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
is written by Matthew Luckie
<mjl@luckie.org.nz>.