golding@terra.ucsc.edu (Richard Golding) (04/30/91)
At UC Santa Cruz we are conducting a series of measurements of the
Internet, as part of a project to understand how to build efficient
wide-area applications (and not incidentally as part of my MS thesis
work). As a part of these measurements, we need to obtain traces of
communication failure rates and latency.
If you are at a site on the Internet which can send and receive UDP
packets to and from UCSC, we need your assistance.(1)
We are asking that people at several sites throughout the Internet run
a simple daemon for two weeks, from Thursday, 2 May 1991 through
Thursday, 16 May 1991. We will be sending this daemon a UDP packet a
few times each day. The daemon simply echoes this packet back to the
sender, so we can time how long it takes.
The source for this daemon is enclosed in this message, and should
take less than five minutes to install. We're providing the source
code so you can look it over and convince yourself it doesn't pose a
significant load or security risk for your machine. (More on this in
the installation instructions.)
The daemon runs on Sun3 and Sun4 systems under SunOS 4.x, and on
HP9000 systems under HPUX 7.0.
The attached shar file contains a C program, makefile, wand
installation instructions. The installation involves compiling the
program, adding the program to crontab (or some other mechanism to
ensure it runs regularly), and sending mail to us informing us of your
host, port, and organization.
If you have concerns or questions, please feel free to contact us.
Thank you.
Richard Golding
Graduate Student, Computer & Info Sciences
Baskin Center for CE&IS
University of California
Santa Cruz, CA 95064
(408) 458-3613
Internet: golding@cis.ucsc.edu, or
golding@cello.hpl.hp.com, or
golding@slice.ooc.uva.nl
(1) This rules out sites inside several companies, such as HP, Sun,
and Apple, which do not pass certain classes of traffic from the
outside.
---- Cut Here and unpack ----
#!/bin/sh
# shar: Shell Archiver (v1.22)
# Packed Mon Apr 29 15:27:15 PDT 1991 by midgard!golding
# from directory /terra/a/grads/golding/evrep/validate/distrib
#
# Run the following text with /bin/sh to create:
# INSTRUCTIONS
# Makefile
# udptestd.c
# validate.h
#
if test -f INSTRUCTIONS; then echo "File INSTRUCTIONS exists"; else
echo "x - extracting INSTRUCTIONS (Text)"
sed 's/^X//' << 'SHAR_EOF' > INSTRUCTIONS &&
XInstallation instructions
X-------------------------
X
XThese instructions have been verified for Sun3 and Sun4 systems
Xrunning SunOS 4.x, and for HP9000/800 systems running HPUX 7.0. They
Xmay work on other systems; however, I don't guarantee anything. If
Xyou have problems please mail golding@cis.ucsc.edu and we'll try to
Xwork it out. They are known _not_ to work for Ultrix and BSD 4.3
Xsystems, because these systems do not allow individual crontab files.
X
X1. Unpack the shar file into an otherwise empty directory.
X
X2. Configure the test daemon to use the proper UDP port. By default
Xthe daemon uses port 4296, an unprivileged, unreserved port. If this
Xconflicts with some other daemon on your system, change the port by
Xediting the third line in the Makefile:
X
X CFLAGS = -DUDPPORT=<new UDP port number>
X
X3. Compile the daemon by typing
X
X make
X
X4. Add an entry to your crontab to ensure that the daemon continues
Xto run by editing your current crontab. If you are on a SunOS system,
Xyou can edit your crontab entry using the command:
X
X crontab -e
X
XOn HPUX and similar systems you will need to save your current crontab
Xinto a file, edit that file, and reset your crontab from that file:
X
X crontab -l >file
X (edit) file
X crontab file
X
XYou should add an entry of the form:
X
X 5,20,35,50 * * 4,5 * $DIR/udptestd > /dev/null 2>&1
X
Xreplacing `$DIR' with the path for the directory in which you
Xinstalled the daemon.
X
X5. Send mail to golding@cis.ucsc.edu with the following information:
X
X - The (full) name of the host on which the daemon is being run
X (e.g. sequoia.ucsc.edu)
X - The UDP port number the daemon will use (default is 4296)
X - The host type (e.g. Sun 4/20 using SunOS 4.1.1, or VAX 11/780
X using BSD4.3 Unix)
X - A name and organization to be credited in the thesis (or an
X indication you prefer to remain anonymous)
X
X I'd also appreciate comments on how long it took you to install
X this software, and if it posed any particular problems.
X
XThat's all there is.
X
X
XCleaning up after the experiment
X--------------------------------
X
XThe measurement experiment is scheduled to last two weeks, from 2 May
X1991 through 16 May 1991. To allow for problems, I'd ask that you
Xkeep the measurement daemon running through 1 June 1991.
X
XAfter the experiment is over, you will need to do two things to clean
Xup:
X
X1. Remove the entry from your crontab. On a SunOS 4.x system, use
Xthe command
X crontab -e
Xto edit your crontab file, and delete the line
X 5,20,35,50 * * 4,5 * <directory>/udptest > /dev/null 2>&1
Xwhich was added by step 5 in the installation.
X
XOn an HPUX or similar system, you will need save your crontab to a
Xfile, edit the file, and reset your crontab from the file. The
Xcommands are the same as were used in the last section to add the line
Xto your crontab.
X
X2. Delete the directory containing the daemon and all its contents.
X
XSecurity considerations
X-----------------------
X
XWe believe that this program is neither a security nor performance
Xproblem. However, we're sending out the source code so you can look
Xat it for yourself. If you feel there is a problem, don't use it.
X
XThe daemon uses an unprivileged UDP port for communication. You
Xshould choose the port number so that it doesn't conflict with
Xanything else on your system. The default is probably fine, but you
Xshould check.
X
XCare has been taken that it does not require root privileges either to
Xrun or for installation. I would recommend _not_ installing it as
Xroot. It uses a crontab entry to ensure that it will be run following
Xa system restart, rather than requiring that it be added to the
Xsystem's startup configuration.
X
XThe daemon neither writes nor reads files, so there is no
Xpossibility of the daemon using file system space beyond what is
Xrequired for the source and binary.
X
XThe only resources this daemon uses are the memory required to run it,
Xand a trivial amount per message. We will be sending a few messages
Xeach day -- on the order of 800 per day (11 messages, three times an
Xhour) -- so the daemon should not interfere with normal operations.
X(We found that it added no measurable load to a local Sun4 system, as
Xmeasured by the kernel's 1-, 5-, and 15-minute load averages.)
X
X-----
X
XA technical report on some preliminary work on this problem is
Xavailable as TR # UCSC-CRL-91-01, and can be obtained by ftp from
Xmidgard.ucsc.edu in the file pub/tr/ucsc-crl-91-01.ps.Z .
X
XThank you for your assistance is this experiment.
X
XRichard Golding
Xgolding@cis.ucsc.edu
XConcurrent Systems Lab
XBaskin Center for Computer Engr. & Info. Sci.
XApplied Sciences Building
XUniversity of California
XSanta Cruz CA 95064
SHAR_EOF
chmod 0444 INSTRUCTIONS || echo "restore of INSTRUCTIONS fails"
fi
if test -f Makefile; then echo "File Makefile exists"; else
echo "x - extracting Makefile (Text)"
sed 's/^X//' << 'SHAR_EOF' > Makefile &&
XLIBS =
XCFLAGS = -DUDPPORT=4296 # -DDEBUG
XPROGS = udptestd
X
Xall: $(PROGS)
X
Xudptestd: udptestd.o
X cc -o udptestd udptestd.o $(LIBS)
X
Xudptestd.o: udptestd.c validate.h
X
Xclean:
X -rm -f *.o core *~
X
Xspotless: clean
X -rm -f $(PROGS)
SHAR_EOF
chmod 0444 Makefile || echo "restore of Makefile fails"
fi
if test -f udptestd.c; then echo "File udptestd.c exists"; else
echo "x - extracting udptestd.c (Text)"
sed 's/^X//' << 'SHAR_EOF' > udptestd.c &&
X#include <sys/types.h>
X#include <sys/time.h>
X#include <sys/socket.h>
X#include <netinet/in.h>
X#include <netdb.h>
X#include <stdio.h>
X#include "validate.h"
X
X#ifdef DEBUG
Xchar *
Xhostnameof(sa)
Xstruct sockaddr_in *sa;
X{
X struct hostent *h;
X
X h = gethostbyaddr(sa->sin_addr,sizeof(struct in_addr),AF_INET);
X return h->h_name;
X}
X
Xint
Xportof(sa)
Xstruct sockaddr_in *sa;
X{
X return ntohl(sa->sin_port);
X}
X#endif
X
Xvoid
Xgettimestamp(ps,pus)
Xint *ps, *pus;
X{
X struct timeval t;
X
X gettimeofday(&t, NULL);
X *ps = htonl(t.tv_sec);
X *pus = htonl(t.tv_usec);
X}
X
Xvoid
Xdoecho(sock)
Xint sock;
X{
X req inreq;
X int len;
X int flags;
X struct sockaddr_in from;
X int fromlen;
X int rc;
X rep outrep;
X
X /* get a request message */
X#ifdef DEBUG
X printf("waiting for message\n");
X#endif
X len = sizeof(inreq);
X fromlen = sizeof(from);
X flags = 0;
X rc = recvfrom(sock, &inreq, len, flags, (struct sockaddr *)&from, &fromlen);
X if (rc < 0) {
X perror("In recvfrom");
X return;
X }
X
X /* process it: grab a timestamp, fill out reply, and sleep */
X#ifdef DEBUG
X printf("got message: from host [%s] port %d, sequence %d, delay %d\n",
X hostnameof(&from),portof(&from),ntohl(inreq.seq),ntohl(inreq.delaytime));
X#endif
X outrep.seq = inreq.seq;
X outrep.delaytime = inreq.delaytime;
X gettimestamp(&outrep.tinsec, &outrep.tinusec);
X sleep(ntohl(inreq.delaytime));
X
X /* done processing, grab another timestamp and reply */
X gettimestamp(&outrep.toutsec, &outrep.toutusec);
X sendto(sock,&outrep,sizeof(outrep),0,&from,sizeof(from));
X}
X
Xmain()
X{
X int sock;
X int length;
X struct sockaddr_in name;
X
X /* create socket from which to read */
X sock = socket(AF_INET, SOCK_DGRAM, 0);
X if (sock < 0) {
X perror("opening datagram socket");
X exit(-1);
X }
X
X /* create name and bind */
X name.sin_family = AF_INET;
X name.sin_addr.s_addr = INADDR_ANY;
X name.sin_port = UDPPORT;
X if (bind(sock, &name, sizeof(name))) {
X perror("binding datagram socket");
X exit(-2);
X }
X
X /* check port value */
X length = sizeof(name);
X if (getsockname(sock, &name, &length)) {
X perror("getting socket name");
X exit(-3);
X }
X#ifdef DEBUG
X printf("Socket has port #%d\n",ntohs(name.sin_port));
X#endif
X
X for (;;) {
X doecho(sock);
X }
X
X /* NOTREACHED */
X}
SHAR_EOF
chmod 0444 udptestd.c || echo "restore of udptestd.c fails"
fi
if test -f validate.h; then echo "File validate.h exists"; else
echo "x - extracting validate.h (Text)"
sed 's/^X//' << 'SHAR_EOF' > validate.h &&
Xtypedef struct _req {
X int seq;
X int delaytime;
X} req;
X
Xtypedef struct _rep {
X int seq;
X int delaytime;
X int tinsec, tinusec, toutsec, toutusec;
X} rep;
SHAR_EOF
chmod 0444 validate.h || echo "restore of validate.h fails"
fi
exit 0
Richard A. Golding golding@cello.hpl.hp.com or
UC Santa Cruz CIS Board (grad student) golding@cis.ucsc.edu (best) or
golding@slice.ooc.uva.nl
Post: Baskin Centre for CE & IS, Appl. Sci. Bldg., UC, Santa Cruz CA 95064
--
=========================== MODERATOR ==============================
Steve Stevenson {steve,fpst}@hubcap.clemson.edu
Department of Computer Science, comp.parallel
Clemson University, Clemson, SC 29634-1906 (803)656-5880.mabell