rfc1739.txt

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Kessler & Shepard                                               [Page 6]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


      ==================================================================
   ** C:\> FINGER [e-mail]
      [smcvax.smcvt.edu]
      KUMQUAT  Gary Kessler            20A02991 MAIL           TXA3
      Last login Fri 15-Jul-1994 2:59 PM-EDT

      Plan:

      -----------------------------------------------------------------
      Gary C. Kessler
      Adjunct Faculty Member, Graduate College

      Senior Member of Technical Staff
      Hill Associates               [phone] or 655-0940 (office)
      17 Roosevelt Highway          [phone] (fax)
      Colchester, VT  05446         [phone] (home)
      INTERNET:  [e-mail] or [e-mail]
      -----------------------------------------------------------------

   ** C:\> FINGER @SMCVAX.SMCVT.EDU
      [smcvax.smcvt.edu]
      Friday, July 15, 1994 4:00PM-EDT   Up 21 03:41:31
      7+0 Jobs on SMCVAX  Load ave  0.24 0.31 0.25

       User    Personal Name       Subsys
      DENIS    Denis Stratford     MAIL
      GOODWIN  Dave Goodwin        RTPAD
      JAT      John Trono          EDT
      KUMQUAT  Gary Kessler        MAIL
      INFO     SMC Info Service    TELNET
      SYSTEM   System Manager      *DCL*
      SMITH    Jim Smith           LYNX

      C:\>
      ================================================================

2.4. TRACEROUTE

   Traceroute is another common TCP/IP tool, this one allowing users to
   learn about the route that packets take from their local host to a
   remote host.  Although used often by network and system managers as a
   simple, yet powerful, debugging aid, traceroute can be used by end
   users to learn something about the structure of the Internet.

   The Traceroute command has the following general format (where "#"
   represents a positive integer value associated with the qualifier):

      TRACEROUTE [-m #] [-q #] [-w #] [-p #] {IP_address | host_name}



Kessler & Shepard                                               [Page 7]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


   where  -m   is the maximum allowable TTL value, measured as the
                number of hops allowed before the program terminates
               (default = 30)
          -q   is the number of UDP packets that will be sent with each
               time-to-live setting (default = 3)
          -w   is the amount of time, in seconds, to wait for an answer
               from a particular router before giving up (default = 5)
          -p   is the invalid port address at the remote host (default =
               33434)

   The Traceroute example below shows the route between a host at St.
   Michael's College in Colchester, Vermont (smcvax.smcvt.edu) and a
   host at Bellcore in Red Bank, New Jersey (thumper.bellcore.com).  The
   output has some interesting points:

   1. NEARnet, the New England Academic and Research Network, is a
      regional network serving the northeastern U.S.  The packets' route
      runs from St. Mike's NEARnet gateway (smc-gw) to the University of
      Vermont (uvm-gw), etc.  Note that some intermediate systems (see
      lines 4 and 16) do not have names associated with them.

   2. From NEARnet (lines 1-6), the packets travel on the National
      Science Foundation Network (NSFNET) T3 backbone (lines 7-11).  The
      NSFNET backbone nodes are identified as "ans.net" since the NSFNET
      is operated by Advanced Networks and Services, Inc. (ANS).  The
      packets travel within ANS' network on their core nodal switching
      subsystems ("cnss") until ready to jump off the backbone; line 11
      indicates an ANS exterior nodal switching subsystem ("enss").  The
      datagrams are then carried on the JvNCnet (lines 12-16), a regional
      network in New Jersey (note the use of SMDS!).  Finally, the
      datagrams are placed on Bellcore's internal network (lines 17 and
      18) for final delivery.

   3. Note that not all of the datagrams take the same route.  In
      particular, only two of the datagrams go through the ANS gateway
      referred to at line 10.  Note also line 17; here, the first two
      datagrams go through one router at Bellcore, while the third
      datagram goes through a companion router.

   TECHNICAL NOTE: Traceroute works by sending a sequence of User
   Datagram Protocol (UDP) datagrams to an invalid port address at the
   remote host.  Using the default settings, three datagrams are sent,
   each with a Time-To-Live (TTL) field value set to one.  The TTL value
   of 1 causes the datagram to "timeout" as soon as it hits the first
   router in the path; this router will then respond with an ICMP Time
   Exceeded Message (TEM) indicating that the datagram has expired.
   Another three UDP messages are now sent, each with the TTL value set
   to 2, which causes the second router to return ICMP TEMs.  This



Kessler & Shepard                                               [Page 8]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


   process continues until the packets actually reach the other
   destination.  Since these datagrams are trying to access an invalid
   port at the destination host, ICMP Destination Unreachable Messages
   are returned indicating an unreachable port; this event signals the
   Traceroute program that it is finished!  The Traceroute program
   displays the round-trip delay associated with each of the attempts.

   As an interesting aside, Traceroute did not begin life as a general-
   purpose utility, but as a quick-and-dirty debugging aid used to find
   a routing problem.  The code (complete with comments!) is available
   by anonymous FTP in the file "traceroute.tar.Z" from the host
   "ftp.ee.lbl.gov".  (See Section 2.5 for a discussion of anonymous
   FTP.)

   ==================================================================
** SMCVAX$ TRACEROUTE THUMPER.BELLCORE.COM
   traceroute to THUMPER.BELLCORE.COM (128.96.41.1), 30 hops max, 38
   byte packets
    1 smc-gw.near.net (192.80.64.5) 50 ms  20 ms  10 ms
    2 uvm-gw.near.net (131.192.152.1) 160 ms  50 ms  30 ms
    3 harvard-gw.near.net (131.192.65.1) 470 ms  60 ms  60 ms
    4 131.192.32.3 (131.192.32.3) 50 ms  50 ms  40 ms
    5 mit2-gw.near.net (131.192.7.1) 50 ms  40 ms  40 ms
    6 enss.near.net (192.54.222.6) 60 ms  90 ms  40 ms
    7 t3-2.Hartford-cnss49.t3.ans.net (140.222.49.3) 70 ms 100 ms  60 ms
    8 t3-3.Hartford-cnss48.t3.ans.net (140.222.48.4) 70 ms  40 ms  40 ms
    9 t3-2.New-York-cnss32.t3.ans.net (140.222.32.3) 50 ms  60 ms  70 ms
   10 * t3-0.New-York-cnss33.t3.ans.net (140.222.33.1) 340 ms  110 ms
   11 t3-0.enss137.t3.ans.net (140.222.137.1) 90 ms  420 ms  190 ms
   12 zaphod-gateway.jvnc.net (192.12.211.65) 70 ms  50 ms  70 ms
   13 airport1-gateway.jvnc.net (130.94.6.250) 390 ms  110 ms  60 ms
   14 airport4-gateway.jvnc.net (130.94.7.4) 70 ms  50 ms  60 ms
   15 coreSMDS-gateway.jvnc.net (130.94.7.106) 80 ms  130 ms  100 ms
   16 128.96.58.2 (128.96.58.2) 80 ms  70 ms  100 ms
   17 lab214b-cisco.cc.bellcore.com (128.96.34.40) 120 ms  120 ms
      lab214-cisco.cc.bellcore.com (128.96.34.101) 130 ms
   18 thumper.bellcore.com (128.96.41.1) 130 ms  430 ms  80 ms

   SMCVAX$
   ==================================================================











Kessler & Shepard                                               [Page 9]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


2.5. FTP

   The File Transfer Protocol (FTP) [16] is one of the most useful and
   powerful TCP/IP utilities for the general user.  FTP allows users to
   upload and download files between local and remote hosts.  Anonymous
   FTP, in particular, is commonly available at file archive sites to
   allow users to access files without having to pre-establish an
   account at the remote host.  The general form of the FTP command is:

        FTP [IP_address | host_name]

   As shown, FTP can be initiated in several ways.  In the example shown
   below, an FTP control connection is initiated to a host by supplying
   a host name with the FTP command; optionally, the host's IP address
   in dotted decimal form could be used.  If neither host name nor IP
   address are supplied in the command line, a connection to a host can
   be initiated by typing "OPEN host_name" or "OPEN IP_address" once the
   FTP application has been started.

   The remote host will now ask for a username and password.  If a
   legitimate, registered user of this host supplies a valid username
   and password, then the user will have access to any files and
   directories to which this username has privilege.  For anonymous FTP
   access, the username "anonymous" is used and the password (not shown
   in actual use) is "guest" (although an increasing number of systems
   ask that anonymous FTP users supply their Internet address as the
   password).

   The first command issued in the example below is "help ?", used to
   obtain a list of available FTP commands and help topics.  Although
   not always shown, nearly all TCP/IP applications have a help command.

   An example of the help for FTP's "type" command is shown in the
   sample dialogue.  This command is very important one, by the way; if
   transferring a binary or executable file, be sure to set the type to
   "image" (or "binary" on some systems).

   The "dir" command provides a directory listing of the files in the
   current directory at the remote host; the UNIX "ls" command may also
   usually be used.  Note that an FTP data transfer connection is
   established for the transfer of the directory information to the
   local host.  The output from the "dir" command will show a file
   listing that is consistent with the native operating system of the
   remote host.  Although the TCP/IP suite is often associated with
   UNIX, it can (and does) run with nearly all common operating systems.

   The directory information shown in the sample dialogue happens to be
   in UNIX format and includes the following information:



Kessler & Shepard                                              [Page 10]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


   o File attributes.  The first character identifies this as a
     directory (d), link (l), or individual file (-).  The next nine
     characters list the access permissions for three groups, namely,
     the owner, the owner's group, and all other users.  Three access
     privileges may be assigned to each file for each of these groups:
     read (r), write (w), execute (x), and/or search (s).

   o File owner and owner's group.

   o File size, in bytes.

   o Date of last modification.  If the date is followed by a timestamp,
     then the date is from the current year.

   o File name.

   After the directory information has been transferred, FTP closes the
   data transfer connection.

   The command "cd" is used to change to another directory, in this case
   the "Gov" directory (note that file and directory names may be case-
   sensitive).  As in DOS, "cd .." will change to the parent of the
   current directory.  The "CWD command successful" is the only
   indication that the user's "cd" command was correctly executed; the
   "show-directory" (may be truncated to fewer characters, as shown)
   command, if available, may be used to see which directory you are in.

   Another "dir" command is used to find all files ending with the
   characters ".act"; note the use of the "*" wildcard character.  We
   can now copy (download) the file of choice (The Fair Credit Reporting
   Act, 1992) by using the "get" (or "receive") command, which has the
   following general format:

      GET  remote_file_name  local_file_name

   FTP opens another data transfer connection for this file transfer
   purpose; note that the effective data transfer rate is 39.98 kbps.

   FTP's "put" (or "send") command allows uploading from the local host
   to the remote.  "Put" is often not available when using anonymous
   FTP.

   Finally, we terminate the FTP connection by using the "close"
   command.  The user can initiate another FTP connection using the
   "open" command or can leave FTP by issuing a "quit" command.  "Quit"
   can also be used to close a connection and terminate a session.





Kessler & Shepard                                              [Page 11]

RFC 1739           Primer on Internet & TCP/IP Tools       December 1994


   TECHNICAL NOTE: It is important to note that different FTP packages
   have different commands available and even those with similar names
   may act differently.  In the example shown here (using MultiNet for
   VMS), the "show" command will display the current directory; in
   another package (e.g., FTP Software's PC/TCP), "show" will display a
   file from the remote host at the local host.  Some packages have
   nothing equivalent to either of these commands!

      ==================================================================
   ** SMCVAX$ FTP FTP.SPIES.COM
      SMCVAX.SMCVT.EDU MultiNet FTP user process 3.2(106)
      Connection opened (Assuming 8-bit connections)
   ** Username: ANONYMOUS
   ** Password: GUEST

   ** WIRETAP.SPIES.COM> HELP ?
      Commands may be one of the following:
      ACCOUNT                       AGET
      APPEND                        APUT
      ASCII                         ATTACH