Update config.guess and config.sub to the latest versions.
config.h.in Handle systems with getrpcbynumber() but no header file for it.
config.sub Update config.guess and config.sub to the latest versions.
configure Simplify the detection of OpenSSL libcrypto by using standard autoconf
configure.in Simplify the detection of OpenSSL libcrypto by using standard autoconf
cpack.c Support RX flags, MCS and the vendor namespace, and fix Rate.
cpack.h Support RX flags, MCS and the vendor namespace, and fix Rate.
dccp.h from Gerrit Renker <gerrit@erg.abdn.ac.uk>:
decnet.h The "__attribute__((packed))" tag on structures causes some files not to
decode_prefix.h Add some attribute/TLV length checks.
enc.h Add support for OpenBSD DLT_ENC.
esp.h The "__attribute__((packed))" tag on structures causes some files not to
ether.h The "__attribute__((packed))" tag on structures causes some files not to
ethertype.h TIPC support.
extract.h -add support (TLV parser) for the juniper .pcap extensions
fddi.h The "__attribute__((packed))" tag on structures causes some files not to
forces.h fixes from Jamal Hadi Salim <hadi@mojatatu.com> for forces: SPARSE da…
gmpls.c gmpls.h/c: mark several structs as const
gmpls.h gmpls.h/c: mark several structs as const
gmt2local.c Have the configure script arrange that the Makefile define _U_
gmt2local.h Initial revision
icmp6.h add DNSSL (RFC6106) support
ieee802_11.h When parsing IEs in a management frame, save the *first* IE of a given
ieee802_11_radio.h Support RX flags, MCS and the vendor namespace, and fix Rate.
igrp.h The "__attribute__((packed))" tag on structures causes some files not to
in_cksum.c
install-sh Initial revision
interface.h Add "radius" as an option for -T.
ip.h Add a routine to do the "checksum with pseudo-header" stuff for IPv4.
ip6.h Use nextproto6_cksum() for XXX-over-IPv6 checksums.
ipfc.h The "__attribute__((packed))" tag on structures causes some files not to
ipnet.h The patches attached to this email are required to get a fully workin…
ipproto.c Add a CARP dissector and a command-line option to dissect proto 112 a…
ipproto.h Add a CARP dissector and a command-line option to dissect proto 112 a…
ipsec_doi.h The "__attribute__((packed))" tag on structures causes some files not to
ipx.h The "__attribute__((packed))" tag on structures causes some files not to
isakmp.h added "make check"
l2tp.h L2TP dissector changes, from Motonori Shindo:
l2vpn.c l2vpn.h/c: mark several structs as const
l2vpn.h l2vpn.h/c: mark several structs as const
lane.h
llc.h From From Carles Kishimoto <carles.kishimoto@gmail.com>:
machdep.c _U_ is defined by the Makefile; we shouldn't redefine it ourselves.
machdep.h s/sprintf/snprintf/.
makemib Update makemib and print-snmp.c license, via OpenBSD: jakob got
mib.h patches to help build on Linux 2.2
mkdep Initial revision
mpls.h make MPLS label handling macros available to the outside world
nameser.h The topmost bit in the class field isn't a "cache flush" flag in mDNS
netbios.h The "__attribute__((packed))" tag on structures causes some files not to
netdissect.h Add "radius" as an option for -T.
nfs.h Enhance NFS access request messages.
nfsfh.h Get rid of casts of pointers-to-const to pointers-to-nonconst.
nlpid.c Added support for SPB
nlpid.h Added support for SPB
ntp.h provide decent multipline output for the NTP printer
oakley.h The "__attribute__((packed))" tag on structures causes some files not to
ospf.h Constify some arguments.
ospf6.h -rework the OSPFv3 printer:
oui.c Add error checking and support for DCB Exchange protocol (DCBX) versi…
oui.h Add error checking and support for DCB Exchange protocol (DCBX) versi…
packetdat.awk Initial revision
parsenfsfh.c From NetBSD:
pcap-missing.h Use pcap_dump_ftell() rather than casting a pcap_dumper_t * to a FILE *
pcap_dump_ftell.c Use pcap_dump_ftell() rather than casting a pcap_dumper_t * to a FILE *
pmap_prot.h Get rid of the multiple-include protection in our RPC headers, so we
ppi.h From: Darren Reed <darren.reed@oracle.com>
ppp.h - add a brief ML-PPP printer
print-802_11.c Update Action codes for handle_action function according to 11s amend…
print-802_15_4.c Handle the reserved value for the addressing modes.
print-ah.c Have various routines for printing non-final headers for IPv4/IPv6
print-aodv.c Add bounds checking.
print-ap1394.c reworked print-ether to use netdissect
print-arcnet.c Convert the IPv6 printer to use netdissect.
print-arp.c Put in missing break.
print-ascii.c Have "ascii_print()" do the "-A" output, and nothing but the "-A"
print-atalk.c Add additional length checking, print unsigned lengths with %u.
print-atm.c Remove unnecessary test.
print-babel.c update for current Babel auth spec
print-beep.c Have the configure script arrange that the Makefile define _U_
print-bfd.c Based on a patch from Marc Binderberger, fix the handling of non-control
print-bgp.c
print-bootp.c removing unnecessary processing for zero length options
print-bt.c Don't directly fetch multi-byte integers from packets.
print-carp.c Add a CARP dissector and a command-line option to dissect proto 112 a…
print-cdp.c Fix plurals in packet count messages.
print-cfm.c Initialize the appropriate member of the msg_ptr union in all case arms
print-chdlc.c Convert the IPv6 printer to use netdissect.
print-cip.c Add a flag to suppress the "default_print()" call made in various
print-cnfp.c Get rid of an unused variable.
print-dccp.c Add a routine to do the "checksum with pseudo-header" stuff for IPv4.
print-decnet.c Add a bunch of bounds checks.
print-dhcp6.c print-dhcp6.c: update of the references RFC with their titles
print-domain.c add DNSSL (RFC6106) support
print-dtp.c From From Carles Kishimoto <carles.kishimoto@gmail.com>:
print-dvmrp.c Add missing bounds checking to the DVMRP and PIM print routines.
print-eap.c from Carles Kishimoto <carles.kishimoto@gmail.com>: make the EAP prin…
print-egp.c print EGP header in new-world-order style
print-eigrp.c Fix a bunch of "sizeof(sizeof(XXX))".
print-enc.c
print-esp.c Don't directly fetch multi-byte integers from packets.
print-ether.c TIPC support.
print-fddi.c Have print_llc() clear out the extracted_ethertype argument, rather than
print-forces.c Check the return value of some print routines.
print-fr.c Convert the IPv6 printer to use netdissect.
print-frag6.c Get rid of an unused variable.
print-gre.c Convert the IPv6 printer to use netdissect.
print-hsrp.c Add an "fn_printzp()" routine for printing null-padded strings (strings
print-icmp.c Go with Wireshark's Internet checksum routine.
print-icmp6.c fix printing of infinite lifetime in ICMPv6
print-igmp.c Previous commit accidentally used 6 seconds cutoff.
print-igrp.c Get rid of an unused variable.
print-ip.c do not convert protocol to names if -n flag
print-ip6.c Use nextproto6_cksum() for XXX-over-IPv6 checksums.
print-ip6opts.c Print a space after the options if there are any options.
print-ipcomp.c Have various routines for printing non-final headers for IPv4/IPv6
print-ipfc.c Have print_llc() clear out the extracted_ethertype argument, rather than
print-ipnet.c Convert the IPv6 printer to use netdissect.
print-ipx.c Print IPX network numbers as 8 hex digits, as we do elsewhere.
print-isakmp.c "sa_len" is, on some platforms, #defined to something else; use
print-isoclns.c Fix some errors.
print-juniper.c Convert the IPv6 printer to use netdissect.
print-krb.c Have the configure script arrange that the Makefile define _U_
print-l2tp.c Just use a u_char * to go through the packet data; don't try to be
print-lane.c Use the ndo argument to lane_hdr_print().
print-ldp.c Add some attribute/TLV length checks.
print-llc.c reworked print-ether to use netdissect
print-lldp.c As we're always printing "LLDP, length XXX", don't do it for the syst…
print-lmp.c Fix a bunch of "sizeof(sizeof(XXX))".
print-lspping.c Fix a bunch of "sizeof(sizeof(XXX))".
print-lwapp.c Get rid of unused (but set) variable.
print-lwres.c Add length checks.
print-mobile.c Go with Wireshark's Internet checksum routine.
print-mobility.c Get rid of an unused variable.
print-mpcp.c complete the outstanding opcodes for MPCP & add boundary checks
print-mpls.c Convert the IPv6 printer to use netdissect.
print-msdp.c refactored ip_print() so that chained header parser (ESP/AH) can
print-netbios.c Have the configure script arrange that the Makefile define _U_
print-nfs.c Enhance NFS access request messages.
print-ntp.c The peer polling interval is an exponent; treat it as such.
print-null.c Convert the IPv6 printer to use netdissect.
print-olsr.c Fix up length checking for the MID message to check before *each*
print-ospf.c Constify some arguments.
print-ospf6.c Redo length checks in ospf6_print_lsa().
print-pflog.c ip6_print() now takes a netdissect_options pointer as its first argum…
print-pgm.c Add ACK decoding and add PGMCC DATA and FEEDBACK options.
print-pim.c spelling fixes
print-ppi.c Declare all local variables before any executable statements.
print-ppp.c Convert the IPv6 printer to use netdissect.
print-pppoe.c Get rid of unnecessary initialization.
print-pptp.c remove redundant TRUE|FALSE defs
print-radius.c Don't set the length of the attributes based on the snapshot length,
print-raw.c Have the configure script arrange that the Makefile define _U_
print-rip.c decode RIPv2 authentication up to RFC4822
print-ripng.c From Gisle Vanem: don't do the IN6_IS_ADDR_UNSPECIFIED stuff unless it's
print-rpki-rtr.c Get rid of another zero-length array.
print-rrcp.c 0x%02d is silly - 0x means "hex", so it should be 0x%02x.
print-rsvp.c Fix a bunch of "sizeof(sizeof(XXX))".
print-rt6.c Get rid of an unused variable.
print-rx.c Fix use of PRIu64.
print-sctp.c RESEND: [PATCH 1/1] ForCES fix SCTP TML port
print-sflow.c The ifSpeed field of a generic interface counter in sFlow is 64 bits.
print-sip.c Check that bytes exist in the captured data before fetching them.
print-sl.c Convert the IPv6 printer to use netdissect.
print-sll.c reworked print-ether to use netdissect
print-slow.c Fix a bunch of "sizeof(sizeof(XXX))".
print-smb.c SMB-over-TCP (port 445) support.
print-snmp.c Add an "fn_printzp()" routine for printing null-padded strings (strings
print-stp.c Bugfix from Carles Kishimoto <carles.kishimoto@gmail.com>:
print-sunatm.c Fix up a bunch of comments - the on-the-wire length field in a
print-sunrpc.c Handle systems with getrpcbynumber() but no header file for it.
print-symantec.c reworked print-ether to use netdissect
print-syslog.c add support for syslog
print-tcp.c Add a routine to do the "checksum with pseudo-header" stuff for IPv4.
print-telnet.c pass on ident string to hex_print()
print-tftp.c Clean up handling of tftp.h.
print-timed.c Have the configure script arrange that the Makefile define _U_
print-tipc.c Put the addresses early in the message format, and handle short messa…
print-token.c Add some bounds checks for the source routing information.
print-udld.c From Carles Kishimoto <carles.kishimoto@gmail.com>:
print-udp.c Add "radius" as an option for -T.
print-usb.c Handle the 48-byte and 64-byte Linux USB headers differently; for now,
print-vjc.c cleaned up warning.
print-vqp.c Squelch compiler warning.
print-vrrp.c Go with Wireshark's Internet checksum routine.
print-vtp.c From Carles Kishimoto <carles.kishimoto@gmail.com>:
print-wb.c Improve the bounds checking.
print-zephyr.c squelch compiler warnings
route6d.h The "__attribute__((packed))" tag on structures causes some files not to
rpc_auth.h Get rid of the multiple-include protection in our RPC headers, so we
rpc_msg.h Get rid of the multiple-include protection in our RPC headers, so we
rx.h The "__attribute__((packed))" tag on structures causes some files not to
sctpConstants.h The SCTP dissector is only called for SCTP packets, so there's no reason
sctpHeader.h The "__attribute__((packed))" tag on structures causes some files not to
send-ack.awk Initial revision
setsignal.c Have the configure script arrange that the Makefile define _U_
setsignal.h Initial revision
signature.c signature.h/c: mark several structs as const
signature.h signature.h/c: mark several structs as const
slcompress.h Get rid of a couple of #defines not used by tcpdump.
slip.h Pull the "linux-include" versions of "slip.h" and "slcompress.h" up to
sll.h Fix a bunch of references to tcpdump-workers@tcpdump.org to refer to the
smb.h Correctly handle Unicode strings - skip padding to put them on a 2-byte
smbutil.c smbutil.c: mark several structs as const
stime.awk Initial revision
strcasecmp.c strcasecmp.c: mark array as const
tcp.h add support for the RPKI/Router Protocol as per draft-ietf-sidr-rpki-…
tcpdump-stdinc.h Mark various IPv4 and IPv6 headers as unaligned.
tcpdump.1.in Merge branch 'master' of git+ssh://bpf.tcpdump.org/tcpdump/master/git…
tcpdump.c Squelch some warnings, and add some comments to clarify the code path.
telnet.h Patches from NetBSD tree.
tftp.h Redefined ERROR into TFTP_ERROR, as ERROR is already defined in the
timed.h
token.h Don't directly fetch multi-byte integers from packets.
udp.h For Babel, recognise both UDP/6696 and UDP/6697.
util.c Squelch a warning, style normalization.
vfprintf.c Have the configure script arrange that the Makefile define _U_

README

@(#) $Header: /tcpdump/master/tcpdump/README,v 1.68 2008-12-15 00:05:27 guy Exp $ (LBL)

TCPDUMP 4.x.y
Now maintained by "The Tcpdump Group"
See 		www.tcpdump.org

Please send inquiries/comments/reports to:
	tcpdump-workers@lists.tcpdump.org

Anonymous Git is available via:
	git clone git://bpf.tcpdump.org/tcpdump

Version 4.x.y of TCPDUMP can be retrieved with the CVS tag "tcpdump_4_xrely":
	cvs -d :pserver:cvs.tcpdump.org:/tcpdump/master checkout -r tcpdump_4_xrely tcpdump

Please submit patches against the master copy to the tcpdump project on
sourceforge.net.

formerly from 	Lawrence Berkeley National Laboratory
		Network Research Group <tcpdump@ee.lbl.gov>
		ftp://ftp.ee.lbl.gov/tcpdump.tar.Z (3.4)

This directory contains source code for tcpdump, a tool for network
monitoring and data acquisition.  This software was originally
developed by the Network Research Group at the Lawrence Berkeley
National Laboratory.  The original distribution is available via
anonymous ftp to ftp.ee.lbl.gov, in tcpdump.tar.Z.  More recent
development is performed at tcpdump.org, http://www.tcpdump.org/

Tcpdump uses libpcap, a system-independent interface for user-level
packet capture.  Before building tcpdump, you must first retrieve and
build libpcap, also originally from LBL and now being maintained by
tcpdump.org; see http://www.tcpdump.org/ .

Once libpcap is built (either install it or make sure it's in
../libpcap), you can build tcpdump using the procedure in the INSTALL
file.

The program is loosely based on SMI's "etherfind" although none of the
etherfind code remains.  It was originally written by Van Jacobson as
part of an ongoing research project to investigate and improve tcp and
internet gateway performance.  The parts of the program originally
taken from Sun's etherfind were later re-written by Steven McCanne of
LBL.  To insure that there would be no vestige of proprietary code in
tcpdump, Steve wrote these pieces from the specification given by the
manual entry, with no access to the source of tcpdump or etherfind.

Over the past few years, tcpdump has been steadily improved by the
excellent contributions from the Internet community (just browse
through the CHANGES file).  We are grateful for all the input.

Richard Stevens gives an excellent treatment of the Internet protocols
in his book ``TCP/IP Illustrated, Volume 1''. If you want to learn more
about tcpdump and how to interpret its output, pick up this book.

Some tools for viewing and analyzing tcpdump trace files are available
from the Internet Traffic Archive:

	http://www.acm.org/sigcomm/ITA/

Another tool that tcpdump users might find useful is tcpslice:

	ftp://ftp.ee.lbl.gov/tcpslice.tar.Z

It is a program that can be used to extract portions of tcpdump binary
trace files. See the above distribution for further details and
documentation.

Problems, bugs, questions, desirable enhancements, etc. should be sent
to the address "tcpdump-workers@lists.tcpdump.org".  Bugs, support
requests, and feature requests may also be submitted on the SourceForge
site for tcpdump at

	http://sourceforge.net/projects/tcpdump/

Source code contributions, etc. should be sent to the email address
submitted as patches on the SourceForge site for tcpdump.

Current versions can be found at www.tcpdump.org, or the SourceForge
site for tcpdump.

 - The TCPdump team

original text by: Steve McCanne, Craig Leres, Van Jacobson

-------------------------------------
This directory also contains some short awk programs intended as
examples of ways to reduce tcpdump data when you're tracking
particular network problems:

send-ack.awk
	Simplifies the tcpdump trace for an ftp (or other unidirectional
	tcp transfer).  Since we assume that one host only sends and
	the other only acks, all address information is left off and
	we just note if the packet is a "send" or an "ack".

	There is one output line per line of the original trace.
	Field 1 is the packet time in decimal seconds, relative
	to the start of the conversation.  Field 2 is delta-time
	from last packet.  Field 3 is packet type/direction.
	"Send" means data going from sender to receiver, "ack"
	means an ack going from the receiver to the sender.  A
	preceding "*" indicates that the data is a retransmission.
	A preceding "-" indicates a hole in the sequence space
	(i.e., missing packet(s)), a "#" means an odd-size (not max
	seg size) packet.  Field 4 has the packet flags
	(same format as raw trace).  Field 5 is the sequence
	number (start seq. num for sender, next expected seq number
	for acks).  The number in parens following an ack is
	the delta-time from the first send of the packet to the
	ack.  A number in parens following a send is the
	delta-time from the first send of the packet to the
	current send (on duplicate packets only).  Duplicate
	sends or acks have a number in square brackets showing
	the number of duplicates so far.

	Here is a short sample from near the start of an ftp:
		3.00    0.20   send . 512
		3.20    0.20    ack . 1024  (0.20)
		3.20    0.00   send P 1024
		3.40    0.20    ack . 1536  (0.20)
		3.80    0.40 * send . 0  (3.80) [2]
		3.82    0.02 *  ack . 1536  (0.62) [2]
	Three seconds into the conversation, bytes 512 through 1023
	were sent.  200ms later they were acked.  Shortly thereafter
	bytes 1024-1535 were sent and again acked after 200ms.
	Then, for no apparent reason, 0-511 is retransmitted, 3.8
	seconds after its initial send (the round trip time for this
	ftp was 1sec, +-500ms).  Since the receiver is expecting
	1536, 1536 is re-acked when 0 arrives.

packetdat.awk
	Computes chunk summary data for an ftp (or similar
	unidirectional tcp transfer). [A "chunk" refers to
	a chunk of the sequence space -- essentially the packet
	sequence number divided by the max segment size.]

	A summary line is printed showing the number of chunks,
	the number of packets it took to send that many chunks
	(if there are no lost or duplicated packets, the number
	of packets should equal the number of chunks) and the
	number of acks.

	Following the summary line is one line of information
	per chunk.  The line contains eight fields:
	   1 - the chunk number
	   2 - the start sequence number for this chunk
	   3 - time of first send
	   4 - time of last send
	   5 - time of first ack
	   6 - time of last ack
	   7 - number of times chunk was sent
	   8 - number of times chunk was acked
	(all times are in decimal seconds, relative to the start
	of the conversation.)

	As an example, here is the first part of the output for
	an ftp trace:

	# 134 chunks.  536 packets sent.  508 acks.
	1       1       0.00    5.80    0.20    0.20    4       1
	2       513     0.28    6.20    0.40    0.40    4       1
	3       1025    1.16    6.32    1.20    1.20    4       1
	4       1561    1.86    15.00   2.00    2.00    6       1
	5       2049    2.16    15.44   2.20    2.20    5       1
	6       2585    2.64    16.44   2.80    2.80    5       1
	7       3073    3.00    16.66   3.20    3.20    4       1
	8       3609    3.20    17.24   3.40    5.82    4       11
	9       4097    6.02    6.58    6.20    6.80    2       5

	This says that 134 chunks were transferred (about 70K
	since the average packet size was 512 bytes).  It took
	536 packets to transfer the data (i.e., on the average
	each chunk was transmitted four times).  Looking at,
	say, chunk 4, we see it represents the 512 bytes of
	sequence space from 1561 to 2048.  It was first sent
	1.86 seconds into the conversation.  It was last
	sent 15 seconds into the conversation and was sent
	a total of 6 times (i.e., it was retransmitted every
	2 seconds on the average).  It was acked once, 140ms
	after it first arrived.

stime.awk
atime.awk
	Output one line per send or ack, respectively, in the form
		<time> <seq. number>
	where <time> is the time in seconds since the start of the
	transfer and <seq. number> is the sequence number being sent
	or acked.  I typically plot this data looking for suspicious
	patterns.


The problem I was looking at was the bulk-data-transfer
throughput of medium delay network paths (1-6 sec.  round trip
time) under typical DARPA Internet conditions.  The trace of the
ftp transfer of a large file was used as the raw data source.
The method was:

  - On a local host (but not the Sun running tcpdump), connect to
    the remote ftp.

  - On the monitor Sun, start the trace going.  E.g.,
      tcpdump host local-host and remote-host and port ftp-data >tracefile

  - On local, do either a get or put of a large file (~500KB),
    preferably to the null device (to minimize effects like
    closing the receive window while waiting for a disk write).

  - When transfer is finished, stop tcpdump.  Use awk to make up
    two files of summary data (maxsize is the maximum packet size,
    tracedata is the file of tcpdump tracedata):
      awk -f send-ack.awk packetsize=avgsize tracedata >sa
      awk -f packetdat.awk packetsize=avgsize tracedata >pd

  - While the summary data files are printing, take a look at
    how the transfer behaved:
      awk -f stime.awk tracedata | xgraph
    (90% of what you learn seems to happen in this step).

  - Do all of the above steps several times, both directions,
    at different times of day, with different protocol
    implementations on the other end.

  - Using one of the Unix data analysis packages (in my case,
    S and Gary Perlman's Unix|Stat), spend a few months staring
    at the data.

  - Change something in the local protocol implementation and
    redo the steps above.

  - Once a week, tell your funding agent that you're discovering
    wonderful things and you'll write up that research report
    "real soon now".
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