sc_ally man page

sc_ally — scamper driver to run Ally on a list of candidate aliases.


sc_ally [-?D] [-i infile] [-o outfile] [-p port] [-U unix-socket] [-f fudge] [-i probe-wait] [-q attempts] [-t logfile] [-w waittime]


The sc_ally utility provides the ability to connect to a running scamper(1) instance and have a set of IPv4 address-pairs tested for aliases using the Ally technique. For each address pair in the file, sc_ally establishes which probe methods (UDP, TCP-ack, ICMP-echo) solicit an incrementing IP-ID value, and then uses the Ally technique on pairs where a probe method is able to obtain an incrementing IP-ID for both addresses. The output is written to a warts file. The options are as follows:


prints a list of command line options and a synopsis of each.


causes sc_ally to detach and become a daemon.

-i infile

specifies the name of the input file which consists of a sequence of IPv4 address-pairs, one pair per line.

-o outfile

specifies the name of the output file to be written. The output file will use the warts format.

-p port

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

-U unix-socket

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

-f fudge

specifies the fudge factor to use when (1) inferring if IPIDs are assigned from a counter, and (2) inferring if two addresses share the same counter.

-i probe-wait

specifies the inter-probe gap for both ping and Ally measurements, in milliseconds. The default is 1000ms (1 second); the minimum is 200ms, and the maximum is 2000ms.

-q attempts

specifies the number of times to try Ally when one of the addresses is unresponsive.

-t logfile

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

-w waittime

specifies the minimum length of time, in seconds, to wait between completing a measurement to a particular IP address and issuing the next.


Given a set of IPv4-address pairs in a file named infile.txt:

and a scamper(1) daemon listening on port 31337, then these address-pairs can be tested for aliases using

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

See Also

N. Spring, R. Mahajan, and D. Wetherall, Measuring ISP topologies with Rocketfuel, Proc. ACM SIGCOMM 2002.

scamper(1), sc_wartsdump(1), sc_warts2text(1)


sc_ally is written by Matthew Luckie <>.

Referenced By

scamper(1), sc_speedtrap(1).

March 1, 2011