sc_prefixscan1

Usage

Overview

The sc_prefixscan utility provides the ability to connect to a running scamper(1) instance and use it to collect data to infer if an IPv4 link is likely a point-to-point link using the prefixscan method. An address B is the in-bound interface of a router in a traceroute path if we find an alias A' of the address A returned for the previous hop and A' is a /31 or /30 mate of B, i.e. the link between A and B is a point-to-point link. The prefixscan method infers A and A' are aliases if the IPIDs in responses to five alternating probes sent one second apart monotonically increase and differ by no more than 1,000, or probes to A and A' elicit responses with a common source address. The first technique is a pairwise comparison similar to Ally, and the second is the Mercator technique. The supported options to sc_prefixscan are as follows:

-D

causes sc_prefixscan to detach and become a daemon.

-i infile

specifies a file containing a list of IPv4 address pairs adjacent in traceroute paths to test if they are point-to-point links.

-o outfile

specifies the name of the output file to be written during the data collection phase. The output file will use the warts(5) format.

-p port

specifies the port on the local host where scamper(1) is accepting control socket connections.

-l logfile

specifies the name of a file to log progress output from sc_prefixscan generated at run time.

-r data-file

specifies the name of the data file to be parsed for point-to-point link inferences that were collected by sc_prefixscan in a previous data collection.

-U unix-socket

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

-w wait

specifies the length of time in seconds to wait between probing the same IPv4 address with different methods. By default, sc_prefixscan waits five seconds between methods.

-x prefixlen

specifies the maximum size of prefix to consider. By default, sc_prefixscan considers up to an IPv4 /30 prefix.

Examples

Given a traceroute with the following path:

traceroute to 192.0.30.64

1 192.0.2.1

2 192.0.32.10

3 192.0.31.8

4 192.0.30.64

then to collect data to infer if the implied IPv4 links are point-to-point, put the links in a file named infile.txt formatted as follows:

192.0.2.1 192.0.32.10

192.0.32.10 192.0.31.8

192.0.31.8 192.0.30.64

and use a scamper(1) daemon listening on port 31337 using:

sc_prefixscan -i infile.txt -o outfile.warts -p 31337

To obtain the inferred point-to-point links from outfile.warts:

sc_prefixscan -r outfile.warts