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 displays paths where a hop differs by its address.  The options are as
       follows:

       -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 forward 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 identified, not  merely  alternate
       paths visible due to per-flow load-balancing.  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  invocation 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>.

Debian                                           April 21, 2011                                  SC_TRACEDIFF(1)