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SC_TBITPMTUD(1)		FreeBSD	General	Commands Manual	       SC_TBITPMTUD(1)

     sc_tbitpmtud -- scamper driver to test systems for	responsiveness to ICMP
     packet too	big messages

     sc_tbitpmtud [-r] [-a address-file] [-c completed-file]
		  [-l limit-per-file] [-m maximum-transmission-unit]
		  [-o output-file] [-p scamper-port] [-t log-file] [-w window]

     sc_tbitpmtud [-d dump-id] [-A ip2as-file] [-m maximum-transmission-unit]
		  [file	...]

     The sc_tbitpmtud utility provides the ability to connect to a running
     scamper(1)	instance and use that instance to test end systems for their
     ability to	perform	Path MTU Discovery, with the output written to a file
     in	warts format.  sc_tbitpmtud first tests	a given	system for responsive-
     ness to ICMP echo packets,	and then tests the given system's TCP stack
     response to ICMP packet too big messages.

     The options are as	follows:

     -?	     prints a list of command line options and a synopsis of each.

     -a	address-file
	     specifies the name	of the input file which	consists of a sequence
	     of	systems	to test, one system per	line.

     -A	ip2as-file
	     specifies the name	of a file which	consists of a mapping of pre-
	     fixes to ASes, one	prefix per line.

     -c	completed-file
	     specifies the name	of a file to record IP addresses that have
	     been tested.

     -d	dump-id
	     specifies the dump	ID to use to analyze the collected data.  Cur-
	     rently, ID	values 1 (mssresults) and 2 (asnresults) are valid,
	     which report PMTUD	behaviour according to the server's MSS	or the
	     server's origin ASN.

     -l	limit-per-file
	     specifies the number of tbit objects to record per	warts file,
	     before opening a new file and placing new objects.

     -m	maximum	transmission unit
	     specifies the pseudo maximum transmission unit to use.  The
	     available choices are 0, 256, 576,	1280, 1480.  If	0 is chosen,
	     sc_tbitpmtud will test each website with all available MTU
	     choices in	decreasing size.  The default MTU value	tested is

     -o	output-file
	     specifies the name	of the file to be written.  The	output file
	     will use the warts	format.

     -p	scamper-port
	     specifies the port	on the local host where	scamper(1) is accept-
	     ing control socket	connections.

     -r	     shuffle the order in which	websites are tested.

     -t	log-file
	     specifies the name	of a file to log progress output from
	     sc_tbitpmtud generated at run time.

     -w	window-size
	     specifies the maximum number of tests to conduct in parallel.
	     The window	size value depends on the value	of the -F parameter
	     passed to the scamper(1) instance.

     Use of this driver	requires a scamper(1) instance listening on a port for
     commands with a configured	firewall.  The following invocation uses
     ipfw(8) firewall rules 1 to 100, with a corresponding window size of 100,
     and an unrestricted packets per second rate, as follows:

	   scamper -P 31337 -F ipfw:1-100 -w 100 -p 0

     To	test a set of web servers specified in a file named webservers.txt and
     formatted as follows:

	1, 5063
	1, 5063 2001:DB8::1
	1, 5063 2001:DB8::2

     the following command will	test all servers for responsiveness to ICMP
     packet too	big messages and record	raw data into webservers_00.warts,
     webservers_01.warts, etc:

	   sc_tbitpmtud	-a webservers.txt -p 31337 -o webservers

     The webservers.txt	file is	required to be formatted as above.  The	format
     is: numeric ID to pass to tbit, a label for the webserver,	the size of
     the object	to be fetched, the IP address to contact, and the URL to use.

     To	characterize PMTUD behaviour according to the server's advertised MSS

	   sc_tbitpmtud	-d mssresults webservers_*.warts

     Given files with IPv4 prefixes in prefix2as4.txt and IPv6 prefixes	in
     prefix2as6.txt formatted as follows:

	2001:DB8::     48     64496
	2001:DB8:1::   48     64497      24     64498

     the following command will	characterize PMTUD behaviour according to the
     origin ASN	of the server:

	   sc_tbitpmtud	-d asnresults -A prefix2as4.txt	-A prefix2as6.txt

     scamper(1), sc_wartsdump(1), sc_warts2json(1), warts(5),

     M.	Luckie and B. Stasiewicz, Measuring Path MTU Discovery Behaviour,
     Proc. ACM/SIGCOMM Internet	Measurement Conference 2010.

     A.	Medina,	M. Allman, and S. Floyd, Measuring Interactions	between
     Transport Protocols and Middleboxes, Proc.	ACM/SIGCOMM Internet
     Measurement Conference 2004.

     sc_tbitpmtud was written by Matthew Luckie	<>.  Ben
     Stasiewicz	contributed an initial implementation of the Path MTU Discov-
     ery TBIT test to scamper, building	on the work of Medina et al.

FreeBSD	13.0			 March 1, 2018			  FreeBSD 13.0


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