1SC_TRACEDIFF(1)           BSD General Commands Manual          SC_TRACEDIFF(1)
2

NAME

4     sc_tracediff — display traceroute paths where the path has changed.
5

SYNOPSIS

7     sc_tracediff [-a] [-m method] [-n] file1.warts file2.warts
8

DESCRIPTION

10     The sc_tracediff utility displays pairs of traceroutes to a destination
11     where the path has changed.  It takes two warts files as input and dis‐
12     plays paths where a hop differs by its address.  The options are as fol‐
13     lows:
14
15     -a      dump all traceroute pairs regardless of whether they have
16             changed.
17
18     -m method
19             specifies the method used to match pairs of traceroutes together.
20             If dst is specified, traceroutes are matched if the destination
21             IP address of both traces are the same.  If userid is specified,
22             traceroutes are matched if the userid field of both traces are
23             the same.  If dstuserid is specified, traceroutes are matched if
24             the destination IP address and userid fields are the same.  By
25             default, the destination IP address is used.
26
27     -n      names should be reported instead of IP addresses, where possible.
28
29     sc_tracediff can be useful in network monitoring to identify when a for‐
30     ward IP path has changed.  In this scenario, it is recommended that Paris
31     traceroute is used with the same UDP source and destination ports for
32     each execution of scamper so that only paths that have changed are iden‐
33     tified, not merely alternate paths visible due to per-flow load-balanc‐
34     ing.  By default scamper uses a source port based on the process ID,
35     which will change with each execution of scamper.
36

EXAMPLES

38     The command:
39
40        scamper -O warts -o file1.warts -c 'trace -P udp-paris -s 31337' -f
41        list.txt
42
43     collects the forward IP paths towards a set of IP addresses found in
44     list.txt using 31337 as the UDP source port value.  If the above command
45     is adjusted to subsequently collect file2.warts, then we can identify
46     paths that have subsequently changed with the command:
47
48        sc_tracediff file1.warts file2.warts
49
50     If Paris traceroute with ICMP probes is preferred, then the following
51     invocation of scamper is appropriate:
52
53        scamper -O warts -o file1.warts -c 'trace -P icmp-paris -d 31337' -f
54        list.txt
55
56     In this case, scamper uses 31337 as the ICMP checksum value in each
57     probe.
58

SEE ALSO

60     scamper(1),
61
62     B. Augustin, X. Cuvellier, B. Orgogozo, F. Viger, T. Friedman, M. Latapy,
63     C. Magnien, and R. Teixeira, Avoiding traceroute anomalies with Paris
64     traceroute, Proc. ACM/SIGCOMM Internet Measurement Conference 2006.
65

AUTHOR

67     sc_tracediff is written by Matthew Luckie <mjl@luckie.org.nz>.
68
69BSD                             April 21, 2011                             BSD
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