Librarian's note: I obtained the version of traceroute that comes with this package 
without any form of documentation. The following traceroute help file appears
to detail the options available in our program, but there are some discrepancies.
---------------------------------------------------------------------------------

                                                                traceroute(8)
                                                                  Unsupported

   Name
     traceroute - print the route that packets take to the network host

   Syntax
     /usr/etc/traceroute [ -m max_ttl ] [ -n ] [ -p port ] [ -q nqueries ] [
     -r ] [ -s src_addr ] [ -t tos ] [ -w ] [ -w waittime ] host [ packetsize ]

   Description
     The Internet is a large and complex aggregation of network hardware con-
     nected together by gateways.  Tracking the route one's packets follow
     (or finding the miscreant gateway that is discarding your packets) can
     be difficult.  The traceroute command uses the IP protocol `time to
     live' field and attempts to elicit an ICMP TIME_EXCEEDED response from
     each gateway along the path to a particular host.

     The only mandatory parameter is the destination host name or IP number.
     The default probe datagram length is 38 bytes, but this may be increased
     by specifying a packet size (in bytes) after the destination host name.

     This program attempts to trace the route an IP packet would follow to
     some internet host by launching UDP probe packets with a small ttl (time
     to live) then listening for an ICMP "time exceeded" reply from a gate-
     way.  We start our probes with a ttl of one and increase by one until we
     get an ICMP "port unreachable" (which means we got to "host") or hit a
     max (which defaults to 30 hops and can be changed with the -m flag).
     Three probes (which can be changed with the -q flag) are sent at each
     ttl setting and a line is printed showing the ttl, address of the gate-
     way and round trip time of each probe.  If the probe answers come from
     different gateways, the address of each responding system will be
     printed.  If there is no response within a 3 second timeout interval
     (which can be changed with the -w flag), a "*" is printed for that
     probe.

     We do not want the destination host to process the UDP probe packets so
     the destination port is set to an unlikely value.  The destination port
     value can be changed with the -p flag, if necessary.

   Options
     Additional traceroute options are:
        
     -m   Sets the max time-to-live (max number of hops) used in outgoing
          probe packets.  The default is 30 hops which is the same default
          used for TCP connections.

     -n   Prints hop addresses numerically rather than symbolically and
          numerically.  This saves a nameserver address-to-name lookup for
          each gateway found on the path.

     -p   Sets the base UDP port number used in probes (default is 33434).
          The traceroute command presumes that nothing is listening on UDP
          ports base to base+nhops-1 at the destination host (so an ICMP
          PORT_UNREACHABLE message will be returned to terminate the route
          tracing).  If another process islistening on a port in the default
          range, this option can be used to pick an unused port range.

     -r   Bypasses the normal routing tables and sends directly to a host on
          an attached network.  If the host is not on a directly-attached
          network, an error is returned.  This option can be used to ping a
          local host through an interface that has no route through it (for
          example, after the interface was dropped by routed(8c).

     -s   Uses the following IP address (which must be given as an IP number,
          not a hostname) as the source address in outgoing probe packets.
          On hosts with more than one IP address, this option can be used to
          force the source address to be something other than the IP address
          of the interface on which the probe packet is sent. If the IP
          address is not one of this machine's interface addresses, an error
          is returned and nothing is sent.

     -t   Sets the type-of-service in probe packets to the following value
          (default zero).  The value must be a decimal integer in the range 0
          to 255.  This option can be used to see if different types-of-
          service result in different paths.  (If you are not running 4.4BSD,
          this option is not relevant to you because services like telnet and
          ftp do not let you control the type-of-service .) Not all values of
          type-of-service are legal or meaningful - see the IP spec for
          definitions.  Useful values are probably `-t 16' (low delay) and
          `-t 8' (high throughput).

     -v   Verbose output.  Received ICMP packets other than TIME_EXCEEDED and
          UNREACHABLEs are listed.

     -w   Sets the time (in seconds) to wait for a response to a probe.  The
          default is 3 seconds.

   Examples
     The following command traces the route a packet takes from localhost to
     the host nis.nsf.net:

     localhost> traceroute nis.nsf.net

     traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
      1  helios.ee.lbl.gov (128.3.112.1)  19 ms  19 ms  0 ms
      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  39 ms
      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  39 ms  39 ms  39 ms
      6  128.32.197.4 (128.32.197.4)  40 ms  59 ms  59 ms
      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  59 ms
      8  129.140.70.13 (129.140.70.13)  99 ms  99 ms  80 ms
      9  129.140.71.6 (129.140.71.6)  139 ms  239 ms  319 ms
     10  129.140.81.7 (129.140.81.7)  220 ms  199 ms  199 ms
     11  nic.merit.edu (35.1.1.48)  239 ms  239 ms  239 ms

     Note that lines 2 and 3 are identical.  This is due to a bug in the ker-
     nel on the 2nd hop system - lbl-csam.arpa - that forwards packets with a
     zero ttl (a bug in the distributed version of 4.3BSD).  Note that you
     have to guess what path the packets are taking cross-country since the
     NSFNet (129.140) does not supply address-to-name translations for its
     NSSes.

     The following is another example of output from the traceroute command.
     Packets from localhost to the host allspice.lcs.mit.edu are being
     traced:

     localhost> traceroute allspice.lcs.mit.edu.
        
     traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  19 ms  19 ms
      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  19 ms
      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  19 ms  39 ms  39 ms
      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  20 ms  39 ms  39 ms
      6  128.32.197.4 (128.32.197.4)  59 ms  119 ms  39 ms
      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  39 ms
      8  129.140.70.13 (129.140.70.13)  80 ms  79 ms  99 ms
      9  129.140.71.6 (129.140.71.6)  139 ms  139 ms  159 ms
     10  129.140.81.7 (129.140.81.7)  199 ms  180 ms  300 ms
     11  129.140.72.17 (129.140.72.17)  300 ms  239 ms  239 ms
     12  * * *
     13  128.121.54.72 (128.121.54.72)  259 ms  499 ms  279 ms
     14  * * *
     15  * * *
     16  * * *
     17  * * *
     18  ALLSPICE.LCS.MIT.EDU (18.26.0.115)  339 ms  279 ms  279 ms

     Note that the gateways 12, 14, 15, 16 and 17 hops away either do not
     send ICMP "time exceeded" messages or send them with a ttl too small to
     reach localhost.  Gateways 14 through 17 are running the MIT C Gateway
     code that does not send "time exceeded" messages.  It is unclear what is
     happening with gateway 12.

     The silent gateway 12 in the above may be the result of a bug in the
     4.[23]BSD network code (and its derivatives):  4.x (x <= 3) sends an
     unreachable message using whatever ttl remains in the original datagram.
     Since, for gateways, the remaining ttl is zero, the ICMP "time exceeded"
     is guaranteed to not make it back to us.

     When this bug appears on the destination system it behaves as follows:

      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  39 ms
      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  39 ms  19 ms
      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  19 ms
      5  ccn-nerif35.Berkeley.EDU (128.32.168.35)  39 ms  39 ms  39 ms
      6  csgw.Berkeley.EDU (128.32.133.254)  39 ms  59 ms  39 ms
      7  * * *
      8  * * *
      9  * * *
     10  * * *
     11  * * *
     12  * * *
     13  rip.Berkeley.EDU (128.32.131.22)  59 ms !  39 ms !  39 ms !

     Note that there are 12 "gateways" (13 is the final destination) and the
     last half of them are "missing".  What is happening is that the host rip
     (a Sun-3 running Sun OS3.5) is using the ttl from our arriving datagram
     as the ttl in its ICMP reply.  The reply will time out on the return
     path (with no notice sent to anyone since ICMP's are not sent for
     ICMP's) until we probe with a ttl that is at least twice the path
     length.  This means that the host rip is really only 7 hops away.

     A reply that returns with a ttl of 1 is a clue this problem exists.  The
     traceroute prints a "!" after the time if the ttl is less than or equal
     to 1.  Since many systems continue to run obsolete or non-standard
     software, expect to see this problem frequently.

     Other possible annotations after the time are !H, !N, !P (got a host,
     network or protocol unreachable, respectively), !S or !F (source route
     failed or fragmentation needed - if either of these occurs, the associ-
     ated gateway is broken).  If almost all the probes result in some kind
     of unreachable, the traceroute command will give up and exit.

     This program is intended for use in network testing, measurement and
     management.  It should be used primarily for manual fault isolation.
     Because of the load it could impose on the network, you should not use
     traceroute during normal operations or from automated scripts.

   See Also
     netstat(1), ping(8)
