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SC_TRACEDIFF(1)		  BSD General Commands Manual	       SC_TRACEDIFF(1)

NAME
     sc_tracediff -- display traceroute	paths where the	path has changed.

SYNOPSIS
     sc_tracediff [-a] [-m method] [-n]	file1.warts file2.warts

DESCRIPTION
     The sc_tracediff utility displays pairs of	traceroutes to a destination
     where the path has	changed.  It takes two warts files as input and	dis-
     plays paths where a hop differs by	its address.  The options are as fol-
     lows:

     -a	     dump all traceroute pairs regardless of whether they have
	     changed.

     -m	method
	     specifies the method used to match	pairs of traceroutes together.
	     If	dst is specified, traceroutes are matched if the destination
	     IP	address	of both	traces are the same.  If userid	is specified,
	     traceroutes are matched if	the userid field of both traces	are
	     the same.	If dstuserid is	specified, traceroutes are matched if
	     the destination IP	address	and userid fields are the same.	 By
	     default, the destination IP address is used.

     -n	     names should be reported instead of IP addresses, where possible.

     sc_tracediff can be useful	in network monitoring to identify when a for-
     ward IP path has changed.	In this	scenario, it is	recommended that Paris
     traceroute	is used	with the same UDP source and destination ports for
     each execution of scamper so that only paths that have changed are	iden-
     tified, not merely	alternate paths	visible	due to per-flow	load-balanc-
     ing.  By default scamper uses a source port based on the process ID,
     which will	change with each execution of scamper.

EXAMPLES
     The command:

	scamper	-O warts -o file1.warts	-c 'trace -P udp-paris -s 31337' -f
	list.txt

     collects the forward IP paths towards a set of IP addresses found in
     list.txt using 31337 as the UDP source port value.	 If the	above command
     is	adjusted to subsequently collect file2.warts, then we can identify
     paths that	have subsequently changed with the command:

	sc_tracediff file1.warts file2.warts

     If	Paris traceroute with ICMP probes is preferred,	then the following in-
     vocation of scamper is appropriate:

	scamper	-O warts -o file1.warts	-c 'trace -P icmp-paris	-d 31337' -f
	list.txt

     In	this case, scamper uses	31337 as the ICMP checksum value in each
     probe.

SEE ALSO
     scamper(1),

     B.	Augustin, X. Cuvellier,	B. Orgogozo, F.	Viger, T. Friedman, M. Latapy,
     C.	Magnien, and R.	Teixeira, Avoiding traceroute anomalies	with Paris
     traceroute, Proc. ACM/SIGCOMM Internet Measurement	Conference 2006.

AUTHOR
     sc_tracediff was written by Matthew Luckie	<mjl@luckie.org.nz>.

BSD				April 21, 2011				   BSD

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHOR

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