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SC_ALLY(1)		FreeBSD	General	Commands Manual		    SC_ALLY(1)

     sc_ally --	scamper	driver to run Ally on a	list of	candidate aliases.

     sc_ally [-?D] [-a infile] [-o outfile] [-p	port] [-U unix-socket]
	     [-f fudge]	[-i probe-wait]	[-O options] [-q attempts]
	     [-t logfile] [-w waittime]

     sc_ally [-d dump-id] [-O options] [file ...]

     The sc_ally utility provides the ability to connect to a running
     scamper(1)	instance and have a set	of IPv4	address	sets tested for
     aliases using the Ally technique.	For each address pair on a single line
     in	the file, sc_ally establishes which probe methods (UDP,	TCP-ack, ICMP-
     echo) solicit an incrementing IP-ID value,	and then uses the Ally tech-
     nique on pairs where a probe method is able to obtain an incrementing IP-
     ID	for both addresses.  sc_ally can also infer which IP addresses are
     aliases using the Mercator	common source address technique	as a byproduct
     of	the UDP	probing	that sc_ally does.  The	output of sc_ally is written
     to	a warts(5) file, which can then	be processed to	extract	aliases.  The
     options are as follows:

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

     -D	     causes sc_ally to detach and become a daemon.

     -a	infile
	     specifies the name	of the input file which	consists of a sequence
	     of	IPv4 addresses,	one candidate set per line.

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

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

     -U	unix-socket
	     specifies the name	of a unix domain socket	where scamper(1) is
	     accepting control socket connections.

     -d	dump-id
	     specifies the number identifying an analysis to conduct.  The
	     current choices for are 1-3, and are:
	       -  1: dump aliases inferred using the Ally (IPID-based) tech-
	       -  2: dump aliases inferred using the Mercator (common source
		  address based) technique.
	       -  3: dump aliases inferred using both Ally and Mercator	tech-

     -f	fudge
	     specifies the fudge factor	to use when (1)	inferring if IPIDs are
	     assigned from a counter, and (2) inferring	if two addresses share
	     the same counter.	A value	of zero	will cause ally	to infer
	     aliases if	the IPIDs are in a monotonic sequence.

     -i	probe-wait
	     specifies the inter-probe gap for both ping and Ally measure-
	     ments, in milliseconds.  The default is 1000ms (1 second);	the
	     minimum is	200ms, and the maximum is 2000ms.

     -O	options
	     allows the	behavior of sc_ally to be further tailored.  The cur-
	     rent choices for this option are:
	       -  nobs:	do not consider	byte swapped IPID values when infer-
		  ring if IPID values are assigned from	a counter.
	       -  tc: dump transitive closure when reporting aliases.

     -q	attempts
	     specifies the number of probes to use with	Ally.

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

     -w	waittime
	     specifies the minimum length of time, in seconds, to wait between
	     completing	a measurement to a particular IP address and issuing
	     the next.

     Given a set of IPv4-address sets in a file	named infile.txt:

     and a scamper(1) daemon listening on port 31337, then these addresses can
     be	tested for aliases using

     sc_ally -a	infile.txt -o outfile.warts -p 31337

     To	obtain a list of inferred alias	pairs using the	Ally technique from a
     warts(5) file:

     sc_ally -d	1 outfile.warts

     To	obtain a list of inferred routers using	a transitive closure of	alias
     pairs inferred using the Ally and Mercator	techniques:

     sc_ally -d	3 -O tc	outfile.warts

     scamper(1), sc_radargun(1), sc_wartsdump(1), sc_warts2text(1),

     N.	Spring,	R. Mahajan, and	D. Wetherall, Measuring	ISP topologies with
     Rocketfuel, Proc. ACM SIGCOMM 2002.

     R.	Govindan and H.	Tangmunarunkit,	Heuristics for Internet	Map Discovery,
     Proc. IEEE	INFOCOM	2000.

     A.	Bender,	R. Sherwood, and N. Spring, Fixing Ally's growing pains	with
     velocity modeling,	Proc. ACM/SIGCOMM Internet Measurement Conference

     sc_ally was written by Matthew Luckie <>.

FreeBSD	13.0			  May 4, 2019			  FreeBSD 13.0


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